EP4163732A1 - Clock clutch mechanism - Google Patents

Abstract

The present invention relates to a clockwork clutch mechanism (100) in which flexible blades (52) of a clutch disc (5) are arranged to deform, so that- in the engaged position, the disc clutch (5) has a first diameter (D1), so that peripheral rigid clutch elements (51) come into contact with a surface (42) of a first wheel (4), the first wheel (4) driving, thanks to this contact, the clutch disc (5), the clutch disc (5) therefore driving a shaft (3), and the shaft (3) driving a second wheel (2), - in the disengaged position, the clutch disc (5) has a second diameter (D2) smaller than the first diameter (D1), so that the peripheral rigid clutch elements (51) no longer come into contact with the surface (42) of the first wheel (4).

Description

Technical area

The present invention relates to a clockwork clutch mechanism. The present invention also relates to a timepiece movement comprising such a mechanism, as well as a timepiece, for example a chronograph watch, in particular a wristwatch chronograph, comprising such a mechanism or such a movement. Although the mechanism according to the invention can be used to produce a clutch in a chronograph watch, it is not limited to such an application, but it can also be used for any other horological application which requires a clutch: for example and in a non-limiting way, it can be used in a striking clockwork mechanism.

State of the art

A chronograph watch is a timepiece that can be used to measure time. As a general rule, a chronograph watch comprises at least one indicator (such as a hand) which can be started and then stopped, by means of a pusher or another control member, in order to measure a duration. Then it can be returned to its starting point. In general, chronograph watches also include indicators for displaying the current time in addition to displaying the duration measured.

The usual chronograph watches take the energy necessary for the operation of the part of the movement allowing the measurement of a duration on the kinematic chain allowing to count and display the current time, that is to say on the kinematic chain linking an energy source, for example a barrel, to the regulating organ and to the watch wheels, which are linked to watch indicators to display the current hour, minute and/or second.

In order to take this energy necessary to set in motion the kinematic chain allowing the measurement of a temporal duration, it is necessary to produce a clutch between the kinematic chain which makes it possible to count and display the current time and that which makes it possible to measure a time span.

Two main members are used in the majority of operations of mechanisms for chronograph watches, namely control devices and clutch devices.

The control devices can be for example cam or column wheel. As they are known per se in the field of the art, they will not be described here.

The clutch devices make it possible to drive the kinematic chain of the chronograph by the kinematic chain making it possible to count and display the current time. In particular, the clutch devices make it possible to start and stop the chronograph kinematic chain very quickly, and also to block it by keeping the chronograph indicators stopped.

Various types of clutch devices, including vertical, horizontal, and swing gear clutch devices, are known.

Vertical clutch devices allow a so-called “vertical” clutch between the two kinematic chains, in particular between a wheel of one kinematic chain and a wheel of the other kinematic chain.

In the case of a vertical clutch, the energy transmission does not take place by toothing, but by friction, for example on the faces of the wheels. The advantage of this type of clutch is that the driving of the counter which allows the measurement of a time duration is done without starting jump. On the other hand, it is expensive because of the high number of parts and its development remains quite difficult. In addition, this vertical clutch requires a certain height in the movement. In addition, its operation involves high operating forces, which can cause operational problems.

Lateral or horizontal clutch devices make it possible to couple two wheels by bringing them into contact by their periphery, in particular by their teeth. The disadvantage of this type of clutch is that when driving the chronograph wheel it is possible to have a starting jump caused by a misalignment of the teeth of the two wheels. The gap is all the more reduced as there are teeth. However, gears with many teeth are difficult to manufacture and more subject to wear. In this type of device, there is no oscillating movement or tilting of the elements of these devices.

There are also oscillating pinion clutch devices, which allow transmission of energy from one wheel of one driveline to a wheel of the other driveline using an oscillating pinion. This oscillating pinion comprises a first toothing which is in permanent contact with the wheel of the kinematic chain which makes it possible to determine the current time. This oscillating pinion, under the action of an actuating device such as a rocker, oscillates or rocks, so that its second toothing comes into contact with the wheel which makes it possible to carry out a measurement of a duration , thus also putting it in rotation.

Similar to horizontal clutches, during an oscillating pinion clutch, the penetration of the teeth of the oscillating pinion into those of the chronograph wheel can cause a jump of the chronograph wheel and therefore of the chronograph indicator, leading to a delay in the information.

Other clutch solutions have been developed. An example of such a solution is described in the document EP2085832 . In the mechanism described in this document, when the user actuates a column wheel via a control push button in order to stop the chronograph, pliers press on a clutch disc thus blocking a chronograph wheel. Simultaneously, an isolator drives a rotating isolator wheel, which has the effect of radially displacing clutch elements using several tenons, thus stopping the chronograph mechanism. In this way, a clutch spring is no longer in contact with a drive plate, thus stopping the chronograph wheel. The described clutch comprises a radial spring and an axial or vertical conical spring, the latter being necessary for the correct operation of the reset.

When the user actuates the column wheel again via the control push button in order to start the chronograph, the clamps move away from the clutch disc, thus releasing the chronograph wheel. Simultaneously, the isolator drives the isolation wheel in rotation, which has the effect of radially displacing the clutch elements using the tenons. In this way, the clutch spring comes into contact with the drive plate, thus starting the chrono.

The clutch mechanism described is complex and comprises more than ten parts. In addition, the actuation of the clutch disc is indirect and is done via tenons. Finally, in order to achieve the coupling with the chronograph axis, several contacts take place between the different components (drive plate → clutch elements → spring → disc → friction spring → ring → axis), which leads to a significant loss of energy.

The document EP3671370 describes another clutch mechanism, in which, when a gripper is actuated in order to start the chronograph, its support element moves away from a clutch disc. At this time, elements pivot under the effect of springs. Positioned studs then abut against a chronograph wheel, which ensures the coupling and therefore the clutch.

When the clamp is actuated again in order to stop the chronograph, its support element comes into contact with the clutch disc, which causes certain elements of the clutch disc to pivot, thus disengaging the studs from the chronograph wheel and allowing the clutch to be released.

This clutch mechanism is complex, since it requires a clutch disc having elements arranged to pivot under the action of flexible blades and to accommodate tenons which are perpendicular to the plane of the disc. Since these studs perform the clutch with the chronograph wheel, the friction surface between the chronograph wheel and each of these studs is small, which reduces the reliability of the clutch. In addition, the mechanism described comprises several parts (clutch disc, several tenons, etc.), which does not facilitate the assembly of the mechanism, in addition to being complicated by the mounting of the tenons in the disc.

Brief summary of the invention

An object of the present invention is to provide a clutch mechanism free from the limitations of known clutch mechanisms.

