EP3327518B1 - Timepiece comprising a switching device of a clockwork mechanism - Google Patents

Description

Field of the invention

The present invention relates to a device for switching a clock mechanism between two functional states.

In general, the present invention relates to a timepiece comprising a mechanism capable of switching between a first state and a second state, a switching device for this mechanism and an actuation device for this switching device. The switching device comprises a control member actuated by the actuating device and a switching member capable of switching on command from a first stable position, for which the mechanism is in its first state, to a second stable position, for which the mechanism is in its second state, and vice versa.

More particularly, the invention relates to a device for clutching a mechanism of a mechanical watch movement.

Invention background

Various clutch devices for a chronograph mechanism are known to those skilled in the art. The patent application EP 2 897 003 describes a conventional clutch device for a chronograph mechanism. This clutch device comprises an intermediate wheel which, when the clutch is engaged (device in the engaged state), engages simultaneously with a chronograph wheel and a driving wheel and which, when the clutch is released (device in the 'disengaged state), is removed from at least one of these two wheels to break the kinematic chain between them. To this end, the clutch device comprises a clutch lever which carries the intermediate wheel at the end of one of its two arms and which is associated with a first return spring so that the end of the second arm of this clutch lever remains in abutment against a column wheel. The column wheel thus forms a kind of cam and the aforementioned end of the clutch lever forms a cam follower. To activate this column wheel which alternately controls the clutch and the disengagement of the chronograph mechanism, a large rocker is provided which carries at one end a ratchet which is pivoted and associated with a second return spring.

The conventional clutch mechanism described above is complex. It comprises several pivoted members including a column wheel which is a complex part and therefore relatively expensive. The two aforementioned springs generate friction forces in the areas of mechanical contact provided, which cause wear. In addition, such springs are fragile and can have an elasticity which varies with age. Finally, the various organs must be precisely mounted in the timepiece to be functional, in particular the pawl for actuating the column wheel and the large rocker which generates the reciprocating movement of the pawl.

The document US 4,409,576 discloses an electrical switch formed by two magnets arranged in a housing with their respective magnetic axes combined. A first magnet is arranged movable along the direction of its magnetic axis and a second magnet is fixedly arranged in the housing and associated with a magnetic core made of a material having a certain magnetic permeability, this magnetic core being located between the two magnets. This document teaches that in a first position of the electrical switch where the movable magnet is located near the core, this movable magnet is attracted towards the core. On the other hand, in a second position of the electric switch where the magnet mobile is distant from the magnetic core, this moving magnet undergoes a force of repulsion from the assembly formed by the fixed magnet and the magnetic core. Thus, the first and second positions of the electrical switch are stable positions.

Summary of the invention

The object of the present invention is to propose a device for switching a timepiece mechanism of a different type from the aforementioned conventional device and which eliminates several drawbacks of such a conventional device.

• un premier aimant bipolaire qui est fixé à l'organe de commutation de manière à subir, lorsque cet organe de commutation passe de sa première position stable à sa deuxième position stable, un mouvement le long d'un chemin de commutation entre une première position de commutation et une deuxième position de commutation, et inversement,
• un deuxième aimant bipolaire qui est fixé au support du dispositif de commutation de manière à présenter continument une interaction magnétique avec le premier aimant bipolaire entre ses première et deuxième positions de commutation,
• au moins un premier élément à haute perméabilité magnétique formant au moins partiellement l'organe de commande.

To this end, the present invention relates to a timepiece comprising a mechanism which can switch between a first state and a second state, a device for switching this mechanism between its first and second states and a device for actuating this switching device. The switching device comprises a control member actuated by the actuating device and a switching member which can switch on command from a first stable position, for which the mechanism is in its first state, to a second stable position, for which the mechanism is in its second state, and vice versa. This timepiece includes:

• a first bipolar magnet which is fixed to the switching member so as to undergo, when this switching member moves from its first stable position to its second stable position, a movement along a switching path between a first switching and a second switching position, and vice versa,
• a second bipolar magnet which is fixed to the support of the switching device so as to continuously exhibit magnetic interaction with the first bipolar magnet between its first and second switching positions,
• at least a first element with high magnetic permeability at least partially forming the control member.

