EP3486735A1 - Second reset clock mechanism with snail cam - Google Patents

Abstract

The invention relates to a clock mechanism (22) for resetting the second, which comprises:
- A tree (17) seconds;
- A needle (15) second hand;
- A cam (23) forming a spiral cam path (24) which spirals around the second shaft (17) from an inner end (26) to an outer end (27) connected between they by a surface (28) of radial abutment;
- A hammer (29) carrying a cam follower (30) rotatably mounted about a hammer axis (A3) between a disengaged position in which the cam follower (30) is moved away from the cam path (24). and an engaged position in which the cam follower (30) bears on the cam path (24);
- A non-return ratchet system comprising a toothed wheel (41) and a ratchet (42) which engages the toothed wheel (41).

Description

Technical area

The invention relates to the field of watchmaking. It concerns, more precisely, a watch mechanism for resetting the second and a watch equipped with such a mechanism.

Technological background

• dans la plupart des montres à chronographe,
• et dans certaines montres pourvues d'une aiguille trotteuse (également appelée aiguille des secondes, ou plus simplement trotteuse) et dont le réglage de l'heure est accompagné d'une remise à zéro automatique de la trotteuse.

We can find a mechanism to reset the second:

• in most chronograph watches,
• and in some watches provided with a second-hand hand (also called seconds hand, or more simply second hand) and whose time setting is accompanied by an automatic reset of the second hand.

• une came solidaire en rotation de l'arbre des secondes et dont un bord périphérique forme un chemin de came ;
• un marteau portant un suiveur de came, ce marteau étant monté en rotation autour d'un axe de marteau entre une position débrayée dans laquelle le suiveur de came est écarté du chemin de came, et une position embrayée dans laquelle le suiveur de came est en appui sur le chemin de came pour produire un couple moteur sur l'arbre des secondes.

Classically, such a mechanism comprises (in addition to the second-hand hand and its second-hand shaft):

• a cam integral in rotation with the seconds shaft and a peripheral edge of which forms a cam path;
• a hammer carrying a cam follower, which hammer is rotatably mounted about a hammer axis between a disengaged position in which the cam follower is moved away from the cam path, and an engaged position in which the cam follower is in press on the cam path to produce a motor torque on the seconds shaft.

The cam usually has a heart shape, which is why it is called simply "heart", as it appears in the reference manual of IT. Reymondin et al, "Theorie d'horlogerie", Federation of Technical Schools, 2015 edition, p.238 .

In chronographs, the hammer is a complex piece with several cam followers that strike several respective cams, integral with the hour hand, the minute hand, the second hand (and, more occasionally, a tenth needle).

In the automatic reset watches of the second hand, as described in the European patent EP2224294 (Glasshütte) the hammer is of simpler form but the principle is the same.

In all cases, the cam follower is usually formed by one end of the hammer in the shape of a horse shoe, which comes, end of stroke (angular or linear), against a double boss formed on the heart to maintain in a stable position corresponding to the reset of the second hand.

This type of mechanism, very widespread, however, suffers from several disadvantages.

First, the position of the second hand during the reset is, in most cases, rather random and lacks precision. This is particularly detrimental in the case of a jumping needle, which is supposed to be every second in a precise angular position (each angular position being spaced from the next 6 °).

Secondly, given the respective geometry of the core and the hammer, the friction forces at their interface are not constant. This results in non-uniform wear of these parts, detrimental to the long-term reliability of the mechanism.

Third, in certain angular positions of the core, the hammer rubs on it by a sharp edge, as illustrated in FIG.11.29 of the aforementioned manual, which increases the stress concentration, wear and mechanical fatigue of these parts.

Fourthly, the momentum acquired by the heart during its rotation causes it not to be immediately blocked at the end of the race by the support of the end of the hammer in the seconds tree, but remains, before s immobilize, animated by damped oscillations which impede the perception of precision expected by an informed user.

Fifth, the complexity of known mechanisms makes them cumbersome and time-consuming.

A first objective is to propose a mechanism for resetting the second which provides a precise position of the second hand, exactly opposite a predetermined graduation of the dial (typically a twelve-hour index).

A second objective with greater reliability, and therefore longer life.

A third objective is to propose a mechanism for resetting the second architecture simpler (and therefore less cumbersome, lighter and easier to manufacture) than the known mechanisms.