Another object of the invention is to provide a clutch mechanism which comprises fewer components than the known clutch mechanisms.

Another object of the invention is to provide a clutch mechanism that is less bulky than the known clutch mechanisms.

Another object of the invention is to provide a clutch mechanism which is easier to mount than the known clutch mechanisms.

According to the invention, these objects are achieved in particular by means of the clutch mechanism according to claim 1.

• un arbre,
• une première roue (ou roue entraîneuse) arrangée pour être montée de manière librement rotative sur l'arbre et pour tourner en continu autour de l'arbre,
• une deuxième roue (ou roue entraînée) solidaire à l'arbre,
• un disque d'embrayage solidaire à l'arbre, et
• un dispositif de commande.

The clockwork clutch mechanism according to the invention comprises:

• a tree,
• a first wheel (or driving wheel) arranged to be freely rotatably mounted on the shaft and to rotate continuously around the shaft,
• a second wheel (or driven wheel) integral with the shaft,
• a clutch disc secured to the shaft, and
• a control device.

In this context, the expression "clutch disc (or second wheel) integral with the shaft" indicates that the disc (or the second wheel) and the shaft can be driven one by the other in a movement common, without necessarily being attached (e.g. directly attached) to each other. For example, a clutch disc frictionally bonded to the shaft is also integral with the shaft.

The clockwork clutch mechanism according to the invention is arranged to switch, under the action of the control device, from an engaged position to a disengaged position and vice versa. In particular, in the engaged position, the first wheel drives the second wheel (the drive not necessarily being direct), and in the disengaged position the first wheel no longer drives the second wheel.

• un moyeu central coopérant avec l'arbre,
• au moins deux éléments d'embrayage rigides périphériques, et
• au moins une lame flexible reliant chaque élément d'embrayage rigide périphérique au moyeu central.

According to the invention, the clutch disc belongs to a plane perpendicular to the shaft and in this plane it comprises:

• a central hub cooperating with the shaft,
• at least two peripheral rigid clutch elements, and
• at least one flexible blade connecting each peripheral rigid clutch element to the central hub.

In the context of the present application, the expression “flexible blade” designates a blade or a beam, arranged to deform elastically in the plane of the clutch disc, for example according to a bending movement.

In the context of the present application, the expression "rigid clutch elements" designates parts of the clutch disc which are not intended to be deformed during operation of the mechanism according to the invention, and whose rigidity is greater to that of flexible blades.

In the context of the present application, the expression “peripheral rigid clutch elements” denotes rigid clutch elements which are at the periphery of the clutch disc and in particular which define its outer diameter.

• en position embrayée, le disque d'embrayage ait un premier diamètre, en sorte que les éléments d'embrayage rigides périphériques entrent en contact avec une surface de la première roue, la première roue entraînant grâce à ce contact le disque d'embrayage, le disque d'embrayage entraînant donc l'arbre, et l'arbre entraînant la deuxième roue,
• en position débrayée, le disque d'embrayage ait un deuxième diamètre plus petit que le premier diamètre, en sorte que les éléments d'embrayage rigides périphériques n'entrent plus en contact avec la surface de la première roue.

According to the invention, the flexible blades are arranged to deform in the plane of the clutch disc, so that:

• in the engaged position, the clutch disc has a first diameter, such that the peripheral rigid clutch elements come into contact with a surface of the first wheel, the first wheel driving, thanks to this contact, the clutch disc, the clutch disc therefore driving the shaft, and the shaft driving the second wheel,
• in the disengaged position, the clutch disc has a second diameter smaller than the first diameter, so that the peripheral rigid clutch elements no longer come into contact with the surface of the first wheel.

In this context, the term "clutch disc diameter" refers to the largest dimension of the clutch disc.

Since the first wheel is arranged to be freely rotatably mounted on the shaft, its rotation in the disengaged position does not cause rotation of the shaft nor that of the second wheel. On the other hand, in the engaged position, the rotation of the first wheel allows the rotation of the shaft, and therefore of the second wheel which is integral with the shaft, via the clutch disc.

This solution has the particular advantage of comprising fewer components compared to known clutch mechanisms. Indeed, the clutch is produced by a single component, namely the clutch disc, without the need for tenons or a plurality of components which come into contact with each other to produce the clutch between the first wheel and the second wheel.

Consequently, the clutch mechanism according to the invention is less bulky than the known clutch mechanisms and can be used for example in timepieces having reduced thickness.

In addition, due to the reduced number of its components, the clutch mechanism is easier to mount than known clutch mechanisms.

Finally, in the clutch mechanism according to the invention, the transmission of energy takes place horizontally (or radially) not by toothing, but by friction. This type of mechanism will subsequently be called a horizontal (or radial) clutch mechanism by friction.

In one embodiment, the peripheral rigid clutch elements move, under the action of the flexible blades, with a movement which is a movement substantially of translation (or “quasi-translation”) in a radial direction of the clutch disc, between the engaged position and that disengaged. In other words, the clutch disc contracts (in the disengaged position) and expands (in the engaged position) under the action of the flexible blades.

The movement of the peripheral rigid clutch elements is a substantially translational movement because there is also a slight rotation of these elements around the central hub which is due to the deformation of the flexible blades. However, this rotation, of the order of magnitude of a few degrees, in particular less than 10°, is negligible with respect to the radial translation of the peripheral rigid clutch elements.

In one embodiment, the first wheel comprises a housing arranged to receive the clutch disc at least partially in the direction of the shaft.

In one embodiment, in the engaged position, each flexible blade is substantially straight. This makes it possible to reduce the low rotation of the clutch disc due to the deformation of the flexible blades, when passing from the engaged position to that disengaged and vice versa.

In one embodiment, the peripheral rigid clutch elements are in the shape of an arc of a circle and/or comprise a portion in the shape of an arc of a circle. In one embodiment, this circular arc has an angular opening comprised in the range between 20° and 170°, for example comprised in the range 30° to 120°. In one embodiment, the peripheral rigid clutch elements all have the same dimensions and/or the same shape. In another embodiment, they do not all necessarily have the same dimensions and/or the same shape.

In one embodiment, the clutch disc comprises a pair of parallel flexible blades connecting at least one element peripheral rigid clutch to the central hub. This makes it possible to further reduce the low rotation of the clutch disc due to the deformation of the flexible blades, when passing from the engaged position to that disengaged and vice versa. In other words, the fact of having two parallel blades makes it possible to come close to guiding in translation.

In one embodiment, the second wheel is a chorograph wheel and the central hub comprises central flexible blades, these central flexible blades being arranged to make it possible to adjust the value of the torque for which the shaft slips during a reset. zero.