The control member is arranged so that, when repeatedly actuated by the actuator, the first element with high magnetic permeability undergoes a reciprocating movement (reciprocating movement) between a first position and a second control position. The switching device is arranged so that, when the first element with high magnetic permeability is in its first control position, the first and second magnets generate between them a magnetic repulsive force over substantially the whole of the switching path and so that when the first element with high magnetic permeability is in its second control position, the first and second magnets generate between them a magnetic attraction force on at least part of the switching path, this part being located on the side of the second bipolar magnet.

In a specific embodiment, which will not be described below, a spring of relatively low return force is provided in addition to the magnetic switching device to participate in the movement of the switching member in one direction and / or to help maintaining this switching member in one of its stable positions. In particular, when the switching path is relatively long, such a spring can act on the switching member for, when the first element with high magnetic permeability is in its second control position, move this switching member on a first part of the switching path located on the side opposite to the second bipolar magnet, until the magnetic attraction force intervenes to attract the switching member towards the second bipolar magnet.

In a preferred embodiment, the magnetic repelling force has a sufficient intensity and range so that it can actuate the switching member alone between its first stable position and its second stable position and then maintain it in this second stable position; while the magnetic force of attraction has an intensity and a range which are sufficient for it to be able to actuate alone the switching member between its second stable position and its first stable position and then to maintain it in this first stable position.

Thanks to the magnetic system of the invention and in particular to the control member which comprises at least one element with high magnetic permeability movable between two above-mentioned control positions, the magnetic switching device defines a bistable system. In addition, in the preferred embodiment, mentioned above, this device switching requires no return spring associated with the switching member.

In a preferred embodiment, the control member is formed by a rocker pivoted so that the element with high magnetic permeability undergoes a rotational movement between two determined angular positions when this control rocker is actuated. Such a rocker constitutes a simpler part to produce than a column wheel. In particular, the control lever is pivoted so that the first element with high magnetic permeability is rotated between a first angular position and a second angular position defining the first control position and the second control position respectively. Then, when the first element with high magnetic permeability is in its second angular position, this first element is substantially located on an alignment axis defined by the magnetic axis of the second bipolar magnet so that it is substantially between the first and second bipolar magnets. On the other hand, in its first angular position, the first element with high magnetic permeability is spaced from the abovementioned alignment axis.

It will be noted that the actuation of the control lever does not require a pivoted pawl and associated with a return spring. It will also be noted that the magnetic system makes it possible to avoid any contact between the control member and the switching member.

In an advantageous variant, the switching path of the first bipolar magnet is substantially coincident with the alignment axis defined by the magnetic axis of the second bipolar magnet and this first bipolar magnet is arranged with its magnetic axis substantially oriented along this axis d alignment, the first and second bipolar magnets being arranged with their opposite polarities.

Brief description of the drawings

• La Figure 1 montre schématiquement un système magnétique dont le fonctionnement particulier est mis à profit dans la présente invention;
• La Figure 2 représente un graphe de la force magnétique subie par un aimant mobile du système magnétique de la Figure 1 en fonction de sa distance d'éloignement d'un élément à haute perméabilité magnétique formant une partie de ce système magnétique;
• Les Figures 3 et 4 sont des vues en plan d'un mode de réalisation de l'invention dans lequel un mécanisme chronographe est commuté par un dispositif d'embrayage entre un état embrayé et un état débrayé;
• Les Figures 5A à 5D représentent diverses phases successives d'un actionnement d'une bascule de commande entre ses deux positions angulaires de commande;
• Les Figures 6A à 6D représentent schématiquement le système magnétique de l'invention dans quatre situations particulières avec les forces magnétiques respectives qui sont exercées sur un aimant porté par une bascule d'embrayage; et
• La Figure 7 donnent quatre courbes de couple en fonction de la position angulaire de la bascule de commande, ces courbes montrant les couples subis respectivement par cette bascule de commande et la bascule d'embrayage lorsque cette dernière est soit dans sa position embrayée, soit dans sa position débrayée.

