EP1941326B1 - Detent escapement for a timepiece - Google Patents

Abstract

The escapement has an escape wheel (1) pivoted on an axis (X1), and a balance pivoted on an axis (X2). A detent (11) is pivoted on an axis (X3) and supports a pallet lock (21) interacting with a tooth of an escape wheel along a length of penetration to block the wheel in an idle phase over a course of which a balance exerts a free arc of oscillation. An impulse pallet (7) interacts with another tooth of the escape wheel, when the detent is pivoted for freeing the escape wheel. The teeth are placed on both sides of center lines (L) joining the axes (X1, X2) in the idle phase.

Description

Technical area

The present invention relates to a detent escapement for a timepiece, of the type comprising a toothed escape wheel and a rocker respectively pivoted on a first and a second axis. More specifically, the escapement according to the invention also comprises an expansion bearing a pallet of rest intended to cooperate with a first tooth of the escape wheel, along a certain length of penetration, to block it in a rest phase . In addition, the trigger is rotatably mounted on a third axis to be able to release the first tooth in a disengagement phase. A pulse pallet, integral with the balance by presenting a movement coaxial with oscillations of the balance, is intended to cooperate with a second tooth of the escape wheel to receive a pulse of the latter after the rest phase.

State of the art

Expansion exhausts of this type have already been described in the state of the art, as for example in the patent CH 3299 , issued March 5, 1891 to Emile James.

This document describes an exhaust structure comprising a detent having the shape of a rocker pivoted at one of its ends. This escapement comprises a pendulum bearing small and large trays on its axis, the small plate carrying a release pallet for rotating the trigger, while the large plate carries a notch performing the function of a pulse pallet, arranged so as to cooperate with the teeth of an escape wheel. The trigger comprises, moreover, a rest pallet intended to interact with the teeth of the escapement wheel to block the latter during periods of free oscillation of the balance.

To allow the pivoting of the trigger, it carries an elongated spring, which is secured to the trigger in the region of its end by which it pivots and whose free end is located on the trajectory of the pallet of clearance of the small plate. Thus, the latter acts on the spring, in a first direction of rotation of the balance, to rotate the trigger and allow the escape wheel to turn one step, while it simply crosses the spring by elastic deformation of the latter, in the other direction of rotation of the balance.

It emerges that one of the recognized main advantages of the detent escapement is that during operation, the impulse of the escapement wheel to the balance wheel is given only once per oscillation of this last, which results in a loss of energy due to the inertia of the exhaust wheel lower than in an escapement anchor.

However, the release operation of the trigger by interaction of the release pallet with the expansion spring and the inertia of the trigger in its pivoting are significant disturbing factors for the oscillating movement of the balance, d as important as the pendulum is small.

These disadvantages of the detent escapement, in particular, combined with the implementation of insecure mechanical connections making it particularly sensitive to shocks, have limited its distribution in modern watches, despite its obvious technical advantages.

Moreover, the patent US 180,290 , issued July 25, 1876 in the name of FH Voigt, describes a detent escapement in which the first and second teeth are adjacent and disposed on either side of the line of centers joining the first and second axes in the rest phase . This structure is advantageous because the fact of working rest and momentum on the teeth of the escapement wheel closest to the balance minimizes the impact of disturbances due to the release phase on the oscillations of the latter.

However, this exhaust does not include safety to prevent inadvertent release of the escape wheel in case of impact, which makes it particularly unsuitable from the point of view of possible implementation in a portable watch.

Disclosure of the invention

A main object of the present invention is to provide an alternative structure of exhaust escapement to obtain a high efficiency and increased impact safety against the known mechanisms of the prior art.

For this purpose, the invention relates to an expansion escapement of the type mentioned above, characterized in that it further comprises a limitation plate, coaxial and integral in rotation of the balance, having a periphery comprising a substantially circular main portion and a cutout arranged to be positioned opposite the pallet of rest in the disengagement phase. In addition, the main portion is dimensioned so as to define a safety distance, separating the pallet of rest from the main circular portion when positioned facing one another, less than the length of penetration of the pallet of rest on the first tooth of the escape wheel.