In one embodiment, the central hub is arranged to limit the deformation of the central flexible blades.

• en position embrayée, le moyeu central ait un premier diamètre pour entrer en contact avec l'arbre,
• en position débrayée et lors de la remise à zéro de la roue de chorographe par un mécanisme de remise à zéro, le moyeu central ait un deuxième diamètre plus grand que le premier diamètre, de façon à ce que l'arbre puisse patiner sur le moyeu central.

Dans ce mode de réalisation donc, en position débrayée et lors de la remise à zéro, le disque d'embrayage a un diamètre externe plus petit que celui de la position embrayée, et le moyeu central a un diamètre plus grand que celui de la position embrayée. En d'autres mots, en position débrayée et lors de la remise à zéro, les éléments d'embrayage rigides périphériques se déplacent radialement vers le centre du disque, tandis que le moyeu central s'écarte de l'arbre. Cela permet également d'ajuster précisément le couple de friction pour la remise à zéro, dans le but d'obtenir un couple de friction très petit voire nul (absence de contact avec l'arbre si le moyeu central se détache complétement de l'arbre).In one embodiment, the second wheel is a chorographer wheel and the central hub is arranged so that,

• in the engaged position, the central hub has a first diameter to come into contact with the shaft,
• in the disengaged position and when the chorograph wheel is reset by a reset mechanism, the central hub has a second diameter larger than the first diameter, so that the shaft can slip on the hub central.

In this embodiment therefore, in the disengaged position and when resetting, the clutch disc has a smaller outer diameter than that of the engaged position, and the central hub has a larger diameter than that of the position engaged. In other words, in the disengaged position and during reset, the peripheral rigid clutch elements move radially towards the center of the disc, while the central hub moves away from the shaft. This also makes it possible to precisely adjust the friction torque for the reset, with the aim of obtaining a very small or even zero friction torque (no contact with the shaft if the central hub completely detaches from the shaft ).

In one embodiment, the central hub comprises at least two central rigid elements defining the first diameter in the engaged position, and the second diameter in the disengaged position. In other words, the central rigid elements approach in the engaged position, and move away in the disengaged position and when resetting the chorograph wheel.

• en position embrayée, la première surface est en contact avec la première roue, la deuxième surface étant éloignée d'une pince ;
• en position débrayée, la pince entre en contact avec la deuxième surface, ce qui éloigne la première surface de la première roue.

In one embodiment, at least one peripheral rigid clutch element comprises a first surface and a second surface adjacent to the first surface in the direction of the shaft, such that:

• in the engaged position, the first surface is in contact with the first wheel, the second surface being remote from a gripper;
• in the disengaged position, the clamp comes into contact with the second surface, which moves the first surface away from the first wheel.

• un corps rigide,
• deux mâchoires arrangées pour coopérer avec le disque d'embrayage,
• des lames flexibles reliant le corps rigide aux mâchoires.

Dans ce mode de réalisation, lors du passage de la position embrayée à celle débrayée, le corps rigide se déplace en translation dans une première direction dans un plan de la pince, en causant un déplacement en translation des mâchoires dans une deuxième direction dans ce plan, la deuxième direction étant sensiblement perpendiculaire à la première direction, les deux mâchoires se rapprochent (en position débrayée) respectivement s'éloignent (en position embrayée) lors de leur déplacement, ce qui permet notamment de pincer ou pas le disque d'embrayage.In one embodiment, the clamp includes:

• a rigid body,
• two jaws arranged to cooperate with the clutch disc,
• flexible blades connecting the rigid body to the jaws.

In this embodiment, when passing from the engaged position to the disengaged position, the rigid body moves in translation in a first direction in a plane of the gripper, causing a translational movement of the jaws in a second direction in this plane. , the second direction being substantially perpendicular to the first direction, the two jaws approach each other (in the disengaged position) respectively move apart (in the engaged position) during their movement, which makes it possible in particular to pinch or not the clutch disc.

In one embodiment, the gripper comprises a frame which does not move during passage from the engaged position to the disengaged position.

• une bascule arrangée pour coopérer avec le dispositif de commande,
• une première lame flexible reliant la bascule au bâti, et
• une deuxième lame flexible reliant la bascule au corps rigide.

In one embodiment, the clamp includes:

• a rocker arranged to cooperate with the control device,
• a first flexible blade connecting the rocker to the frame, and
• a second flexible blade connecting the rocker to the rigid body.

• au moins une lame flexible, et
• au moins un élément rigide en série de la lame flexible.

Dans ce mode de réalisation, cette lame flexible se déforme lors du passage de la position embrayée à celle débrayée et vice-versa, permettant le mouvement en translation des mâchoires. La combinaison de la lame flexible avec l'élément rigide permet de limiter voire annuler un mouvement parasite de rotation des mâchoires.In one embodiment, the frame is connected to each jaw via a mechanism for moving the jaws comprising:

• at least one flexible blade, and
• at least one rigid element in series with the flexible blade.

In this embodiment, this flexible blade is deformed when passing from the engaged position to the disengaged position and vice versa, allowing the translational movement of the jaws. The combination of the flexible blade with the rigid element makes it possible to limit or even cancel a parasitic movement of rotation of the jaws.

Although the clamp and its characteristics above can be combined with the clockwork clutch mechanism according to the invention, according to an independent aspect of the invention, this clamp can be combined with another clockwork clutch mechanism according to the invention , in particular with a clockwork clutch mechanism comprising a clutch disc different from that according to the invention and/or without a clutch disc.

In one embodiment, the present invention also relates to a timepiece movement comprising the timepiece clutch mechanism according to the invention.

In one embodiment, the present invention also relates to a timepiece, for example a chronograph watch, comprising the mechanism according to the invention or the timepiece movement according to the invention.