The invention will be described below in detail with the aid of appended drawings, given by way of non-limiting examples, in which:

• The Figure 1 schematically shows a magnetic system whose particular operation is exploited in the present invention;
• The Figure 2 represents a graph of the magnetic force undergone by a mobile magnet of the magnetic system of the Figure 1 depending on its distance from an element with high magnetic permeability forming part of this magnetic system;
• The Figures 3 and 4 are plan views of an embodiment of the invention in which a chronograph mechanism is switched by a clutch device between a engaged state and a disengaged state;
• The Figures 5A to 5D represent various successive phases of an actuation of a control lever between its two angular control positions;
• The Figures 6A to 6D schematically represent the magnetic system of the invention in four particular situations with the respective magnetic forces which are exerted on a magnet carried by a clutch lever; and
• The Figure 7 give four torque curves as a function of the angular position of the control lever, these curves showing the torques undergone respectively by this control lever and the clutch lever when the latter is either in its engaged position or in its disengaged position .

Detailed description of the invention

We will begin by describing using Figures 1 and 2 a magnetic system which ingeniously takes advantage of the present invention to realize a bistable switching device, without contact between the control member and the switching member and without requiring a return spring to bring and then maintain this switching member in either of its two stable positions .

The magnetic system 2 comprises a first fixed magnet 4, an element with high magnetic permeability 6 and a second magnet 8 which is movable, along an axis of displacement coincident here with the alignment axis 10 of these three magnetic elements, relative to the assembly formed by the first magnet 4 and the element 6. This element 6 is arranged between the first magnet and the second magnet, close to the first magnet and in a determined position relative to the latter. In a particular variant, the distance between the element 6 and the magnet 4 is less than or substantially equal to one tenth of the length of this magnet along its axis of magnetization. Element 6 consists for example of carbon steel, tungsten carbide, nickel, FeSi or FeNi, or other alloys with cobalt such as Vacozet ® (CoFeNi) or Vacoflux ® (CoFe). In an advantageous variant, this element with high magnetic permeability consists of a metallic glass based on iron or cobalt. Element 6 is characterized by a saturation field Bs and a permeability µ. The magnets 4 and 8 are for example made of ferrite, FeCo or PtCo, rare earths such as NdFeB or SmCo. These magnets are characterized by their remanent field Br1 and Br2.

The element with high magnetic permeability 6 has a central axis which is preferably substantially coincident with the magnetization axis of the first magnet 4 and also with the magnetization axis of the second magnet 8, this central axis being here confused with the alignment axis 10. The respective magnetization directions of the magnets 4 and 8 are opposite. These first and second magnets therefore have opposite polarities and they are liable to undergo relative movement between them over a certain relative distance. The distance D between the element 6 and the movable magnet 8 is indicated to Figures 1 and 2 . Note that the axis 10 is provided here linear, but this is a non-limiting variant. The axis of movement can also be curved, as in the embodiment which will be described later. In the latter case, the central axis of the element 6 is preferably approximately tangent to the axis of curved displacement and thus the behavior of such a magnetic system is, at first approximation, similar to that of the magnetic system described here. . This is all the more true as the radius of curvature is large relative to the maximum possible distance between the element 6 and the movable magnet 8. In a preferred variant, as shown in FIG. Figure 1 , the element 6 has dimensions in a plane orthogonal to the central axis 10 which are greater than those of the first magnet 4 and those of the second magnet 8 in projection in this orthogonal plane. It will be noted that, in the case where the second movable magnet abuts at the end of the race against the element with high magnetic permeability, this second magnet advantageously comprises a hardened surface or a thin layer of hard material on its surface.

