CH711946A2

CH711946A2 - Clock mechanism comprising a pivoting member provided with magnetic return means.

Info

Publication number: CH711946A2
Application number: CH01889/15A
Authority: CH
Inventors: Légeret Benoît; Sarchi Davide; Dauby Sylvain; Zaugg Alain
Original assignee: Montres Breguet Sa
Priority date: 2015-12-22
Filing date: 2015-12-22
Publication date: 2017-06-30

Abstract

Le mécanisme horloger selon l’invention comprend un mobile tournant (27), un support, un organe pivotant (15a, 15b) monté sur ce support, et des moyens de rappel pour rappeler une partie (19) de l’organe pivotant contre une surface du mobile tournant. Les moyens de rappel comportent un premier aimant (21) porté par l’organe pivotant et un deuxième aimant (25) porté par le support. Les premier et deuxième aimants sont agencés de manière que, dans un première position relative, l’interaction de leurs champs magnétiques respectifs engendre une force magnétique orientée de manière à rappeler ladite partie de l’organe pivotant en direction de ladite surface du mobile tournant. Au moins un des premier et deuxième aimants est agencé pour permettre d’inverser sa polarité et ainsi le sens de la force magnétique agissant sur l’organe pivotant. Cette inversion est réalisée de préférence à l’aide d’un outil par un horloger.The watch mechanism according to the invention comprises a rotating wheel (27), a support, a pivoting member (15a, 15b) mounted on this support, and return means for biasing a portion (19) of the pivoting member against a rotating mobile surface. The return means comprise a first magnet (21) carried by the pivoting member and a second magnet (25) carried by the support. The first and second magnets are arranged such that, in a first relative position, the interaction of their respective magnetic fields generates a magnetic force oriented to return said portion of the pivoting member towards said surface of the rotating wheel. At least one of the first and second magnets is arranged to reverse its polarity and thus the direction of the magnetic force acting on the pivoting member. This inversion is preferably performed with the aid of a tool by a watchmaker.

Description

DescriptionDescription

DOMAINE DE L’INVENTIONFIELD OF THE INVENTION

[0001] La présente invention concerne généralement les mécanismes horlogers comprenant un mobile tournant, un support, un organe monté pivotant sur le support et des moyens de rappel magnétique pour rappeler une partie de l’organe pivotant contre une surface du mobile tournant. La présente invention concerne plus particulièrement un tel mécanisme dans lequel les moyens de rappel comportent un premier aimant porté par l’organe pivotant et un deuxième aimant porté par le support séparément de l’organe pivotant, le premier aimant et le deuxième aimant étant agencés de manière que, dans une première position relative du premier aimant et du deuxième aimant, l’interaction des champs magnétiques respectifs de ces derniers engendre une force agissant sur l’organe pivotant et orientée de manière à rappeler ladite partie de l’organe pivotant en direction de la surface du mobile tournant.The present invention generally relates to watch mechanisms comprising a rotating mobile, a support, a pivotally mounted member on the support and magnetic return means for biasing a portion of the pivoting member against a rotating surface of the mobile. The present invention relates more particularly to such a mechanism in which the return means comprise a first magnet carried by the pivoting member and a second magnet carried by the support separately from the pivoting member, the first magnet and the second magnet being arranged with in a first relative position of the first magnet and the second magnet, the interaction of the respective magnetic fields of the latter generates a force acting on the pivoting member and oriented so as to bias said portion of the pivoting member towards of the rotating mobile surface.

ART ANTERIEURPRIOR ART

[0002] On connaît déjà des mécanismes horlogers qui correspondent à la définition ci-dessus. Ainsi, la figure 15 du document de brevet FR 1 276 734 montre une partie d’un mécanisme de remontoir automatique, cette partie servant à la conversion du mouvement de rotation d’un mobile tournant en mouvements alternés d’un organe pivotant. Selon l’exemple illustré, le mobile tournant avec lequel coopère l’organe pivotant est constitué par une came trilobée et les moyens de rappel pour rappeler une partie de l’organe pivotant contre une surface du mobile tournant comporte deux aimants permanents.[0002] Clock mechanisms are already known which correspond to the definition above. Thus, FIG. 15 of the patent document FR 1 276 734 shows part of an automatic winding mechanism, this part serving for the conversion of the rotational movement of a mobile rotating in alternating movements of a pivoting member. According to the illustrated example, the rotating wheel with which the pivoting member cooperates is constituted by a trilobal cam and the return means for biasing a part of the pivoting member against a surface of the rotating wheel comprises two permanent magnets.