Brief description of figures

• La figure 1A illustre une vue en section d'un mécanisme d'embrayage selon un mode de réalisation de l'invention, en position embrayée.
• La figure 1B illustre une vue en section du mécanisme d'embrayage de la figure 1A, en position débrayée.
• La figure 2 illustre une vue en perspective d'un mécanisme d'embrayage selon un autre mode de réalisation de l'invention.
• La figure 3A illustre une vue par le haut d'un disque d'embrayage d'un mécanisme d'embrayage selon un mode de réalisation de l'invention, en position embrayée.
• La figure 3B illustre une vue par le haut du disque d'embrayage de la figure 3A, en position débrayée.
• La figure 4A illustre une vue par le haut d'un disque d'embrayage d'un mécanisme d'embrayage selon un autre mode de réalisation de l'invention, en position embrayée.
• La figure 4B illustre une vue en perspective du disque d'embrayage de la figure 4A.
• La figure 5A illustre une vue par le haut d'un disque d'embrayage d'un mécanisme d'embrayage selon un autre mode de réalisation de l'invention, en position embrayée.
• La figure 5B illustre une vue en perspective du disque d'embrayage de la figure 5A.
• La figure 6A illustre une vue par le haut d'un disque d'embrayage d'un mécanisme d'embrayage selon un autre mode de réalisation de l'invention, en position embrayée.
• La figure 6B illustre une vue en perspective du disque d'embrayage de la figure 6A.
• La figure 7 illustre une vue par le haut d'une pince d'un mécanisme d'embrayage selon un autre mode de réalisation de l'invention.
• La figure 8 illustre une vue en perspective de la pince de la figure 7, coopérant avec un dispositif de commande.
• La figure 9 illustre une vue par le haut d'une pince d'un mécanisme d'embrayage selon un autre mode de réalisation de l'invention.
• La figure 10 illustre une vue par le haut d'une pince d'un mécanisme d'embrayage selon un autre mode de réalisation de l'invention.
• La figure 11 illustre une vue par le haut d'une pince d'un mécanisme d'embrayage selon un autre mode de réalisation de l'invention.

Examples of implementation of the invention are indicated in the description illustrated by the appended figures in which:

• There Figure 1A illustrates a sectional view of a clutch mechanism according to one embodiment of the invention, in the engaged position.
• There figure 1B illustrates a sectional view of the clutch mechanism of the Figure 1A , in the disengaged position.
• There figure 2 illustrates a perspective view of a clutch mechanism according to another embodiment of the invention.
• There Figure 3A illustrates a top view of a clutch disc of a clutch mechanism according to one embodiment of the invention, in the engaged position.
• There Figure 3B shows a top view of the clutch disc of the Figure 3A , in the disengaged position.
• There figure 4A illustrates a top view of a clutch disc of a clutch mechanism according to another embodiment of the invention, in the engaged position.
• There figure 4B illustrates a perspective view of the clutch disc of the figure 4A .
• There figure 5A illustrates a top view of a clutch disc of a clutch mechanism according to another embodiment of the invention, in the engaged position.
• There figure 5B illustrates a perspective view of the clutch disc of the figure 5A .
• There Figure 6A illustrates a top view of a clutch disc of a clutch mechanism according to another embodiment of the invention, in the engaged position.
• There figure 6B illustrates a perspective view of the clutch disc of the Figure 6A .
• There figure 7 illustrates a top view of a clamp of a clutch mechanism according to another embodiment of the invention.
• There figure 8 illustrates a perspective view of the clamp of the figure 7 , cooperating with a control device.
• There figure 9 illustrates a top view of a clamp of a clutch mechanism according to another embodiment of the invention.
• There figure 10 illustrates a top view of a clamp of a clutch mechanism according to another embodiment of the invention.
• There figure 11 illustrates a top view of a clamp of a clutch mechanism according to another embodiment of the invention.

Example(s) of embodiment of the invention

In the following description provided by way of example, reference will be made, for simplicity, to a clutch mechanism for a chronograph watch. It should however be understood that the invention is not limited to such an application, but also includes any other horological application which requires a clutch. For example and in a way not limiting, the clutch mechanism according to the invention can be used in a striking watch mechanism.

There Figure 1A illustrates a cross-sectional view of a clutch mechanism 100 according to one embodiment of the invention, in the engaged position.

In the embodiment of the Figure 1A , a first wheel 4 (or clutch housing) is crimped on a ring 7 which is mounted in a freely rotatable manner on the axis 3 between a collar 8 and the ring 7. This first wheel 4 is provided with peripheral toothing 41 which is arranged so that the first wheel 4 can rotate continuously, for example by meshing with a barrel gear train (not shown).

The presence of the collar 8 and the ring 7 is not necessary, and any other element which can allow the first wheel 4 to be mounted in a freely rotatable manner on the shaft 3 can be used instead.

In the embodiment of the Figure 1A , a second wheel 2, which is for example a chronograph wheel, is mounted integral with the shaft 3, for example clamped to the shaft 3. In one embodiment, the second wheel 2 is driven by the shaft 3 in a common movement. Following the direction A of the shaft 3, relative to the clutch disc 5 the second wheel is mounted on the shaft 3 on the opposite side of the first wheel 4. The second wheel 2 is not in direct contact with the clutch disc 5 nor with the first wheel 4.

The 100 clutch mechanism shown in the Figure 1A also comprises a clamp 1, partially visible, which comprises two branches or jaws 10 controlled by a control device (not illustrated in the Figure 1A ), for example and without limitation a column wheel (as illustrated in the figure 2 ). The jaws 10 are arranged to come into direct contact with the clutch disc 5, in particular with an outer surface P of the peripheral rigid clutch elements 51.

In the embodiment of the Figure 1A , another collar 6 cooperates with the end of the shaft 3 opposite to that cooperating with the collar 8.

When the user actuates the control device, for example via a push button (or any other control device), the gripper 1 moves away from the clutch disc 5. The clutch disc, and in particular its surface F, then comes into contact with an (internal) cylindrical surface 42 of the first wheel 4, visible on the Figure 1A .

In this position, the clutch disc 5 has a first diameter so that its peripheral rigid clutch elements 51, and in particular their surface F, comes into contact with the surface 42 of the first wheel 4. The first wheel 4 drives through this contact the clutch disc 5, the clutch disc 5 therefore driving the shaft 3, and the shaft 3 driving the second wheel 2, by performing a radial friction clutch. The coupling of the shaft 3 and therefore of the second wheel 2 is then carried out.

In the embodiment of the Figure 1A , the first wheel 4 comprises a housing 40 arranged to receive at least partially in the direction A of the shaft 3 the clutch disc 5, so as to make contact between the peripheral rigid clutch elements 51 of the disc of clutch 5 and at least a portion of surface 42 axially delimiting this housing 40. In one embodiment, this housing is substantially cylindrical.

In the embodiment of the Figure 1A , clamp 1 acts on surface F of clutch disc 5 which is not received in this housing 40.

There figure 1B illustrates a sectional view of the clutch mechanism 100 of the Figure 1A , in the disengaged position. In this case, another pressure on a control member (not shown) acts on the control device (for example the column wheel 9 of the figure 2 ), and causes the clamp 1 to close. A space E is then created between the surface 42 of the first wheel 4 and the clutch disc 5.

The clutch disc 5 therefore contracts radially (ie in a plane perpendicular to the shaft 3) thereby blocking the axis 3 and the second wheel 2, which therefore stops. The first wheel 4 continues to spin freely on the shaft 3.