The two magnets 4 and 8 are arranged in magnetic repulsion so that, in the absence of the element with high magnetic permeability 6, a magnetic repulsion force tends to separate these two magnets from one another. However, surprisingly, the arrangement between these two magnets of the element 6 reverses the direction of the magnetic force exerted on the movable magnet when the distance between this movable magnet and the element 6 is sufficiently small, so that the mobile magnet then undergoes a magnetic attraction force. Curve 12 of the Figure 2 represents the magnetic force exerted on the movable magnet 8 by the magnetic system 2 as a function of the distance D between the movable magnet and the element with high magnetic permeability 6. It is noted that the movable magnet undergoes, over a first range D1 of the distance D, overall a magnetic attraction force which tends to hold the magnet 8 against the element 6 or to bring it towards it in the event of separation, this overall attraction force resulting from the presence of the element with high magnetic permeability (in particular ferromagnetic) which allows an inversion of the magnetic force between two magnets arranged in magnetic repulsion. Then, the element 6 and the two magnets are arranged so that the second magnet 8 undergoes, over a second range D2 of the distance D, overall a magnetic repulsion force. This second range corresponds to distances between the element 6 and the magnet 8 which are greater than the distances corresponding to the first range of the distance D. The second range is limited by a maximum distance D _max which is generally defined by a stop limiting the distance of the movable magnet.

The magnetic force exerted on the movable magnet is a continuous function of the distance D and it therefore has a zero value at the distance Dinv for which there is inversion of this magnetic force. This is a remarkable operation of the magnetic system 2 which is implemented in the switching device according to the invention. The inversion distance D _inv is determined by the geometry of the three magnetic parts forming the magnetic system and by their magnetic properties. This inversion distance can therefore be selected, to a certain extent, by the physical parameters of the three magnetic elements of the magnetic system 2 and by the distance separating the fixed magnet from the ferromagnetic element. The same goes for the evolution of the slope of the curve 12, the variation of this slope and in particular the intensity of the attraction force when the movable magnet approaches the ferromagnetic element which can thus be adjusted. .

With reference to Figures 3 to 7 , an embodiment of the invention will be described below.

The watch movement 22 includes a chronograph mechanism 24 partially represented by the chronograph wheel 26. Conventionally, this chronograph mechanism can switch between a first disengaged state, that is to say at rest, and a second state clutch in which the chronograph wheel 26 is kinematically coupled to the wheel coach 28 of the watch movement. To this end, a switching device for the chronograph mechanism is provided, forming a clutch device 30 for this mechanism, and an actuation device 32 for this clutch device. The clutch device 30 comprises a control member, formed by a control lever 34 actuated by the actuator, and a switching member 36 which comprises a clutch lever 38 mounted on a plate 23, a bridge rocker 40 and a clutch wheel 42 pivoted between this rocker and this bridge. The switching member 36 can be placed on command from a first stable position ( Figure 3 ), in which an arm of the rocker 38 is in abutment against the stop 44 and the clutch wheel in a position not engaged with the chronograph wheel, in a second stable position ( Figure 4 ), in which the aforementioned arm of the lever 38 is in abutment against the stop 45 and the clutch wheel in a position meshed with the chronograph wheel; and vice versa.

To this end, a first bipolar magnet 50 is fixed to a first end of the lever 38 which is pivoted about an axis 46 at its second end. When this switching member passes from its first stable position to its second stable position, the magnet 50 undergoes a movement along a switching path defined by the arc of circle traversed by this magnet between its first switching position and its second switching position, corresponding respectively to the first and second stable positions of the switching member. The magnet 50 follows the same path in the opposite direction when it passes from its second switching position and its first switching position.

Next, the timepiece 22 comprises a second bipolar magnet 52 which is fixed to the plate 23 so as to continuously exhibit a magnetic interaction with the first bipolar magnet 50 between its first and second switching positions.

According to the invention, the control lever 34 comprises a first element with high magnetic permeability 54 and it is arranged so that, when it is actuated repeatedly by the actuating device, the first element with high magnetic permeability undergoes a back and forth movement between a first control position and a second control position. The control rocker is pivoted so that the first element 54 is rotated between a first angular position ( Figure 3 ) and a second angular position ( Figure 4 ) respectively defining the first control position and the second control position. When the first element 54 is in its second angular position, it is located substantially between the first and second bipolar magnets, so as to form with these two bipolar magnets a magnetic system of the type described above in Figures 1 and 2 .