Thanks to these characteristics, the amplitude of the pivoting movements of the trigger is limited, in case of shock, directly by the interaction of the pallet of rest and the limiting plate, without it being necessary to provide additional elements. to ensure this function. Thus, the efficiency and the reliability of the escapement according to the present invention are sufficient to allow their implementation in timepieces of small dimensions, in particular because the escape wheel can not be released due to shock intervening outside the clearance phase.

In a preferred embodiment of the invention, the above purpose is achieved while limiting the size of the exhaust to allow its implementation in timepieces of small dimensions, such as wristwatches. Indeed, according to an advantageous characteristic, the line defined by the third axis of the trigger and the pallet rest is substantially perpendicular to the center line, which reduces the size of the exhaust significantly.

In a preferred embodiment variant, the escapement comprises a release pallet secured to the beam by being coaxial thereto, while the trigger carries a spring, a portion of which is disposed in the path of the release pallet.

In addition, it can be provided that the balance has a small and a large additional trays, both integral with the beam and centered on the second axis, the small plate carrying the release pallet while the large plate carries the pulse pallet.

Alternatively, it can be provided that the pulse pallet is carried directly by the limiting plate, the latter then also fulfilling the function of the large conventional tray.

In this case, it can be envisaged that the pulse pallet has a pulse surface located at a distance from the second axis less than or equal to the mean radius of the limiting plate and that the periphery of the latter also has a recess. next to the impulse surface to make it accessible. The cutout is then formed on the opposite side of the pulse pallet with reference to the recess, to allow the release of the pallet rest when the release pallet rotates the trigger.

In additional embodiments of the escapement according to the present invention, it also comprises an anti-gallop device, that is to say to limit the rotation of the escape wheel to a single pitch at each oscillation of the pendulum.

Brief description of the drawings

Other features and advantages of the present invention will appear more clearly on reading the detailed description of preferred embodiments which follows, made with reference to the accompanying drawings given as non-limiting examples and in which:

- the figure 1 represents a simplified perspective view of the detent escapement according to a first preferred embodiment of the present invention, a part of its constituent elements being torn off to make some others visible;

- the figure 2a represents a simplified top view of the visible detent escapement on the figure 1 in a first phase of its operation;

- the figure 2b represents a view similar to that of the figure 2a in a second phase of operation;

- the Figure 2c represents a view similar to that of the figure 2a in a third phase of operation;

- the figure 2d represents a view similar to that of the figure 2a in a fourth phase of operation;

- the figure 3 represents a simplified perspective view of a detail of the exhaust according to a further embodiment;

- the Figures 4a and 4b are simplified top views of a second construction detail of the escapement, respectively according to first and second preferred embodiments, and

- the figure 5 is a simplified perspective view of the detent escapement according to a further preferred embodiment of the present invention, some of its constituent elements being torn off to make some others visible.

Mode (s) of realization of the invention

The figure 1 is a simplified perspective view of the basic building elements of a detent escapement according to a preferred embodiment of the present invention. Some of these elements, normally hidden, have been made visible to expose the general principle of operation.

This escapement for a timepiece is intended to be integrated with a watch movement (not shown) comprising in particular a source of mechanical energy, such as a mainspring. Thus, the exhaust is connected to this energy source, via a gear train, by an escape wheel 1. The escape wheel 1 is of conventional type and is represented here with fifteen teeth 2, for illustrative non-limiting. It is intended to be mounted on the watch movement by a pivot 3 defining its axis of rotation X1.

The escapement also includes a rocker of which only the location of the pivot 4 is shown schematically for the sake of clarity. The balance is rotatably mounted relative to a second axis, referenced X2 on the figure 1 .

In the first preferred embodiment of the present invention, described in connection with the Figures 1 to 2d , a large plate 5 and a small plate 6 are integral with the shaft 4 of the beam by being coaxial. The small plate is visible in the figures thanks to the fact that a portion of the large plate has been omitted for the purposes of this presentation.