In one embodiment, the expansion of the clutch disc in the engaged position (visible in Figure 1A ) during the separation of the clamp 1 is made possible by a slightly pre-stressed assembly of the clutch disc 5 in the first wheel 4.

• en position embrayée (figure 1A), la première surface F est en contact avec la première roue 4, la deuxième surface P étant éloignée de la pince 1 ;
• en position débrayée (figure 1B), la pince 1 entre en contact avec la deuxième surface P, ce qui éloigne la première surface F de la première roue 4.

In the embodiment of figure 1A And 1B , at least one peripheral rigid clutch element 51 comprises a first surface F and a second surface P adjacent to the first surface F in the direction A of the shaft, so that:

• in the engaged position ( Figure 1A ), the first surface F is in contact with the first wheel 4, the second surface P being remote from the gripper 1;
• in disengaged position ( figure 1B ), the gripper 1 comes into contact with the second surface P, which moves the first surface F away from the first wheel 4.

The operation of the clutch mechanism according to the invention therefore relies on the contraction or expansion of the clutch disc 5.

There Figure 3A illustrates a top view of a clutch disc 5 of a clutch mechanism 100 according to one embodiment of the invention, in the engaged position, and the Figure 3B illustrates a view from above of the clutch disc 5 of the Figure 3A , in the disengaged position.

• un moyeu central 53 coopérant, notamment étant arrangé pour entrer en contact direct, avec l'arbre 3,
• au moins deux éléments d'embrayage rigides périphériques 51, et
• au moins une lame flexible 52 reliant chaque élément d'embrayage rigide périphérique 51 au moyeu central 53.

The clutch disc 5 according to the invention comprises:

• a cooperating central hub 53, in particular being arranged to come into direct contact with the shaft 3,
• at least two peripheral rigid clutch elements 51, and
• at least one flexible blade 52 connecting each peripheral rigid clutch element 51 to the central hub 53.

A flexible blade 52 can be parallelepipedal, or have another shape, so as to promote the desired mode of deformation and to block undesirable modes of deformation. Non-straight flexible strips 52, for example curved flexible strips, can also be imagined. The section of the flexible blades 52 is advantageously rectangular, but could also be different.

In the embodiment of figures 3A and 3B , the clutch disc 5 comprises three peripheral rigid clutch elements 51, this number being a good compromise between the length of the peripheral rigid clutch elements 51, which must be large enough to achieve good friction with the first wheel 4 , and at the same time which must be small enough to achieve efficient closing of the clutch disc 5 in the disengaged position.

In another embodiment, the number of peripheral rigid clutch elements 51 is 2N+1, N being an integer equal to or greater than 1.

In the embodiment of figures 3A and 3B , the peripheral rigid clutch elements 51 all have the same shape (in an arc of a circle) and the same dimensions. The section of the peripheral rigid clutch elements 51 is advantageously rectangular, but could also be different.

In another embodiment (not shown), the peripheral rigid clutch elements 51 do not all necessarily have the same shape or the same dimensions.

In the embodiment of figures 3A and 3B , each peripheral rigid clutch element 51 is connected to the central core 53 via a pair of flexible blades 52 parallel to each other. This makes it possible to further reduce the small rotation of the clutch disc 5 due to the deformation of the flexible blades 52, when passing from the engaged position to the disengaged position and vice versa. However, the presence of this pair of flexible blades 52 is not necessary, a single flexible blade 52 connecting each peripheral rigid clutch element 51 to the central hub 53 being sufficient for the operation of the clutch mechanism 100 according to the invention.

In the embodiment of figures 3A and 3B , the central hub 53 is substantially rigid. In another embodiment, the central hub 53 is constituted by flexible blades 52, or else also comprises flexible blades 52.

In the embodiment of figures 3A and 3B , the flexible blades 52 connect a free end of each peripheral rigid clutch element 51 to the central hub 53. In another embodiment (not shown), the flexible blades 52 connect another portion of each peripheral rigid clutch element 51 (for example a central portion) to the central hub 53.

Advantageously, the peripheral rigid clutch elements 51 define the outer diameter of the clutch disc 5. In the engaged position, visible on the Figure 3A , a first space E1 separates a peripheral rigid clutch element 51 from the adjacent one.

In the engaged position, visible on the Figure 3A , the clutch disc has a first diameter D1. In the disengaged position, visible on the Figure 3B , the flexible blades 52 deform under the action of the clamp 1 so that the clutch disc 5 has a second diameter D2 smaller than the first diameter D1. The maximum dimension D2 of the clutch disc in the disengaged position is therefore smaller than the maximum dimension D1 of the clutch disc in the engaged position. The clutch disc 5 in other words contracts, and the space E2 between a peripheral rigid clutch element 51 and the adjacent one decreases (E2<E1). In other words, the peripheral rigid clutch elements 51 come together in the disengaged position, during the contraction of the clutch disc 5.

In other words again, in the disengaged position, the clutch disc can register in a virtual disc smaller than that in which it can register in the engaged position.

In the embodiments of figures 3A and 3B , the peripheral rigid clutch elements 51 move, under the action of the flexible blades 52, with a movement which is substantially a movement of translation (or “quasi-translation”) in a radial direction of the clutch disc 5 , between the engaged position ( Figure 3A ) and the disengaged one ( Figure 3B ). In other words, the clutch disc 5 contracts (in the disengaged position) and expands (in the engaged position) under the action of the flexible blades 52.

The movement of the peripheral rigid clutch elements 51 is a substantially translational movement because there is also a slight rotation around the center C of the clutch disc 5 due to the deformation of the flexible blades 52. However, this rotation, of the order of magnitude of a few degrees, in particular less than 10°, is negligible with respect to the radial translation of the peripheral rigid clutch elements 51.

In one embodiment, in the engaged position, each flexible blade 52 is substantially straight or rectilinear, as for example visible on the Figure 3A .

There figure 4A illustrates a top view of a clutch disc 5 of a clutch mechanism 100 according to another embodiment of the invention, in the engaged position. There figure 4B illustrates a perspective view of the clutch disc 5 of the figure 4A .

The clutch disc 5 of the figures 4A and 4B comprises in total two first peripheral rigid clutch elements 51' and two second peripheral rigid clutch elements 51", the first and the second elements 51', 51" being arranged alternately.

In the embodiment of figures 4A and 4B , two internal rigid clutch elements 54 extend from the central hub 53. Each internal rigid clutch element 54 is also connected to both a first and a second peripheral rigid clutch element 51', 51" via a pair of parallel flexible blades 52, straight in the engaged position.

In the embodiment of figures 4A and 4B , these two pairs of parallel flexible blades 52 are arranged substantially perpendicular to each other.