Preferably, in its second angular position, the first element 54 is located on an alignment axis 56 defined by the magnetic axis of the magnet 52 so that it is located substantially between the first and second bipolar magnets; whereas, in its first angular position, the first element 54 is spaced from the alignment axis 56. Preferably, as is the case in the embodiment described, the switching path of the bipolar magnet 50 is substantially coincident with the alignment axis 56, so that the two bipolar magnets are substantially aligned along this alignment axis for any position of the magnet 50 along the switching path. Then, the magnet 50 is arranged with its magnetic axis substantially oriented along the alignment axis and so that the first and second bipolar magnets 50 and 52 have their opposite polarities.

In the advantageous variant described using the Figures, see in particular the Figures 4 and 5D , it will be noted that when, on the one hand, the control lever 34 is in its second control position and the first element 54 is then located opposite the second magnet 52 and, on the other hand, the switching member 36 is in its second stable position in which the first magnet 50 undergoes a magnetic attraction force, this first magnet, the second magnet 52 and the high permeability element 54 are all aligned on the alignment axis 56, that is to say that the respective magnetic axes of these two magnets and the longitudinal axis of the element 54 are parallel and located on the same line. The fact that the alignment axis intercepts the axis of rotation 58 represents an advantageous case, but not at all necessary.

The control lever 34 further comprises a second element with high magnetic permeability 60 arranged so as to be substantially aligned with the first and second bipolar magnets 50 and 52 when the first element with high magnetic permeability 54 is in its first control position ( Figure 3 ). It will be noted at the outset that this second element 60 is not essential to the invention. Thus, in a particular variant, the control lever comprises only a single element with high magnetic permeability, namely element 54. However, the second element 60 is advantageous because it serves in particular to partially channel the flux of the second magnet 52 along the alignment axis 56 when the control lever is in its first control position and thus favor its interaction with the first magnet 50 without the element 54 deviating too much the magnetic fluxes of the magnets in its transverse direction relative to the alignment axis. In addition, this element 60 serves to adjust the magnetic repulsion force and in particular to limit this force. In an advantageous variant, the second element with high magnetic permeability is arranged so as to be located closer to one or the other of the first and second bipolar magnets regardless of the position of the first bipolar magnet along the switching path , so as to have a magnetic repulsion force on the whole of this switching path.

The control lever comprises a positioning device 62 formed by a pin 66 associated with a positioning spring 64. This spring has two positioning recesses which respectively define the first and second angular positions of the lever when the pin is successively housed in these two hollows. The control lever further comprises an opening 68, between its pivot axis 58 and the first element with high magnetic permeability 54, in which the second magnet 52 is arranged, this opening having a contour provided so that the control lever can freely rotate between its first and second angular positions. In the variant shown, the opening 68 has the form of an annular sector and the elements 54 and 60 are located opposite this opening relative to the pivot axis, on either side of an axis of symmetry of the annular opening.

The actuating device 32 comprises a shuttle 72 guided in translation in a direction of translation. For this purpose, the shuttle comprises two oblong holes 74 and 75 in which are respectively arranged two rollers 76 and 77 mounted rotating on two shafts fixed to the plate 23. To actuate alternately the rocker 34 in the two directions of rotation between its two positions stable angular, this shuttle comprises, at one end oriented towards a rear part of the rocker, a leaf spring 78 terminated by an actuating head 80 and extending, in its non-deformed position (rest position), along a thrust axis 70 parallel to the direction of translation and advantageously intercepting the pivot axis 58 of the control lever. Then, the rear part of the rocker is located on a side opposite to the first element 54 relative to the pivot axis 58, this rear part having a symmetrical profile with two actuating recesses 85 and 86 respectively located on the side and d other of an axis of symmetry 88, intercepting the pivot axis 58, and whose respective profiles are provided to receive the head actuating 80. The rear part of the rocker further has a projecting portion 82 which is arranged between the two actuating recesses and which has two symmetrical sides 83 and 84 ending respectively in the two actuating recesses. The axis of symmetry 88 of the aforementioned rear part passes substantially through the top of the protruding part 82.