Summary of the invention

• un arbre des secondes ;
• une aiguille trotteuse solidaire en rotation de l'arbre des secondes ;
• une came solidaire en rotation de l'arbre des secondes et dont un bord périphérique forme un chemin de came ;
• un marteau pourvu d'un suiveur de came, ce marteau étant monté en rotation autour d'un axe de marteau entre une position débrayée dans laquelle le suiveur de came est écarté du chemin de came, et une position embrayée dans laquelle le suiveur de came est en appui sur le chemin de came pour produire un couple moteur sur l'arbre des secondes ; ce mécanisme étant remarquable :
• en ce que la came se présente sous forme d'un colimaçon, le chemin de came s'étendant en spirale autour de l'arbre des secondes depuis une extrémité interne jusqu'à une extrémité externe reliées entre elles par une surface de butée qui s'étend sensiblement radialement par rapport à l'arbre des secondes et contre laquelle vient buter le suiveur de came dans une position angulaire de fin de course de l'aiguille trotteuse ;
• en ce qu'il comprend un système à cliquet anti-retour comprenant une roue dentée montée sur l'arbre des secondes, et un cliquet porté par la came et qui attaque la roue dentée.

To achieve all or part of the aforementioned objectives, it is proposed, in the first place, a watch mechanism for resetting the second, which comprises:

• a tree of seconds;
• a second hand running in rotation with the seconds tree;
• a cam integral in rotation with the seconds shaft and a peripheral edge of which forms a cam path;
• a hammer provided with a cam follower, which hammer is rotatably mounted about a hammer axis between a disengaged position in which the cam follower is moved away from the cam path, and an engaged position in which the cam follower is in support on the cam path to produce a motor torque on the seconds shaft; this mechanism being remarkable:
• in that the cam is in the form of a spiral, the cam path spiraling around the seconds shaft from an inner end to an outer end interconnected by an abutment surface which 'extends substantially radially with respect to the seconds shaft and against which abuts the cam follower in an angular end position of the second hand;
• in that it comprises a non-return ratchet system comprising a toothed wheel mounted on the seconds shaft, and a pawl carried by the cam and which drives the toothed wheel.

Thanks to this architecture, the mechanism remains efficient while being quite simple, light and compact. When resetting, the second hand can find a precise position next to a graduation.

• le mécanisme peut comprendre un ressort de marteau pourvu d'une tête fixe et d'une lame élastique qui sollicite le marteau vers sa position embrayée.
• le marteau peut porter un pion primaire en saillie, contre lequel la lame du ressort est en appui permanent.
• le mécanisme peut comprendre un actionneur monté mobile entre une position de retenue dans laquelle il place le marteau dans sa position débrayée, et une position de libération dans laquelle il permet au marteau d'occuper sa position embrayée.
• le marteau peut porter un pion secondaire en saillie, contre lequel un épaulement formé sur l'actionneur est en appui en position de retenue de celui-ci.
• le mécanisme peut comprendre un système à cliquet anti-retour qui n'autorise la rotation de la came que dans un sens.
• le système à cliquet peut comprendre une roue dentée montée de manière coaxiale à l'arbre des secondes, et un cliquet porté par la came et qui attaque la roue dentée.
• l'axe de marteau peut être pourvu d'un excentrique dont la rotation fait débattre le marteau en ajustant la position angulaire de fin de course de l'aiguille trotteuse.

Various additional features may be provided, alone or in combination. For example:

• the mechanism may comprise a hammer spring provided with a fixed head and an elastic blade which urges the hammer towards its engaged position.
• the hammer may carry a projecting primary pin, against which the leaf spring is in permanent support.
• the mechanism may comprise an actuator movably mounted between a retaining position in which it places the hammer in its disengaged position, and a release position in which it allows the hammer to occupy its engaged position.
• the hammer may carry a secondary projection pin, against which a shoulder formed on the actuator is supported in the retaining position thereof.
• the mechanism may comprise a non-return ratchet system which allows rotation of the cam only in one direction.
• the ratchet system may comprise a gear wheel mounted coaxially with the second shaft, and a pawl carried by the cam and engaging the gear wheel.
• the hammer axle may be provided with an eccentric whose rotation causes the hammer to be debated by adjusting the angular end position of the second hand.

It is proposed, secondly, a watch equipped with such a mechanism.

According to a preferred embodiment, the watch may be equipped with a dial provided with a graduation including a twelve-hour index with which the needle is substantially aligned when in angular end position.

Brief description of the figures

• la FIG.1 est une vue en plan d'une montre équipée d'un mécanisme de remise à zéro de la seconde ;
• la FIG.2 est une vue de détail en perspective du mécanisme de remise à zéro de la seconde ;
• la FIG.3 est une vue de détail en coupe du mécanisme de remise à zéro, selon le plan de coupe III-III de la FIG.1 ;
• les FIG.4, FIG.5, FIG.6, FIG.7 et FIG.8 sont des vues de détail en plan, à plus grande échelle, du mécanisme de remise à zéro de la seconde et illustrant diverses phases de son fonctionnement.