In the embodiment of figures 4A and 4B , each pair of parallel flexible blades 52 is connected to the corresponding peripheral rigid clutch element 51 via an intermediate rigid clutch element 55 which is substantially perpendicular to the adjacent pair of parallel flexible blades 52. The advantage of the embodiment of the figures 4A and 4B resides in the fact that the actuation of the disc 5 can be carried out on any peripheral rigid clutch element 51 of the disc 5 and at least on a single element 51, since all the elements 51 are connected to each other. In this embodiment, a gripper 1 is not necessary to actuate the clutch, because this actuation can also be achieved for example by an arm with a single point of contact with a peripheral rigid clutch element 51. In d 'other words, in the embodiment of the figures 4A and 4B , the radial displacement of a single element 51 causes the displacement of all the other elements 51. In this case the clutch disc 5 has, on a macroscopic scale, a behavior similar to that of auxetic materials.

In the embodiment of figures 4A and 4B , each intermediate rigid clutch element 55 associated with a peripheral rigid clutch element 51" (on the left and on the right of the figures 4A and 4B ) is connected via a first flexible blade 56' to one end of an adjacent first peripheral rigid clutch element 51', and via a second flexible blade 56" to one end of a second peripheral rigid clutch element 51' adjacent.

There figure 5A illustrates a top view of a clutch disc 5 of a clutch mechanism 100 according to another embodiment of the invention, in the engaged position. There figure 5B illustrates a perspective view of the clutch disc 5 of the figure 5A .

In the embodiment of figures 5A and 5B , the central hub 53 comprises central flexible blades 530. In the illustrated embodiment, there are three of them and define a substantially triangular opening; it should however be understood that this embodiment is not limited to such a number nor to such a shape, provided that the shape created by the central flexible blades 530 is adapted to receive the shaft 3.

The mode of realization of figures 5A and 5B is particularly interesting in the case where the second wheel 2 is a chronograph wheel. In general, zeroing occurs when clamp 1 is closed on clutch disc 5.

In order to solve the torque problems during the reset, these central flexible blades 530 form a friction system in the center of the disc. The level of penetration on the diameter of the shaft 3 and/or the flexibility of the three central blades 530 make it possible to adjust precisely the value of the torque for which the shaft 3 slips during the reset.

In the embodiment of figures 5A and 5B , each central blade 530 is connected to at least one flexible blade 52 (or to a pair of parallel flexible blades in the illustrated embodiment) via an internal rigid clutch element 54 of the central hub 53. The flexible blade(s) 52 is (are) also connected to the rigid peripheral clutch element 51 corresponding.

In one embodiment, the central hub 53 is arranged so as to limit the deformation of the central blades 530, in particular when the clamp 1 is actuated. In other words, in this embodiment, the central hub 53 , and in particular the part of the central hub 53 which is close to the central blades 530, acts as an abutment for the central blades 530.

Although in the embodiment of figures 5A and 5B , the number of peripheral rigid clutch elements 51 is three, this number is not limiting and another number of peripheral rigid clutch elements 51 equal to or greater than two can be envisaged.

There Figure 6A illustrates a top view of a clutch disc 5 of a clutch mechanism 100 according to another embodiment of the invention, in the engaged position. There figure 6B illustrates a perspective view of the clutch disc 5 of the Figure 6A .

• en position embrayée (visible sur les figures 6A et 6B), le moyeu central 53 ait un premier diamètre pour entrer en contact avec l'arbre 3,
• en position débrayée et lors de la remise à zéro de la roue de chorographe par un mécanisme de remise à zéro (non illustrée), le moyeu central 53 ait un deuxième diamètre plus grand que le premier diamètre, de façon à soit réduire le couple de frottement et les forces de contact sur le moyeu central 53 (et par exemple permettre un patinage), soit à supprimer totalement le contact avec le moyeu central 53. On a donc deux fonctionnements différents possibles avec ce mécanisme.

In the embodiment of figures 6A and 6B , the second wheel (not shown) is a chorograph wheel and the central hub 53 is arranged so that,

• in the engaged position (visible on the figures 6A and 6B ), the central hub 53 has a first diameter to come into contact with the shaft 3,
• in the disengaged position and when the chorograph wheel is reset by a reset mechanism (not shown), the central hub 53 has a second diameter larger than the first diameter, so as to either reduce the friction torque and the contact forces on the central hub 53 (and for example allow slippage), or to completely eliminate contact with the central hub 53. There are therefore two different possible operations with this mechanism.

In this embodiment, in the disengaged position and when resetting, the clutch disc 5 has a smaller diameter than that of the engaged position, and the central hub 53 has a larger diameter than that of the engaged position. engaged. In other words, in the disengaged position and during reset, the peripheral rigid clutch elements 51 move radially towards the center C of the clutch disc 5 and therefore towards the shaft 3, while its hub central 53 deviates from the shaft 3. This also makes it possible to precisely adjust the friction torque for the reset.

To do this, the central hub 53 comprises at least two central rigid elements 531 defining the first diameter of the central hub 53 in the engaged position, and the second diameter in the disengaged position. In other words, the central rigid elements 531 come together in the engaged position (visible on the figures 6A and 6B ), and move away in the disengaged position and when resetting the chronograph wheel (not shown).

In the embodiment of figures 6A and 6B , the central hub 53 comprises central rigid elements 531. In the illustrated embodiment, there are three of them and define a substantially circular opening (they have a slightly curved shape), however this embodiment is not limited to such a number nor to such a shape, provided that the shape created by the central rigid elements 530 is adapted to receive the shaft 3.

In the embodiment of figures 6A and 6B , each central rigid element 531 is connected via an internal rigid clutch element 54 to two pairs of parallel flexible blades 52', 52": a first pair connects the internal rigid clutch element 54 to an adjacent internal rigid clutch element 54, and a second pair 52" connects the rigid clutch element internal 54 to a peripheral rigid clutch element 51.

Each pair of 52', 52" parallel blades figures 6A and 6B can be replaced by a single flexible blade.

Although in the embodiment of figures 6A and 6B , the number of peripheral rigid clutch elements 51 is three, this number is not limiting and another number of peripheral rigid clutch elements equal to or greater than two can be envisaged.

In one embodiment, the overall torque of the clutch disc 5, including the torque related to friction with the first wheel 4 and the torque related to the deformation of the flexible blades 52, is included in the range of 0.04 N mm at 0.09 N mm.

In one embodiment, it is possible to change the range of the friction torques, by modifying at least one of the following parameters: the thickness of the blades, the length of the blades, the material used for the blades, the shape of the blades, etc

There figure 7 illustrates a top view of a clamp 1 of a clutch mechanism 100 according to another embodiment of the invention.