Remarkably, as shown in Figures 5a to 5D , the shuttle 72 and the control lever 34 are arranged so that, when the lever 34 is in any one of its two control positions and the shuttle is pushed towards the lever by means of a pusher 90, the actuating head 80 first abuts against one (at the Figure 5A , the sidewall 84) of the two sides of the projecting part facing it (see Figure 5A ) and then slides along this side, elastically deforming the leaf spring 78, until it is housed in the actuating recess at the bottom of the recess in question (see Figure 5B ). Then, by continuing to push the shuttle along its direction of translation, the actuating head generates a pushing force F1 which produces a moment of force on the rocker enabling it to rotate in rotation at least beyond a middle angular position between said first and second angular positions (see Figure 5C ), so as to allow the tilting of the control rocker in the other of its two control positions (see Figure 5D ). By repeating this operation of actuation of the rocker, the actuation device of the control rocker allows the rocking of this control rocker alternately between its first and second stable angular positions corresponding to the two control positions of the control rocker.

It will be noted that a spring 92 is provided which exerts a restoring force on the shuttle 72. This spring can be replaced by a spring incorporated in a push button associated with the push button 90 if the latter is integral in translation with the push button. As will be seen later, the switching device according to the invention requires only a small pushing force on the pusher so that one can essentially determine the force that a user must apply to change the state of the chronograph mechanism by selecting the return force of the spring associated with the shuttle.

Here are some observations in relation to the preferred embodiment shown in the figures: - The fact that the pin 66 is located on the axis of symmetry 88 only constitutes a symmetrical advantageous variant for the positioning device 62; - The fact that the leaf spring 78 is arranged at rest (in its non-deformed state) on the thrust axis 70 of the shuttle represents an advantageous but not compulsory variant (indeed, a certain angle between them is possible); - The fact that the thrust axis, on which the leaf spring is located at rest, intercepts the pivot axis 58 and that the axis of symmetry 88 has an identical angular offset (in absolute value) with this axis of pushing in the two control positions of the rocker constitutes a preferred variant; - The fact that the alignment axis 56 is parallel to the direction of translation of the shuttle is a special non-mandatory case; - And the fact that the thrust axis 70 is coincident with the alignment axis 56 defines an advantageous but not compulsory case.

With particular reference to Figures 6A to 6D and 7 and in the light of the functioning of the magnetic system described above using the Figures 1 and 2 , the operation of the clutch device 30 will be described below. Figure 7 four torque curves are represented as a function of the angular position of the control lever 34, respectively of the angular position of the first element with high magnetic permeability 54 between the two stable positions of the control lever, respectively between the two control positions of element 54. For the embodiment described with reference to the figures, the 0 ° position corresponds to the second control position of the element 54 while the 20 ° position corresponds to the first control position of this element 54. In the 0 ° angular position of the rocker, the clutch device is engaged or brought into this engaged state. In the angular position 20 ° of the rocker, the clutch device is disengaged or brought into this disengaged state. These four curves represent the pairs acting, on the one hand, on the chronograph lever 38 and therefore on the switching member 36 (curves 100 and 102) and, on the other hand, on the control lever (curves 104 and 106) when the switching member is held (forcibly) either in its first its first stable position (curves 100 and 104), or in its second stable position (curves 102 and 106).

Whatever the position of the switching member, it can be seen that the torque produced by the magnetic force generated by the magnetic system, composed of the two magnets 50 and 52 and the two elements with high magnetic permeability 54 and 60, passes from a negative torque corresponding to a magnetic attraction force when the control lever occupies the angular position 0 ° to a positive torque corresponding to a magnetic repulsion force when this lever occupies the angular position 20 °. Thus, for the 0 ° angular position of the control lever, the torque range TR1 acting on the clutch member is entirely negative, while for the 20 ° angular position of this lever, the torque range TR2 acting on the clutch member is entirely positive. In conclusion, as revealed by the torque curves of the Figure 7 , the clutch device is arranged so that, when the first element 54 is in its second control position ( Figure 4 and Figure 6A ), the first and second magnets 50 and 52 generate between them a magnetic attraction force (magnetic attraction force) over the entire switching path of the first magnet, and so that, when this first element 54 is in its first control position ( Figure 3 and Figure 6C ), the first and second magnets generate between them a magnetic repulsive force (magnetic repulsive force) over the entire switching path.