The large plate 5 carries a pulse pallet 7 whose end having the impulse surface is located at a distance from the axis X2 equal to the general radius of the large plate 5. Thus, the impulse surface is made accessible by cutting the large plate forming a recess 8 facing this surface.

The small plate 6 carries a release pallet 9, one end of which is arranged projecting with respect to the periphery of the small plate. The angular position of the clearance pallet is predefined with reference to the position of the impulse pallet on the large plate and the skilled person will not encounter any particular difficulty to adjust the relative positions of these two pallets.

Furthermore, the exhaust comprises an expansion 11 rotatably mounted with reference to a third axis, referenced X3 on the figure 1 . A spiral spring 12 is fixed by its outer end 13 to the watch movement, while its inner end (not visible) is integral with the trigger 11.

The trigger 11 comprises a rectilinear main arm 14 whose central region is mounted on a pivot 15 of axis X3. The main arm carries a cotter pin 16 at a first end 17, while its second end 18 is extended by a bend, itself followed by a short straight portion 19 extending in a direction substantially perpendicular to the direction of the arm main.

The spiral spring 12 acts on the main arm 14 of the trigger 11 to return the latter in a predefined angular orientation to the means of positioning a pin 20, integral with the watch movement and intended to cooperate with a flattened on the first end 17 of the trigger. It may be possible to connect the pin to the watch movement by means of an eccentric to allow an adjustable positioning, in a known manner.

On the one hand, the trigger 11 carries a pallet of rest 21 mounted in the region of the second end 18 of the main arm and intended to cooperate with the teeth 2 of the escape wheel, as it appears on the figure 1 .

On the other hand, the trigger also carries a stop 22 of substantially semi-cylindrical shape at the free end of the rectilinear portion 19, in other words, near the small plate 6.

An expansion spring 23, of generally rectilinear shape, is arranged on the trigger 11 so as to have a first end 24 housed in the slot of the cotter pin 16 and its second end 25 disposed in abutment against the flat portion of the stopper 22 It may be noted that the second end 25 has a small angle to the general direction of the spring 23 in a conventional manner.

It may be noted that the short rectilinear portion 19 comprises a finger 26 extending from the central portion of the portion 19, in a direction substantially tangential to the periphery of the small plate 6, and finished in a point. The function of this finger 26 will be explained below in connection with the detailed description of the operation of the exhaust which has just been described.

In general, the main stages of the kinematics of this escapement are conventional insofar as they include a rest phase, during which the escape wheel is blocked and the balance carries free oscillation arcs, a release phase during which the escape wheel is released to transmit a pulse to the beam, and a blockage of the escape wheel initiating a new rest phase during which the balance resumes its free oscillation.

These steps will now be explained below in relation to the detailed description of the Figures 2a to 2d .

The figure 2a is a top view of the exhaust shown on the figure 1 , the configuration and the relative positions of its different constituent elements being identical to those of the figure 1 .

As previously mentioned, the rest pallet 21 is arranged to cooperate with the teeth 2 of the escape wheel, more precisely with the tooth 200 at the moment represented on the figure 2a .

The escape wheel 1 undergoes a permanent force tending to turn it, clockwise, because of its kinematic connection with the energy source of the movement. The interaction of its tooth 200 with the rest pallet 21 ensures its locking in the position of the trigger shown on the figure 2a .

The pendulum completes a free oscillation arc in the direction indicated by the arrow F, at the instant shown, because the release pallet 9 carried by the small plate 6 comes into contact with the end 25 of the expansion spring. 23. At the same time, the pulse pallet 7, carried by the large plate 5, is positioned in the region of a tooth 201 adjacent to the tooth 200 but still located out of range of the pulse pallet.

It should be noted here that, if the line of centers L is defined as being the line passing through the first and second axes X1 and X2, the teeth 200 and 201 are located on either side of this line of centers L. Thus, these teeth are the two teeth of the escape wheel 1 closest to the axis X1 of rotation of the balance. As mentioned above, this particular feature contributes to reducing the impact of disturbances related to the inertia of the trigger on the pendulum oscillations.