• un corps rigide 13, qui dans l'exemple illustré est en forme de D, mais qui pourrait avoir une autre forme, par exemple et de façon non limitative une forme de C, de U ou de V,
• deux mâchoires 10 arrangées pour coopérer avec le disque d'embrayage 5 (non illustré) ; notamment, le disque d'embrayage 5 est arrangé pour être reçu dans le logement 15 défini par les mâchoires 10,
• des lames flexibles 16 reliant le corps rigide 13 aux mâchoires 10.

In the embodiment of the figure 7 , gripper 1 includes:

• a rigid body 13, which in the example illustrated is D-shaped, but which could have another shape, for example and without limitation a C, U or V shape,
• two jaws 10 arranged to cooperate with the clutch disc 5 (not shown); in particular, the clutch disc 5 is arranged to be received in the housing 15 defined by the jaws 10,
• flexible blades 16 connecting the rigid body 13 to the jaws 10.

When passing from the engaged position to the disengaged position, the rigid body 13 moves in translation in a first direction R in a plane of the gripper 1, causing a translational movement of the jaws in a second direction M1, M2 (M1 having a direction opposite to M2) in this plane, the second direction M1, M2 being substantially perpendicular to the first direction R, the two jaws 10 approaching (in the disengaged position) respectively moving away (in the engaged position) during their movement.

Clamp 1 may also include an outer frame 14 which does not move when changing from the engaged position to the disengaged position. In the embodiment of the figure 7 , the frame 14 has a U-shape and defines a space receiving the jaws 10 and the rigid body 13. In the embodiment of the figure 7 , the frame 14 comprises holes 140 of different sizes, which allow its fixing in a movement. However, the presence of these holes 140 is not necessary and any other means of fixing the clamp 1 to the movement can be used by those skilled in the art.

The two jaws 10 in the disengaged position therefore close concentrically on the clutch disc 5 (not shown). These jaws move in translation along a substantially rectilinear trajectory. In one embodiment, this movement is obtained by means of two mechanisms for moving the jaws 120 arranged between the frame 14 and the jaws 10.

• au moins une lame flexible 12,
• au moins un élément rigide 17 en série de la lame flexible 12.

Each jaw moving mechanism 120 comprises two elements in parallel, each element comprising:

• at least one flexible blade 12,
• at least one rigid element 17 in series with the flexible blade 12.

In the embodiment of the figure 7 , each mechanism for moving the jaws 120 comprises a rigid element 17 arranged between two flexible blades 12.

• une bascule 19 arrangée pour coopérer avec le dispositif de commande 9,
• une première lame flexible 18 reliant la bascule 19 au bâti 14, et
• une deuxième lame flexible 17 reliant la bascule 19 au corps rigide 13.

In one embodiment, the clamp 1 comprises:

• a rocker 19 arranged to cooperate with the control device 9,
• a first flexible blade 18 connecting rocker 19 to frame 14, and
• a second flexible blade 17 connecting rocker 19 to rigid body 13.

In general, the mechanism for moving the jaws 120, and in particular the flexible blade(s) 12, deform(s) when passing from the engaged position to the disengaged position and vice versa, allowing the guiding quasi-linear jaws 10.

Rocker 19 is pushed in correspondence of its head 190 by a control device, for example a column wheel 9, in the direction of arrow B of the figure 7 . The first flexible blade 18 makes it possible to produce a pivot and acts as a lever, allowing a change of direction at the other end of the rocker 9 (arrow C of the figure 7 ). The flexible blade 17 makes it possible to compensate for the effect of the rotation of the rocker 19.

The flexible blades 16 make it possible to obtain a reversal of trajectory, that is to say they make it possible to transform the movement of the rigid body 13 along the direction R into a movement of the jaws 10 along the direction M1, M2. The mechanisms for moving the jaws 120 allow a quasi-linear guiding of the jaws 10.

There figure 8 illustrates a perspective view of the gripper 1 of the figure 7 , cooperating with a control device, for example a column wheel 9.

In the example of the figure 8 , head 190 of rocker 19 is at the bottom of a column of column wheel 9. In this case, clamp 1 is therefore not controlled and is open (engaged position).

When the column wheel 9 rotates, the rocker 19 begins to pivot driving the rigid body 13 downwards (namely towards the rocker 19) with a translational movement in the direction R. The flexible blades 16, which on the figure 8 are oriented at 45° allow the jaws 10 to be moved via the two mechanisms 120 with parallel blades in the direction M1, M2.

Other non-limiting examples of pliers 1 are illustrated in the figures 9 to 11 .

There figure 9 illustrates a top view of a clamp 1 of a clutch mechanism 100 according to another embodiment of the invention. In this embodiment, clamp 1 comprises a first U-shaped rigid body 13′ connected to rocker 19 via flexible blade 17, and a second rigid body 13″ opposite first 13′ and C-shaped. The mechanisms for moving the jaws 120 in this case comprise two flexible blades, which are not necessarily parallel, one flexible blade connecting the first rigid body 13' to a jaw 10 and the other flexible blade connecting the second rigid body 13" to this jaw 10. In the embodiment of the figure 9 , the frame comprises part 13" and the two flexible blades 23 located on either side of part 13'.

There figure 10 illustrates a top view of a clamp 1 of a clutch mechanism 100 according to another embodiment of the invention. In this case too, the clamp 1 comprises a first rigid body 13′ in the shape of a U and connected to the rocker 19 via the flexible blade 17, and a second rigid body 13″ opposite the first 13′ and in the shape of a C. A flexible blade 16 connects each of the jaws 10 to the first rigid body 13', a pair of parallel flexible blades 120 connecting each of the jaws 10 to the second rigid body 13".

In the embodiment of the figure 10 , rocker 19' cooperates with first rigid body 13' via a second rocker 19".

There figure 11 illustrates a top view of a clamp 1 of a clutch mechanism 100 according to another embodiment of the invention. In this case the movement mechanism of the jaws 120 connecting each jaw 10 to the rigid body 13 comprises a specific arrangement of rigid bodies and flexible blades, allowing the transformation of the movement into translation of the rigid body 13 in a first direction in the plane of the clamp 1, in a translational movement of the jaws in a second direction in this plane, the second direction being substantially perpendicular to the first direction.
The flexible blades and/or the rigid bodies of the clutch disc 5 or of the clamp 1 belong to the same plane, which is that of a planar plate. The plate can be produced by photolithography from a wafer, for example a silicon wafer, by laser cutting, by LIGA, etc. In one embodiment, the clutch disc 5 or the clamp 1 is made of a composite material comprising a forest of juxtaposed nanotubes held by a matrix. In a variant, the nanotubes are carbon nanotubes. Alternatively, the matrix comprises amorphous carbon. In other variants, the nanotubes are made of other materials, for example boron nitride (“boron nitride nanotubes”, BNNT) or silicon. In a variant, the clutch disc 5 or the clamp 1 is made of steel. In another variant, the clutch disc 5 or the clamp 1 is made of glass, sapphire or alumina, of diamond, in particular of synthetic diamond (in particular synthetic diamond obtained by a process of chemical vapor deposition ), titanium, titanium alloy (in particular an alloy from the Gum metal (R) family) or an alloy from the Elinvar family, in particular Elinvar (R), Nivarox (R), Thermelast ( R), NI-Span-C (R) and Precision C (R), in shape memory alloy, in particular in Nitinol, in plastic or in any other material with a Young's modulus very little sensitive to variations in temperature.