[0003] Conformément aux explications ci-dessus, l’invention concerne donc des mécanismes horlogers dans lesquels les moyens de rappel n’opèrent pas grâce à un ressort, mais au moyen d’une paire d’aimants. L’utilisation de tels moyens de rappel présente notamment l’avantage d’éviter les problèmes liés à la fatigue du ressort. En effet, lorsqu’un ressort est soumis à des sollicitations répétées à de multiples reprises, des microfissures risquent de se former et d’entraîner une baisse du coefficient d’élasticité, voire même la rupture du ressort.In accordance with the explanations above, the invention therefore relates to watch mechanisms in which the biasing means do not operate through a spring, but by means of a pair of magnets. The use of such return means has the advantage of avoiding the problems related to fatigue of the spring. Indeed, when a spring is repeatedly subjected to stress repeatedly, microcracks may form and cause a drop in the coefficient of elasticity, or even the rupture of the spring.

[0004] Les mécanismes horlogers comprenant des moyens de rappel comportant plusieurs aimants permanents présentent toutefois également certains inconvénients. En effet, les aimants permanents doivent être agencés à proximité les uns des autres. Dans ces conditions, l’omniprésence d’une force d’interaction magnétique entre les aimants rend délicate l’opération d’assemblage de tels mécanismes. Elle complique également leur éventuel démontage et leur ajustement.[0004] The clock mechanisms comprising return means comprising several permanent magnets also have certain disadvantages, however. Indeed, the permanent magnets must be arranged close to each other. Under these conditions, the omnipresence of a magnetic interaction force between the magnets makes the assembly operation of such mechanisms difficult. It also complicates their eventual dismantling and adjustment.

BREF EXPOSE DE L’INVENTIONBRIEF SUMMARY OF THE INVENTION

[0005] Un but de la présente invention est de remédier aux inconvénients de l’art antérieur en fournissant un mécanisme horloger conformes à la définition donnée en préambule et dont le mobile tournant et les pièces coopérant avec lui puissent être aisément assemblés lors du montage du mécanisme et retirés facilement pour contrôle, nettoyage ou réparation et être réassemblés sans qu’il soit nécessaire d’effectuer un réglage. La présente invention atteint ce but en fournissant un mécanisme horloger selon la revendication 1 annexée.An object of the present invention is to overcome the disadvantages of the prior art by providing a watch mechanism according to the definition given in the preamble and whose rotating wheel and the parts cooperating with it can be easily assembled during assembly of the and removed easily for inspection, cleaning or repair and reassembled without the need for adjustment. The present invention achieves this goal by providing a clock mechanism according to the appended claim 1.

[0006] Conformément à l’invention, au moins un desdits premier et deuxième aimants est agencé pour permettre d’inverser sa polarité, et par voie de conséquence, le sens de la force magnétique agissant sur l’organe pivotant. Autrement dit, si la force magnétique est une force attractive, l’inversion de la polarité d’un des aimants la changera en une force répulsive. Inversement, si la force magnétique est une force répulsive, l’inversion de la polarité d’un des aimants engendre alors une force attractive. On comprend donc que si la polarité d’un aimant d’un mécanisme horloger conforme à l’invention est inversée à un moment donné, la force qui avait jusque-là pour effet de rappeler une partie de l’organe pivotant contre une surface du mobile tournant change de sens, écartant ainsi l’organe pivotant du mobile tournant.According to the invention, at least one of said first and second magnets is arranged to allow to reverse its polarity, and consequently, the direction of the magnetic force acting on the pivoting member. In other words, if the magnetic force is an attractive force, reversing the polarity of one of the magnets will change it into a repulsive force. Conversely, if the magnetic force is a repulsive force, the inversion of the polarity of one of the magnets then generates an attractive force. It is therefore understood that if the polarity of a magnet of a clockwork mechanism according to the invention is reversed at a given moment, the force which hitherto had the effect of reminding a part of the pivoting member against a surface of the mobile rotating changes direction, thus removing the pivoting member of the rotating mobile.