Moreover, it appears on the figure 1 that, remarkably, the straight line passing through the axis X3 and the rest pallet 21 is substantially perpendicular to the line of centers L.

It may further be noted that the finger 26 of the trigger is disposed opposite a flat 28 of the periphery of the small plate 6, formed by a cutout thereof. Simultaneously, the rest pallet 21 is located opposite a cutout 29 formed in the periphery (partially represented in the form of a broken line) of the large plate 5 on the opposite side to that of the recess 8, with reference to the position of the impulse pallet 7.

The figure 2b represents the escape a brief moment after that of the figure 2a , when it is at the end of the release phase.

The rotation of the balance in the direction of the arrow F causes the appearance of a force exerted by the release pallet 9 on the end 25 of the spring 23, in the same direction. The presence of the stop 22 on the trigger 11 prevents the spring 23 from being deformed, which has the effect of transmitting the force exerted by the release pallet to the trigger 11 which pivots on its axis X3 during the disengagement phase.

At the end of this phase, the rest pallet 21 leaves the tooth 200 of the escape wheel to release the latter, the movement of the pallet rest being made possible, in the particular case shown, because of the presence of cutting 29 of the large tray. This feature will be explained in more detail in relation to the description of the figure 2d . Similarly, the finger 26 of the trigger follows the same movement as the rest pallet approaching the small plate 6, such a movement of the finger being possible due to the presence of the flat portion 28 of the small plate.

We see on the figure 2b whereas, while the pendulum has continued to rotate, the escape wheel 1 has not begun to rotate, which explains why Figures 2a and 2b the impulse pallet 7 has moved to pass the tooth 201 of the escape wheel and prepare the impulse phase.

The Figure 2c represents the device of the preceding figures at the beginning of the pulse phase.

The rest pallet has left the tooth 200 by releasing the escape wheel 1, the latter thus being driven in a rotational movement by the energy source of the watch movement, in the direction opposite to that indicated by the arrow F.

Meanwhile, the clearance pallet 9 has crossed the spring 23 by pivoting the trigger 11 and the beam starts a new arc free oscillation. The trigger 11 being simultaneously relieved of the force previously exerted by the release pallet, it is thus subject only to the restoring force of its spiral spring 12 which tends to bring its second end 18 towards the escape wheel 1. The rest pallet 21 then moves away from the large plate 5 while the finger 26 moves away from the small plate 6.

The simultaneous movements of the balance and the escape wheel 1 cause the positioning of the pulse pallet 7 on the trajectory of the tooth 201 which comes into contact with it, at the moment illustrated on the Figure 2c . A pulse is thus transmitted from the escape wheel to the balance to ensure the maintenance of oscillations of the latter.

After the impulse phase, the impulse pallet 7 leaves the trajectory of the tooth 201 by simultaneous rotation of the pendulum and the escape wheel, as shown in FIG. figure 2d . It can be noted that both the pulse pallet and the tooth 201 cross the line of centers L during the pulse phase.

The balance continues the ascending arc of free oscillation, while the rest pallet 21 is found positioned on the path of the tooth 201 due to the rotational movement of the trigger 11. The escape wheel 1 is therefore again blocked for a new rest phase, the tooth 201 replacing the tooth 200 in its prior stop function cooperating with the rest pallet of the trigger. At the same time, the tooth 202 has positioned near the large plateau, the side of the center line L opposite that of the tooth 201, waiting for the next pulse phase.

In this configuration, the rest pallet 21 is located at a distance from the axis X1 greater than the maximum radius of the large plate 5 while the finger 26 is located at a distance from the axis X1 greater than the maximum radius of the small plate 6 .

Thus, when the pendulum completes its upward arc and reverses the direction of rotation to perform the next downward arc, the rest pallet and the finger remains out of reach, respectively, the large and small trays.