Reference numbers used in the figures

1

Clamp

2

second wheel

3

TREE

4

first wheel

5

Clutch disc

6

Collar

7

Ring

8

Collar

9

Control device

10

Jaws

13, 13', 13"

Rigid body

14

Built

15

Accommodation

16

Flexible plier blade

17

Flexible blade linking the rocker to the rigid body

18

Flexible blade (pivot lever)

19, 19'

Seesaw

23

flexible blade

40

First wheel housing

41

Teeth

51, 51', 51"

Peripheral rigid clutch element

52, 52', 52"

flexible blade

53

central hub

54

Internal rigid clutch element

55

Intermediate rigid clutch element

56', 56"

flexible blade

100

Clockwork clutch mechanism

120

Jaw moving mechanism

140

holes

190

rocker head

530

Central flexible blade

531

Central rigid element

AT

shaft direction

VS

Clutch disc center

D1

First clutch disc diameter

D2

Second clutch disc diameter

E, E1, E2

Space

F

Contact surface with the clutch disc

M1, M2

Direction of movement of the jaws

P

Gripper contact surface

R

Direction of movement of the rigid part

Claims (15)

Clockwork clutch mechanism (100), comprising - a tree (3), - a first wheel (4) arranged to be freely rotatably mounted on the shaft (3) and to rotate continuously around the shaft (3), - a second wheel (2) secured to the shaft (3), - a clutch disc (4) integral with the shaft (3), - a control device (9), in which the mechanism (100) is arranged to pass, under the action of the control device (9), from an engaged position to a disengaged position and vice versa, in which the clutch disc (5) belongs to a plane perpendicular to the shaft (3) and in this plane it comprises - a central hub (53) cooperating with the shaft (3), - at least two peripheral rigid clutch elements (51), and - at least one flexible blade (52) connecting each peripheral rigid clutch element (51) to the central hub (53), and in which
the flexible blades (52) are arranged to deform in said plane, so that - in the engaged position, the clutch disc (5) has a first diameter (D1), so that the peripheral rigid clutch elements (51) come into contact with a surface (42) of the first wheel (4) , the first wheel (4) driving thanks to this contact the clutch disc (5), the clutch disc (5) therefore driving the shaft (3), and the shaft (3) driving the second wheel ( 2), - in the disengaged position, the clutch disc (5) has a second diameter (D2) smaller than the first diameter (D1), so that the peripheral rigid clutch elements (51) no longer come into contact with the surface (42) of the first wheel (4). The mechanism (100) according to claim 1, in which the peripheral rigid clutch elements (51) are arranged to move, under the action of the flexible blades (52), with a substantially translational movement in a radial direction of the clutch disc (5). The mechanism (100) according to one of claims 1 or 2, in which the first wheel (4) comprises a housing (40) arranged to receive at least partially in the direction (A) of the shaft (3) the disc clutch (5). The mechanism (100) according to one of claims 1 to 3, wherein in the engaged position, each flexible blade (42) is substantially straight. The mechanism (100) according to one of Claims 1 to 4, in which the peripheral rigid clutch elements (51) are in the shape of an arc of a circle and/or comprise a portion in the shape of an arc of a circle. The mechanism (100) according to one of Claims 1 to 5, in which at least one peripheral rigid clutch element (51) is connected to the central hub (53) by a pair of parallel flexible blades (52). The mechanism (100) according to one of claims 1 to 6, the second wheel (2) being a chronograph wheel, the central hub (53) comprising central flexible blades (530). The mechanism (100) according to claim 7, the central hub (53) being arranged to limit the deformation of the central flexible blades (530). The mechanism (100) according to one of claims 1 to 6, the second wheel (2) being a chronograph wheel, the central hub (53) being arranged so that, - in the engaged position, the central hub (53) has a first diameter to come into contact with the shaft (3), - in the disengaged position and when the chorograph wheel is reset by a reset mechanism, the central hub (3) has a second diameter larger than the first diameter, so that the shaft ( 3) can slip on the central hub (53). The mechanism according to claim 9, in which the central hub (3) comprises at least two central rigid elements (531) defining the first diameter in the engaged position, and the second diameter in the disengaged position and when the wheel is reset of chronograph. The mechanism (100) according to one of claims 1 to 10, wherein at least one peripheral rigid clutch element (51) comprises a first surface (F) and a second surface (P) adjacent to the first surface (F ) in the direction (A) of the shaft (3), so that: - in the engaged position, the first surface (F) is in contact with the first wheel (4), the second surface (P) being remote from a gripper (1); - in the disengaged position, the gripper (1) comes into contact with the second surface (P), which moves the first surface (F) away from the first wheel (4). The mechanism (100) according to claim 11, the clamp (1) comprising: - a rigid body (13), - two jaws (10) arranged to cooperate with the clutch disc (5), - flexible blades (12, 16) connecting the rigid body (13) to the jaws (10), in which, when passing from the engaged position to the disengaged position, the rigid body (13) moves in translation in a first direction R) in a plane of the gripper, by causing the jaws (10) to move in translation in a second direction (M1, M2) in said plane, the second direction (M1, M2) being substantially perpendicular to the first direction (R ), the two jaws (10) approaching respectively moving away during their movement. The mechanism (100) according to one of claims 11 or 12, the gripper (1) comprising a frame (14) which does not move during passage from the engaged position to that disengaged. The mechanism (100) according to one of claims 12 or 13, the clamp (1) comprising a rocker (19) arranged to cooperate with the control device, (9) and a first flexible blade (17) connecting the rocker ( 19) to the frame (14), and a second flexible blade (18) connecting the rocker (19) to the rigid body (13). The mechanism (100) according to one of claims 13 or 14, the frame (14) being connected to each jaw via a mechanism for moving the jaws (120) comprising: - at least one flexible blade (12), - At least one rigid element (17) in series with the flexible blade (12).

Images