[0007] Conformément à une variante avantageuse de l’invention, le deuxième aimant est formé de manière à lui permettre de coopérer avec un outil pour permettre de le tourner sur lui-même. Un avantage de cette variante est de permettre à un horloger de varier l’interaction magnétique dans le système magnétique en question et notamment de changer le sens de la force magnétique sur l’organe pivotant pour maintenir momentanément écarté l’organe pivotant du mobile tournant, facilitant ainsi un montage ou un démontage du mécanisme horloger.According to an advantageous variant of the invention, the second magnet is formed so as to allow it to cooperate with a tool to allow it to turn on itself. An advantage of this variant is that it enables a watchmaker to vary the magnetic interaction in the magnetic system in question and in particular to change the direction of the magnetic force on the pivoting member in order to keep momentarily the pivoting member of the rotating mobile, thus facilitating assembly or disassembly of the watch mechanism.

BREVE DESCRIPTION DES FIGURESBRIEF DESCRIPTION OF THE FIGURES

[0008] D’autres caractéristiques et avantages de la présente invention apparaîtront à la lecture de la description qui va suivre, donnée uniquement à titre d’exemple non limitatif, et faite en référence aux dessins annexés dans lesquels: la fig. 1 est une vue en plan de dessus d’un mécanisme de remontage automatique pour montre qui constitue un premier mode de réalisation particulier du mécanisme horloger de l’invention; la fig. 2 est une vue en perspective agrandie du mécanisme de remontage automatique de la fig. 1, la masse oscillante ayant été omise; la fig. 3 est une vue partielle en plan de dessus du mécanisme de remontage automatique des fig. 1 et 2 montrant plus en détail l’agencement de la bascule, de deux cliquets et de la roue à röchet; la fig. 4 est une vue partielle semblable à la fig. 3 et qui montre un mécanisme de remontage automatique pour montre constituant un deuxième mode de réalisation particulier du mécanisme horloger de l’invention.Other features and advantages of the present invention will appear on reading the description which follows, given solely by way of non-limiting example, and with reference to the accompanying drawings in which: FIG. 1 is a plan view from above of an automatic winding mechanism for a watch which constitutes a first particular embodiment of the watchmaking mechanism of the invention; fig. 2 is an enlarged perspective view of the automatic winding mechanism of FIG. 1, the oscillating weight having been omitted; fig. 3 is a partial plan view from above of the automatic winding mechanism of FIGS. 1 and 2 showing in more detail the arrangement of the rocker, two pawls and the ratchet wheel; fig. 4 is a partial view similar to FIG. 3 and which shows an automatic winding mechanism for a watch constituting a second particular embodiment of the watch mechanism of the invention.

DESCRIPTION DETAILLEE DE MODES DE REALISATIONDETAILED DESCRIPTION OF EMBODIMENTS

[0009] Les fig. 1, 2 et 3 sont des illustrations d’un premier mode de réalisation particulier du mécanisme horloger de l’invention. Dans l’exemple illustré, le mécanisme horloger (globalement référencé 1) est un mécanisme de remontage automatique bidirectionnel pour mouvement d’horlogerie. Ce mécanisme comporte une masse oscillante 3 et une came excentrique 5 montée fixe sur la masse oscillante, en position coaxiale, de manière que la came 5 participe solidairement au mouvement d’oscillation de la masse 3. Comme le montre la fig. 1, l’excentrique présente la forme d’un disque ovale possédant un centre de symétrique 2 par lequel passe son axe de rotation. On comprendra toutefois, que de manière connue en soi, la came excentrique pourrait tout aussi bien avoir une autre forme. Par exemple, la forme d’une ellipse ou d’un cœur.Figs. 1, 2 and 3 are illustrations of a first particular embodiment of the clock mechanism of the invention. In the illustrated example, the clock mechanism (generally referenced 1) is a bidirectional automatic winding mechanism for a watch movement. This mechanism comprises an oscillating mass 3 and an eccentric cam 5 fixedly mounted on the oscillating mass, in coaxial position, so that the cam 5 participates solidarily in the oscillation movement of the mass 3. As shown in FIG. 1, the eccentric has the shape of an oval disk having a symmetrical center 2 through which its axis of rotation passes. It will be understood, however, that in a manner known per se, the eccentric cam could just as well have another shape. For example, the shape of an ellipse or a heart.