Other objects and advantages of the invention will become apparent in the light of the description of an embodiment, given hereinafter with reference to the accompanying drawings, in which:

• the FIG.1 is a plan view of a watch equipped with a reset mechanism of the second;
• the FIG.2 is a detailed perspective view of the reset mechanism of the second;
• the FIG.3 is a sectional detail view of the reset mechanism, according to the sectional plane III-III of the FIG.1 ;
• the FIG.4 , FIG.5 , FIG.6 , FIG.7 and FIG.8 are enlarged plan views of the reset mechanism of the second and illustrate various phases of its operation.

Detailed description of the invention

On the FIG.1 This watch 1 comprises a caseband 2, which may be made of metal (eg steel), or of a synthetic material (eg in a composite material comprising a fiber-filled polymer matrix, typically of carbon).

The watch 1 may include, for wearing on the wrist, a bracelet 3 (in dotted line on the FIG.1 ) which is fixed on the middle part 2 between horns 4 formed projecting thereon.

In the example shown, the middle part 2 is circular in outline, but this form is not limiting. In particular, this contour could be rectangular (eg square).

The middle 2 defines an interior space. The watch 1 comprises, to close this interior space, an ice and a bottom (not shown), fixed on either side of the middle part 2.

The watch 1 is equipped with a dial 6 provided with a scale 7. According to an embodiment illustrated in the drawings, and more particularly on the FIG.1 , the graduation 7 includes indexes 8 for each hour and intermediate indexes 9 for each minute. Intermediate indexes 9 minutes are preferably smaller than the indexes 8 hours.

In the example shown, the hour indexes 8 are not figurative. However, alternatively, the indexes 8 of the hours could be figurative, and be in the form of numbers (eg Roman, Arabic, Gothic, Greek). Be that as it may, the graduation includes a 12-hour index, indicating midnight and noon for hours, and indicating the zero of minutes and seconds.

The watch 1 comprises a watch movement (hereinafter simply called "movement"), which comprises a plate intended to be housed in the middle part 2 being fixed thereto, e.g. by means of screws. Platinum forms a support for various mechanisms such as cog, exhaust, transmission, timer, winding (non exhaustive list).

The movement comprises a timer wheel 11, which includes an hour wheel and a minute wheel (not shown) and a wheel 12 seconds. The mobile 11 timer is rotated about an axis A1.

The mobile 11 timer is rotated by a motor device (not shown). It is preferable that the energy source is a mainspring associated with a balance spring regulator. Nevertheless, that the energy source is a battery associated with a quartz regulator would not be outside the scope of the present invention.

The watch 1 comprises an hour hand and a minute hand (not shown), respectively for displaying the hours and minutes.

• une position rentrée, illustrée en trait plein sur la FIG.1 et dans laquelle la couronne 14 est désaccouplée des aiguilles des heures et des minutes, qui demeurent entraînées en rotation par le mobile 11 de minuterie, et
• une position sortie, illustrée en pointillés sur la FIG.1 et dans laquelle la couronne 14 est accouplée aux aiguilles pour permettre la remise à l'heure.

The watch is equipped with a mechanism 13 of time setting, which includes a winding coupled to the hour and minute hands. This winding includes a crown 14 accessible to the wearer on one side of the middle part 2. The crown 14 is movable between:

• a retracted position, illustrated in solid lines on the FIG.1 and wherein the ring 14 is uncoupled from the hour and minute hands, which remain rotated by the timer wheel 11, and
• an exit position, illustrated in dotted lines on the FIG.1 and wherein the ring 14 is coupled to the needles to allow the time setting.

As illustrated, the watch 1 further comprises a second hand 15 (also called "second hand" or simply "second hand"), coupled to the wheel 12 seconds.

The second hand 12 is rotated, by the mobile 11 timer, about an axis A2 around which it performs a complete revolution in one minute. In the illustrated example, the second hand 15 is a large second hand in the center, its axis A2 of rotation coinciding with the central axis of the dial 6.

The second hand 15 has a distal end 16 which travels, during the rotation of the needle 15, the dial 6 passing successively to the right of each index 8, 9 of the graduation 7.

The second hand 15 is mounted (eg driven) on a second shaft 17 which extends along the axis A2. As we see on the FIG.3 , the shaft 17 seconds comprises an upper section 18, on which is mounted the second needle 15, and a lower section 19.