In addition, the magnetic repulsion force is provided with an intensity and a range which are sufficient for it to actuate alone the switching member 36 between its first stable position and its second stable position, and then to maintain it in this second stable position; while the magnetic attraction force has an intensity and a range which are sufficient for it to actuate this switching element alone between its second stable position and its first stable position, and then to maintain it in this first stable position . Thus, no return spring associated with the switching member is necessary in this preferred embodiment.

The Figure 7 still shows an advantage of the switching device according to the invention. It is observed that the torque which must be exerted on the control lever is much lower than the torque which is exerted on the switching member (clutch lever 38). Thus, a user must provide less force on the pusher to trigger the clutch function, respectively the declutching function, in comparison with a conventional mechanical device.

It will be noted that, in another variant, the disengaged state and the engaged state are reversed so that the chronograph mechanism is driven when the control member is in one of its two control positions generating a magnetic repulsion force. , while it is stopped when this control member is in the other of its two control positions generating a magnetic attraction force.

The Figures 6A to 6D are given to show the variation of the magnetic force which intervenes on the magnet 50 integral with the clutch lever 38 as a function of the angular position of the lever lever command 34. The Figure 6A partially shows the clutch device 30 in its engaged state with the control lever in its stable clutch position. The magnetic force FM1 is a magnetic attraction force in the direction of the fixed magnet 52, this force being oriented substantially along the alignment axis 56 and has a relatively great intensity because the movable magnet 50 is located in face of the element with high magnetic permeability 54 (the longer of the two elements 54 and 60) and at a short distance from it, this element 54 also being at a short distance from the fixed magnet 52. The Figure 6B shows the transition to a disengaged state of the clutch device by tilting the control rocker clockwise. The magnetic force FM2 changes orientation when the lever 34 is pivoted during this passage and it becomes a magnetic repulsion force for the movable magnet 50, respectively for the clutch lever 38 carrying this magnet. The Figure 6C shows the control lever in its stable disengaging position with the element with high magnetic permeability 60 (the shorter of the two elements 54 and 60) substantially aligned on the alignment axis 56. The distance between the element 60 and the movable magnet 50 is relatively large and the magnetic repelling force FM3 is substantially oriented along the alignment axis. Finally, the Figure 6D shows the passage of the clutch device from a engaged state to a disengaged state during a pivoting of the lever 34 in a counterclockwise direction. The magnetic force FM4 again changes orientation during this passage to become a magnetic attraction force when the movable magnet 50 approaches the element 54. At the end of pivoting of the control rocker, there is again in the configuration of the Figure 6A . Thus, a complete cycle of the clutch device according to the invention is completed.

Claims (11)

1. Timepiece comprising a mechanism (24) able to switch between a first state and a second state, a device (30) for switching said mechanism between its first and second states and a device (32) for actuation of said switching device; the switching device comprising an operating member (34) actuated by said actuation device and a switching device (36), said switching device being arranged such that the switching member is capable of changing on demand from a first stable position, in which the mechanism is in its first state, to a second stable position, in which the mechanism is in its second state, and vice versa;
   said timepiece being characterized in that the timepiece includes:

   - a first bipolar magnet (50) which is fixed to said switching member so as to undergo, when said switching member changes from the first stable position to the second stable position, a motion along a switching path between a first switching position and a second switching position, and vice versa,

   - a second bipolar magnet (52) which is fixed to a support of the switching device so as to continually offer a magnetic interaction with the first bipolar magnet between the first and second switching positions thereof,

   - at least a first highly magnetically permeable element (54) at least partially forming said operating member;