[0010] En se référant plus particulièrement à la fig. 2, on peut voir que le mécanisme illustré comporte une bascule 7 pivotée autour d’un axe 9. La came excentrique 5 est en contact avec la bascule par l’intermédiaire de deux galets de roulement 11 montés chacun sur un tenon 13 de la bascule. Lorsque la masse 3 pivote dans un sens ou dans l’autre, l’interaction entre la came excentrique et les deux galets a pour effet de communiquer un mouvement oscillant à la bascule 7.Referring more particularly to FIG. 2, it can be seen that the illustrated mechanism comprises a rocker 7 pivoted about an axis 9. The eccentric cam 5 is in contact with the rocker by means of two rollers 11 each mounted on a pin 13 of the rocker . When the mass 3 pivots in one direction or the other, the interaction between the eccentric cam and the two rollers has the effect of imparting an oscillating movement to the rocker 7.

[0011] La bascule 7 du mécanisme horloger qui fait l’objet de présent exemple porte deux organes pivotant (respectivement référencés 15a et 15b) qui sont pivotes sur la bascule autour de deux axes distincts 17a, 17b. Chacun des organes pivotant a la forme d’un levier du premier genre avec deux bras qui s’étendent de part et d’autre de l’axe de pivotement. Un premier bras se termine par un bec 19 et est agencé pour servir de cliquet. Ensuite, le deuxième bras porte un aimant (ci-après premier aimant 21). Le premier aimant est de préférence monté dans un logement 23 prévu à cet effet.The latch 7 of the watch mechanism which is the subject of this example carries two pivoting members (respectively referenced 15a and 15b) which are pivoted on the latch around two separate axes 17a, 17b. Each of the pivoting members has the form of a lever of the first kind with two arms which extend on either side of the pivot axis. A first arm ends with a spout 19 and is arranged to serve as a ratchet. Then, the second arm carries a magnet (hereinafter first magnet 21). The first magnet is preferably mounted in a housing 23 provided for this purpose.

[0012] En se référant toujours aux figures, on peut voir en outre que la bascule 7 porte un autre aimant (ci-après deuxième aimant 25) monté séparément des deux organes pivotant 15a, 15b. Dans l’exemple représenté, les trois aimants 21 et 25 sont sensiblement alignés et situés dans un plan perpendiculaire à l’axe de rotation 2 de la masse oscillante 3. Le deuxième aimant est disposé à une certaine distance des deux premiers aimants 21 sur la bascule 7. On peut voir en outre que les aimants 21 et 25 ont la forme de disque et que leur direction de polarisation correspond sensiblement à la direction d’alignement des aimants dans le plan perpendiculaire à l’axe 2. En se référant plus particulièrement à la fig. 3, on peut noter que les trois aimants sont disposés de manière alternée en ce qui concerne le sens de leur polarisation. Autrement dit, les deux premiers aimants 21 sont polarisés dans le même sens, alors que le deuxième aimant 25, qui est intercalé entre les deux premiers aimants, est polarisé en sens contraire. Dans ces conditions, les aimants se repoussent, et une force magnétique de répulsion se manifeste sous la forme d’un couple de rappel exercé dans le sens antihoraire sur l’organe de pivotement 15a et par un couple de rappel exercé dans le sens horaire sur l’organe pivotant 15b.Still referring to the figures, it can be seen further that the latch 7 carries another magnet (hereinafter second magnet 25) mounted separately from the two pivoting members 15a, 15b. In the example shown, the three magnets 21 and 25 are substantially aligned and located in a plane perpendicular to the axis of rotation 2 of the oscillating mass 3. The second magnet is disposed at a distance from the first two magnets 21 on the flip-flop 7. It can further be seen that the magnets 21 and 25 are disk-shaped and that their polarization direction corresponds substantially to the alignment direction of the magnets in the plane perpendicular to the axis 2. Referring more particularly in fig. 3, it can be noted that the three magnets are alternately arranged with respect to the direction of their polarization. In other words, the first two magnets 21 are polarized in the same direction, while the second magnet 25, which is interposed between the first two magnets, is polarized in the opposite direction. Under these conditions, the magnets repel, and a magnetic repulsion force is manifested in the form of a return torque exerted counterclockwise on the pivot member 15a and by a return torque exerted clockwise on the pivoting member 15b.