During the downward arc of the balance, the clearance pallet 9 meets again the end 25 of the expansion spring 23 which, in this sense, can deform to disengage from the abutment 22 of the trigger and, thus allow the passage of the clearance pallet with a minimum of disturbance of the movement of the balance. The crossing of the spring by the release pallet is preferably optimized by the completion of a rounded at the edge of the pallet which lifts the spring during the downward arc. The spring 23 rests against the abutment 22 as soon as its end 25 is released by the release pallet 9.

The pendulum then ends its ascending arc before making a new downward arc to find itself in the situation represented on the figure 2a , with the difference that the escape wheel 1 has turned one step in the direction of clockwise rotation.

Now that the exhaust according to a first preferred embodiment has been described, it should be noted that a number of variants are possible without departing from the scope of the invention.

It will be noted in particular that the relative dimensions and positions of the trays and the escape wheel, as represented on the Figures 1 to 2d , respond to a search optimization of the congestion of the exhaust.

More specifically, the figure 2d illustrates that the average radius of the large tray 5 is preferably chosen such that the periphery of the tray defines a stop for the pallet rest 21 during the rest phases. The safety distance separating the pallet from the large platform is preferably less than the penetration length of the pallet rest on the tooth of the escape wheel. Thus, in the event of impact, if the trigger were to undergo a force tending to turn it clockwise, the pallet of rest would come into abutment against the large plate before having released the tooth of the escape wheel, this the latter thus playing the role of limitation plateau.

As an alternative or complement to what has been described above in relation to the safety distance, it is possible to provide another system such as that which has been described in relation to the Figures 1 to 2d that is to say the fact that the finger 26 cooperates with the periphery of the small plate 6. It is indeed possible to adjust the dimensions of the finger as well as its distance from the periphery of the small plate so that this distance is smaller than the penetration of the pallet of rest on the tooth of the escape wheel.

The skilled person will not encounter any particular difficulty to adapt the exhaust to his own needs by providing one of these protection devices against shocks or both. In the same way, he will be able to define the best compromise according to his needs as regards the safety distance separating the pallet of rest from the big plate.

It is of course understood from the above that the recess 8 and the cutout 29 of the large plate 5 are not absolutely necessary for the implementation of the present invention. As will be seen later, in connection with the description of the figure 5 other embodiments are possible to achieve the same level of efficiency of the exhaust according to the present invention.

Furthermore, the implementation of the present invention is also not limited to the use of a release pad associated with an expansion spring. By way of example, one could alternatively envisage a structure such as that described in the patent application EP 1 544 689 A1 already mentioned in the prior art. The device disclosed in this document should then be adapted to take account of the fact that the rest pallet and the part of the trigger which cooperates with the small plate are located on the same side of the trigger with reference to the axis of rotation X3 of the latter. Thus, the finger acting on the trigger should be disposed near the small plate, while the guide curve ensuring the return of the pallet rest towards the escape wheel should face the axis of rotation X1 of the pendulum, being arranged at a distance from the small plateau.

Alternative embodiments of the exhaust according to the present invention will now be exhibited in connection with the figures 3 , 4a and 4b .

The figure 3 is a perspective view showing an anti-gallop system complementary to the device described above to enhance the level of security of the latter. Only the essential elements to the understanding of this system have been represented on this figure.

The anti-gallop system according to this variant comprises a rocker 40 comprising a fork 41 and pivotally mounted on the watch movement, near the small plate 6. The pivoting amplitude of the rocker is limited by two stops 42, intended to cooperate with end 43 of the rocker farthest from the small plateau. The flip-flop 40 further comprises two inclined planes 44 arranged to cooperate with a jumper 45 to define two stable positions of the flip-flop corresponding to the stop positions. The fork 41 is arranged sufficiently close to the small plate to be able to interact with the clearance pallet 9.

Thus, with each passage of the release pallet in the fork, the pallet exerts pressure on the inner surface of the fork to tilt the lever 40 from one end position to the other.

Similarly to the operation of the fork in a Swiss anchor, the fork 41 defines two stops for the small plate in case of galloping, or rebate, to prevent the balance to make more than one turn around its axis X1 pivoting.