   in that said operating member is arranged so that, when it is repeatedly actuated by the actuation device, the first highly magnetically permeable element (54) is subjected to a back-and-forth motion between a first operating position and a second operating position; and in that the switching device is arranged so that, when the first highly magnetically permeable element is in the first operating position thereof, the first and second magnets generate therebetween a force of magnetic repulsion over substantially the entire said switching path and so that, when the first highly magnetically permeable element is in the second operating position thereof, the first and second magnets generate therebetween a force of magnetic attraction on at least one part of the switching path, said part being located on the side of the second bipolar magnet.
2. Timepiece according to claim 1, characterized in that the force of magnetic repulsion has an intensity and a range that are sufficient for the force of magnetic repulsion alone to actuate the switching member (36) between the first stable position and the second stable position thereof and then to hold said member in said second stable position, whereas the force of magnetic attraction has an intensity and a range that are sufficient for said force of magnetic attraction alone to actuate the switching member between the second stable position and the first stable position thereof and then to hold said member in said first stable position.
3. Timepiece according to claim 1 or 2, characterized in that said operating member (34) is formed by an operating lever which is pivoted so that said first highly magnetically permeable element undergoes a rotation between a first angular position and a second angular position respectively defining the first operating position and the second operating position; in that, when the first highly magnetically permeable element (54) is in the second angular position, said first element is substantially located on an axis of alignment (56), defined by the magnetic axis of the second bipolar magnet, so that it is substantially between the first and second bipolar magnets: whereas, in the first angular position thereof, the first highly magnetically permeable element is remote from said axis of alignment.
4. Timepiece according to claim 3, characterized in that the switching path of the first bipolar magnet (50) is substantially coincident with said axis of alignment and said first bipolar magnet is arranged with its magnetic axis substantially oriented along said axis of alignment, the first and second bipolar magnets being arranged with opposite polarities.
5. Timepiece according to claim 3 or 4, characterized in that the operating lever comprises an opening (68) between the pivoting axis (58) thereof and the first highly magnetically permeable element, said second magnet (52) being arranged in said opening at least when the operating lever is in the second angular position thereof, said opening having a contour arranged so that the operating lever can freely undergo rotation between the first and second angular positions thereof.
6. Timepiece according to any of claims 3 to 5, characterized in that the operating lever includes a pin (66) associated with a positioning spring (64) which has two positioning hollows respectively defining the first and second angular positions of the lever when the pin is housed in succession in said two positioning hollows.
7. Timepiece according to any of claims 3 to 6, characterized in that said actuation device includes a shuttle (72) guided in translation in a given direction of translation, said shuttle comprising, at one end oriented towards a rear part of the lever, a strip-spring (78) ending in an actuation head (80) and extending, in the non-deformed position thereof, along a thrust axis (70) which is parallel to said direction of translation and substantially intercepting the pivoting axis of the operating lever; in that said rear part of the lever is located on a side opposite to said first highly magnetically permeable element relative to said pivoting axis, said rear part having a symmetrical profile with two actuation hollows (85, 86) respectively located on either side of an axis of symmetry (88) substantially intercepting said pivoting axis, and whose respective profiles are arranged to receive the actuation head, a protruding portion (82) being arranged between the two actuation hollows and having two symmetrical flanks (83, 84) respectively ending in the two actuation hollows, said axis of symmetry of the rear part passing substantially through the tip of the protruding portion; and in that the shuttle and the operating lever are arranged so that, when the shuttle is pushed in the direction of the operating lever, the actuation head slides first along one of the two flanks of the protruding portion facing said head, elastically deforming said strip-spring, until said head lodges inside the actuation hollow at the bottom of said flank, and then said actuation head generates a moment of force on the lever allowing it to be driven in rotation at least past a median angular position between said first and second angular positions, so as to allow the operating lever to tip alternately between the first and second angular positions thereof.
8. Timepiece according to any of the preceding claims, characterized in that said operating member further includes a second highly magnetically permeable element (60) arranged to be substantially aligned with said first and second bipolar magnets when the first highly magnetically permeable element is in the first operating position thereof.
9. Timepiece according to claim 8, characterized in that the second highly magnetically permeable element (60) is arranged to be located closer to one or other of the first and second bipolar magnets regardless of the position of the first bipolar magnet along said switching path.
10. Timepiece according to any of the preceding claims, characterized in that said switching member is formed by a coupling device (30) including a coupling lever (38) to which the first magnet is fixed, the first and second stable positions of the coupling lever being defined respectively by two stops (44, 45) between which an arm of said coupling lever passes.
11. Timepiece according to claim 10, characterized in that said mechanism is a chronograph mechanism, the actuation device comprising a pusher (90) able to be actuated by a timepiece user.

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