[0013] Le mécanisme horloger 1 comprend encore un mobile tournant 27. Dans l’exemple représenté, le mobile tournant est une roue à röchet. De manière connue, la roue à röchet est agencée pour être entraînée par les deux cliquets 15a et 15b. Dans le mode de réalisation illustré, les deux cliquets sont rappelés contre le röchet de la roue à röchet 27 en sens contraire. Ainsi, lorsque la bascule 7 pivote autour de l’axe 9 dans le sens horaire, le cliquet 15a est tiré et dégrène de la denture de la roue à röchet 27, tandis que le cliquet 15b, qui est également tiré, entraîne la roue à röchet. Inversement, lorsque la bascule 7 pivote autour de l’axe 9 dans le sens antihoraire, le cliquet 15a est poussé et entraîne la roue à röchet, tandis que le cliquet 15b, qui est également poussé, dégrène de la denture de la roue à röchet. De manière classique, la roue à röchet 27 est agencée pour entraîner l’arbre d’un barillet par l’intermédiaire d’un rouage de manière à armer le ressort de barillet.The watch mechanism 1 further comprises a rotating wheel 27. In the example shown, the rotating wheel is a wheel röchet. In known manner, the ratchet wheel is arranged to be driven by the two pawls 15a and 15b. In the illustrated embodiment, the two pawls are biased against the ratchet of the ratchet wheel 27 in the opposite direction. Thus, when the rocker 7 pivots about the axis 9 in the clockwise direction, the pawl 15a is pulled out of and off the teeth of the ratchet wheel 27, while the ratchet 15b, which is also pulled, drives the wheel to ratchet. Conversely, when the rocker 7 pivots about the axis 9 counterclockwise, the pawl 15a is pushed and drives the wheel röchet, while the pawl 15b, which is also pushed, out of the teeth of the wheel röchet . Conventionally, the ratchet wheel 27 is arranged to drive the shaft of a barrel by means of a gear train so as to arm the mainspring.

[0014] Conformément à l’invention, un au moins des premier et deuxième aimants 21,25 est agencé pour permettre de changer la direction ou le sens de sa polarité et varier ainsi la force magnétique agissant sur l’organe pivotant 15a ou 15b. Dans la variante décrite ici, le deuxième aimant 25 est agencé de manière à pouvoir être pivoté de 180° par rapport à la bascule 7 sur laquelle il est monté, ce qui permet de changer le sens de la polarité de ce deuxième aimant. En se référant en particulier à la fig. 3, on peut voir que le deuxième aimant, qui est logé dans une cavité de la bascule 7, présente la forme d’une tête de vis à fente. La fente est prévue pour permettre à un horloger de faire tourner l’aimant en se servant d’un tournevis. Conformément à une variante, le deuxième aimant est monté dans un logement tournant (non représenté) qui est lui-même logé dans une cavité de la bascule. Un avantage de cette variante est de permettre de tourner l’aimant sans que ce dernier ne frotte contre la cavité dans laquelle il est logé; ce qui permet d’éviter que cet aimant ne soit endommagé lors de son pivotement.According to the invention, at least one of the first and second magnets 21,25 is arranged to change the direction or direction of its polarity and thus vary the magnetic force acting on the pivoting member 15a or 15b. In the variant described here, the second magnet 25 is arranged to be pivoted by 180 ° relative to the rocker 7 on which it is mounted, which allows to change the direction of the polarity of the second magnet. Referring in particular to FIG. 3, it can be seen that the second magnet, which is housed in a cavity of the rocker 7, has the shape of a slotted screw head. The slot is intended to allow a watchmaker to rotate the magnet using a screwdriver. According to a variant, the second magnet is mounted in a rotating housing (not shown) which is itself housed in a cavity of the rocker. An advantage of this variant is to allow the magnet to rotate without the latter rubbing against the cavity in which it is housed; which makes it possible to prevent this magnet from being damaged during its pivoting.