The skilled person will not encounter any particular difficulty in arranging the anti-gallop rocker in the region of the small plateau, according to his own needs and the space he will have on the turntable of his watch movement.

The Figures 4a and 4b represent particular embodiments of the spring for recalling the trigger in a predefined position, thus providing alternatives to the spiral spring 12 which has been previously described in connection with the main mode.

According to these two variants, the spring is formed of a piece with the trigger. Therefore, the latter is shown alone on the Figures 4a and 4b , the other constituents of the exhaust being in accordance with what has been explained above.

The figure 4a represents a first expansion variant 100 comprising a straight spring 101 extending in a rectilinear direction from the central region of the trigger, near its axis of rotation X3. For the implementation of this structure, it is necessary to provide a stop 102, integral with the watch movement and intended to prevent the rotation of the free end 103 of the spring in the disengagement phase to return the trigger to its position of rest, that is to say in the position it occupies during the rest phases of the escape wheel 1.

The figure 4b represents a second expansion variant 110 comprising a spring 111 of sinuous shape. The spring 111 has a first end 112 integral with the central region of the trigger 110, while its second end 113 is fixed on the watch movement by any suitable means, such as for example by a hole 114 made directly in its end 113 and, intended to cooperate with a screw or an eccentric to allow adjustment of the restoring force (not visible).

The realization of the return spring of the trigger according to these two variants reduces the number of parts needed while simplifying the mounting of the trigger in relation to this spring.

Of course, the two variants above are provided for illustrative purposes and the skilled person will not encounter any particular difficulty to adapt the shape of the spring to his own needs.

The figure 5 represents a simplified perspective view, similar to that of the figure 1 of the detent escapement according to a further preferred embodiment of the present invention. Part of the components of the exhaust is torn to make some others visible.

The elements already described in connection with the preceding figures bear the same numerical references for the sake of clarity.

The large plate 50 has a disk shape, of smaller radius than the large plate 5 of the first embodiment, and comprises a notch in which is housed the pulse pallet 7. Due to its reduced diameter, the large plate 50 does not fulfill the plateau function limitation but simply provides the support function for the pulse pallet, conventionally.

In return, a limiting plate 51, as such, is provided to fulfill this function in the present embodiment. It is mounted coaxial to small 6 and large trays 50, being integral with the pendulum. It has a periphery of which a main portion 52 is of circular shape, while a cutout 29 is formed in a predefined angular position with reference to the position of the impulse pallet 7, in a manner similar to that described in FIG. relationship with the first embodiment.

The mean radius of the limiting plate 51 is chosen such that the periphery of the latter is situated at a safety distance less than the penetration length of the pallet 21 on the teeth of the escape wheel 1 outside. of the clearance phase. In addition, as previously mentioned, the cutout 29 is positioned facing the pallet of rest during the disengagement phase to allow the pivoting of the trigger 11.

From the point of view of its operation, the exhaust of the figure 5 is similar to that of the figure 1 therefore, this point will not be repeated in detail.

Of course, those skilled in the art can modify the relative positions of the trays 6, 50 and 51 according to their own needs without departing from the scope of the present invention. In addition, all the variants described above can also be applied to this additional embodiment.

The foregoing description attempts to describe particular embodiments by way of non-limiting illustration and the invention is not limited, for example, to the particular form of the trigger or the different springs, or to the means to implement the release.

Claims (12)