[0015] On peut comprendre que si on tourne le deuxième aimant 25 de 180°, les trois aimants 21,25 se trouvent polarisés dans le même sens.It can be understood that if we turn the second magnet 25 of 180 °, the three magnets 21,25 are polarized in the same direction.

[0016] Dans ces conditions, les aimants s’attirent au lieu de se repousser. Ainsi, une force magnétique d’attraction se manifeste sous la forme d’un couple exercé dans le sens horaire sur l’organe pivotant 15a et par un couple de rappel exercé dans le sens antihoraire sur l’organe pivotant 15b. Les deux cliquets s’écartent ainsi de la roue à röchet 27. Grâce à cette caractéristique de l’invention, les pièces du mécanisme horloger peuvent être premièrement montées aisément etUnder these conditions, the magnets attract instead of repelling. Thus, a magnetic attraction force is manifested in the form of a torque exerted in the clockwise direction on the pivoting member 15a and by a return torque exerted counterclockwise on the pivoting member 15b. The two ratchets thus depart from the ratchet wheel 27. Thanks to this feature of the invention, the parts of the watch mechanism can be mounted first easily and

Claims

then easily removed for inspection, cleaning or repair and finally reassembled. On the other hand, the invention offers a great advantage when it is necessary to disarm the barrel, for example to proceed with the replacement of the mainspring. Indeed, as we have seen, the fact of reversing the polarity of the second magnet makes it possible to maintain the two pawls 15a, 15b disengaged from the ratchet wheel, and therefore from the mainspring. The invention has yet another advantage because the possibility of rotating a magnet offered by the invention allows to vary the direction of the magnetization axis of the magnet and thus the interaction with the other magnet system concerned, in particular to vary the intensity of the magnetic force between the two magnets. It is therefore possible to adjust the intensity of the magnetic force acting on the pivoting member. Such a fine adjustment of the magnetic force may be important to optimize the function, in particular the intensity of the restoring force exerted on the pivoting member. In a first variant, in particular for a pawl or a jumper, the magnet arranged rotating on the support forms an eccentric, that is to say that the magnet is not centered on the axis of rotation of the -this. Thus, by varying the direction of the magnet, it is approached or removed from the magnet carried by the rotating member. In a second variant, the magnet does not have a plane (ie in a general plane perpendicular to its axis of rotation) a cylindrical or square shape but another shape, for example rectangular or elliptical. As for the first variant, such a configuration makes it possible to vary the intensity of the force exerted in the magnetic system in question. FIG. 4 is a partial view, similar to FIG. 3, an automatic winding mechanism for a watch constituting a second embodiment of the watch mechanism of the invention. It can be seen that the mechanism of FIG. 4 comprises a flip-flop 107 (only part of which is visible) pivoted about an axis 109. It will be understood that, in a manner similar to that explained in connection with the first embodiment, when the oscillating mass (not shown ) pivots in one direction or the other, the interaction between the eccentric cam (not shown) and the two rollers 11 (not shown) has the effect of communicating an oscillating movement, back and forth to the rocker 107. [0019] The rocker 107 carries two pivoting members (respectively referenced 115a and 115b) which are pivoted on the rocker around two separate axes 117a, 117b. It will be noted that, contrary to the case of the first embodiment, the arrangement of the pivoting members in FIG. 4 is asymmetrical. The pivoting member 115a has the shape of a lever of the third kind with a single arm extending from pivoting axis 117a, while the pivoting member 115b has the shape of a lever of the first kind with two arms which extend on either side of the pivot axis 117b. A first arm of the pivoting member 115b, which terminates in a spout 119, is arranged to serve as a pawl. On the other hand, the second arm carries a magnet (hereinafter first magnet 121). The pivoting member 115a is also arranged to serve as a pawl, its single arm also ending in a spout 119, and it also carries a magnet (hereinafter first magnet 121) which is disposed between the pivot axis 117a and the beak 119. It will be understood that it is precisely this intermediate position of the magnet which makes the pivoting member 115a a lever of the third kind. Still referring to FIG. 4, it can be seen further that the rocker 107 carries another magnet (hereinafter second magnet 125) which is separated from the two pivoting members 115a, 115b. As was already the case with the first embodiment, the three magnets 121 and 125 are substantially aligned and located in a plane perpendicular to the axis of rotation of the rocker. In addition, the second magnet is disposed on the rocker 107 between the two magnets 121 at a distance therefrom so as to prevent the magnets from colliding during the operation of the automatic winding mechanism. Again, their polarization direction substantially corresponds to their alignment direction. The first magnet mounted on the pivoting member 115b and the second magnet 125 are polarized in the same direction. Under these conditions, these two magnets attract and the magnetic attraction force is manifested as a return torque exerted counterclockwise on the pivoting member 115b. Similarly, the first magnet mounted on the pivoting member 115a is polarized in the same direction as the second magnet 125. Thus, it is attracted by this second magnet. The magnetic attraction force between the first magnet mounted on the pivoting member 115a and the second magnet 125 is in the form of a biasing torque exerted counterclockwise on the pivoting member 115a. It will further be understood that various modifications obvious to one skilled in the art can be made to the embodiments which are the subject of the present description, without departing from the scope of the present invention defined by the appended claims. In particular, the present invention is not limited to an automatic winding mechanism. Indeed, the skilled person knows in particular many other clock applications in which wheels and ratchets or jumpers are implemented. The present invention is capable of being easily adapted to each of these applications. On the other hand, the ratchets and the jumpers are naturally not the only examples of pivoting members capable of being arranged to cooperate with a rotating mobile. Examples other than pawls include, but are not limited to, cam control mechanisms, hammer reset mechanisms, mating clutch mechanisms, and perpetual calendar rocking mechanisms. claims

1. Watchmaking mechanism comprising a rotating mobile (27), a support, a member (15a, 15b; 115a, 115b) pivotally mounted on the support, and return means for biasing a portion (19) of the pivoting member against a rotating surface of the mobile, the return means comprising a first magnet (21; 121) carried by the pivoting member and a second magnet (25; 125) carried by the support separately from the pivoting member, the first magnet and the second magnet being arranged such that, in a first relative position of the first magnet and the second magnet, the interaction of the respective magnetic fields of these first and second magnets generates a magnetic force acting on said pivoting member which is oriented so as to recall said portion (19) of the pivoting member towards said surface of the rotating wheel, characterized in that at least one of said first and second magnets is arranged to allow to change the direction or the direction of its polarity and thus vary said magnetic force acting on the pivoting member.

2. Watchmaker mechanism according to claim 1, characterized in that said at least one of said first and second magnet is arranged to allow it to rotate on itself so as to reverse its polarity.

3. Watchmaking mechanism according to claim 2, characterized in that said at least one of said first and second magnets is arranged to be rotated by 180 ° about an axis perpendicular to its axis of polarization.

4. Watchmaker mechanism according to claim 2 or 3, characterized in that said at least one of said first and second magnets comprises the second magnet.

5. Watch mechanism according to claim 4, characterized in that the second magnet (25; 125) is shaped so as to enable it to cooperate with a tool to reverse its polarity.

6. Watchmaking mechanism according to claim 4 or 5, characterized in that the support comprises a pivoting housing arranged to receive the second magnet (25; 125).

7. Watchmaking mechanism according to one of the preceding claims, characterized in that the rotating wheel (27) comprises a wheel röchet and in that the pivoting member (15a, 15b, 125a, 125b) comprises a pawl.

8. Watchmaking mechanism according to claim 7, characterized in that the watch mechanism and an automatic winding mechanism comprising a rocker (7; 107) forming said support, the pawl (15a, 15b; 125a, 125b) being pivoted on the rocker .

9. Watch mechanism according to claim 8, characterized in that it comprises two pawls (15a and 15b, 125a and 125b), pivotally mounted about two separate axes (17a and 17b, 117a and 117b) on the rocker (7; 107), one of the two pawls being provided with said first magnet and the other of these two pawls being provided with a third magnet arranged relative to said second magnet in a manner similar to said first magnet.