1. Detent escapement for timepiece comprising
   a toothed escape wheel (1), pivoted on a first axis (X1),
   a balance, pivoted on a second axis (X2) and whereto an impulse pallet (7) is coaxial and secured,
   a detent (11, 100, 110) supporting a locking pallet (21) designed to cooperate with a first tooth (200) of said escape wheel, along a certain length of penetration, to block said first tooth in a locking phase,
   said detent being pivoted on a third axis (X3) to be capable of freeing said first tooth (200) in an unlocking phase,
   said impulse pallet (7) being designed to cooperate with a second tooth (201) of said escape wheel to receive an impulse from the latter after said unlocking phase,
   said first (200) and second (201) teeth being adjacent and arranged on either side of a center straight line (L) joining said first (X1) and second (X2) axes in said locking phase,
   characterized in that it also comprises a limiting plate (5, 51), coaxial and rotationally secured to said balance, having a periphery comprising a substantially circular main portion (52) as well as a cutout (29) arranged so as to be positioned across from said locking pallet in said unlocking phase, and
   in that said limiting plate (5, 51) is dimensioned so as to define a security distance, separating said locking pallet from said circular main portion when they are positioned facing each other, less than said length of penetration.
2. Escapement according to claim 1, characterized
   in that it comprises an additional small and large plate (50, 6), both integral with said balance and centered on said second axis (X2), said small plate (6) supporting a discharging pallet (9) while said large plate (50) supports said impulse pallet (7), said detent (11, 100, 110) supporting a spring (23) whereof one portion (25) is arranged on the path of said discharging pallet (9).
3. Escapement according to claim 2, characterized in that said limiting plate (51) has a diameter larger than the respective diameters of said small and large plates (50, 6).
4. Escapement according to claim 1, characterized in that it comprises a small plate (6), integral with said balance and centered on said second axis (X2), supporting a discharging pallet (9), said detent (11, 100, 110) supporting a spring (23) whereof one portion (25) is arranged on the path of said discharging pallet (9), and in that said impulse pallet (7) is supported by said limiting plate (5).
5. Escapement according to claim 4, characterized in that said impulse pallet (7) has an impulse surface located at a distance from said second axis (X2) smaller than or equal to the average radius of said limiting plate (5), and in that said periphery of said limiting plate (5) also has a recess (8) arranged across from said impulse surface, to make it accessible, said cutout (29) being arranged on the side opposite said impulse pallet (7) in reference to said recess.
6. Escapement according to any of claims 2 to 5, characterized in that said detent (11, 100, 110) comprises a main arm (14) mounted pivoting on said third axis (X3) through a central region and at a first end (17) of which is fixed said spring (23), while said locking pallet (21) is mounted on its second end (18), said main arm being extended by a bend, after its second end, itself extended by a short portion (19) supporting a banking (22) for said portion (25) of the spring (23) located on the path of said discharging pallet,
   said short portion (19) also supporting a finger (26) extending in a direction substantially tangential to the periphery of said small plate (6), the angle separating said finger from said small plate in reference to said third axis X3 being smaller than that corresponding to said length of penetration of said locking pallet (21) on said first tooth (200) of the escape wheel (1), and
   in that said small plate (6) has a truncated portion (28) on its periphery, arranged so as to be across from said finger when said discharging pallet (9) is arranged in contact with said spring (23).
7. Escapement according to any of the preceding claims, characterized in that said cutout (29) has, from a region of said main portion (52) of the periphery of the limiting plate (5, 51) distant from said impulse pallet (7), a first short portion having a curved contour followed by a ramp longer than said first portion, substantially rectilinear and extending in the direction of said impulse pallet (7) until it rejoins said main portion.
8. Escapement according to any of the preceding claims, characterized in that it comprises elastic means (12, 101, 111) arranged to exert a force on said detent (11, 100, 110) tending to engage said locking pallet (21) in the space separating two adjacent teeth from said escape wheel (1), said elastic means being formed in one piece with said detent.
9. Escapement according to claim 8, characterized in that said elastic means comprise a spring (111) having a winding shape whereof a first end (112) is integral with said detent (110) while its second end (113) has a predefined fixed position relative to said detent.
10. Escapement according to any of claims 2 to 9, characterized in that it also comprises an anti-tripping lever (40), able to pivot between two extreme stable positions along an axis parallel to said second axis, and having at least one contact surface arranged so as to cooperate with said discharging pallet (9) to cause said anti-tripping lever to pivot from one extreme position to the other.
11. Movement for timepiece comprising an escapement according to any of the preceding claims, an energy source and a gear train ensuring the kinematic connection between said energy source and the escape wheel of said escapement.
12. Timepiece comprising a movement according to claim 11.

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