On the shaft 17 seconds is mounted a pinion 20 which meshes the wheel 12 seconds. More specifically, as illustrated on the FIG.3 , the pinion 20 is mounted on the lower section 19 of the shaft 17 seconds.

As we see on the FIG.3 , and more particularly in the lower left detail medallion, the lower section 19 of the second shaft 17 is provided with one or more larger diameter bead (s) 21 on which the pinion 20 is fitted. This results in a decrease in the interface between the second shaft 17 and the pinion 20.

In this way, the shaft 17 seconds and the pinion 20 are integral in rotation as the shaft 17 seconds is not subjected to any driving torque (or resistant) applied independently of the pinion 20.

Therefore, on the other hand, that a driving torque (or resistant) exceeding a predetermined threshold is applied to the second shaft 17 independently of the pinion 20, the second shaft 17 can rotate freely relative to the pinion 20, which remains fixed because meshing with the 11 timer mobile. In this case, there is a sliding at the interface between the second shaft 17 and the pinion 20.

The watch 1 is equipped with a watchmaking mechanism 22 for resetting the second. By this mechanism 22, the second hand 15 is detached from the mobile 11 timer and reset to the right of the index of twelve hours (that is to say zero) when a time reset is initiated by the wearer, in particular by pulling on the crown 14.

In addition to the seconds shaft 17 and the seconds hand 15 already mentioned, the mechanism 22 for resetting the second comprises a cam 23 integral in rotation with the second shaft 17 and whose peripheral edge forms a path 24 of cam.

According to a preferred embodiment illustrated in the drawings, and in particular on the FIG.3 , the cam 23 is an insert mounted tight (typically by driving) on the shaft 17 seconds.

In the example shown on the FIG.3 , the cam 23 is fitted on the upper section 18 of the shaft 17 seconds. Its height position is fixed by a flange 25 formed on the shaft 17 seconds at the junction between the upper section 18 and the lower section 19, and against which is wedged the cam 23.

As can be seen from the FIG.4 to FIG.8 , the cam 23 is in the form of a spiral: the cam path 24 extends spirally about the axis A2 (that is to say around the shaft 17 seconds) from an end 26 internal (near axis A2), to an outer end 27 (away from the axis A2). The cam path 24 is smooth, without asperity.

The inner end 26 and the outer end 27 are interconnected by an abutment surface 28 which extends substantially radially with respect to the seconds shaft. When seen from the front (that is to say along the axis A2), the contour of the cam 23 is thus similar to the shell contour of a marine cephalopod of the species nautilus.

The cam 23 is advantageously a metal part, e.g. in steel. It is preferably perforated, to be light and to have a low moment of inertia.

• une position débrayée (FIG.4, FIG.8) dans laquelle le suiveur 30 de came est écarté du chemin de came, et
• une position embrayée (FIG.5, FIG.6, FIG.7) dans laquelle le suiveur 30 de came est en appui sur le chemin 24 de came pour produire un couple moteur sur l'arbre 17 des secondes.

The mechanism 22 for resetting the second comprises, moreover, a hammer 29 provided with a follower 30 of cam. This hammer 29 is rotatably mounted around an axis A3 of hammer between:

• a disengaged position ( FIG.4 , FIG.8 ) in which the cam follower 30 is moved away from the cam path, and
• a clutched position ( FIG.5 , FIG.6 , FIG.7 ) in which the cam follower 30 is resting on the cam path 24 to produce a motor torque on the second shaft 17.

The cam follower 30 is eg. in the form of a lug which protrudes at one end 31 free of the hammer, away from the axis A3 hammer. The cam follower 30 is advantageously made of a material with a low coefficient of friction, e.g. in a plastic material (in particular polytetrafluoroethylene, also known under the names PTFE and Teflon®), or in a gemstone (especially ruby). The follower 30 of cam is advantageously fixed rigidly (of releasably) on the hammer 29. Alternatively, the hammer 29 and the cam follower 30 may form a one-piece member, formed from a single machined piece.

In normal operation of the watch 1, the hammer 29 is in its disengaged position. In this case, the second hand 15 is integral with the second shaft 17, pinion 20 meshes the wheel 12 seconds.

When a time reset is initiated by the user, typically by pulling on the ring gear 14, the hammer 29 is moved towards its engaged position to rotate, via the cam follower 30, bearing on the path 24 of FIG. cam, the shaft 17 of the seconds (and with it the second hand 15) - independently of the pinion 20 - to bring the second hand 15 in an angular end position where it is substantially at 12 hour index right (reset).

The angular end position of the second hand (zero position) is determined by the abutment of the cam follower against the abutment surface 28. In this position, illustrated on the FIG.7 (And more particularly in the middle medallion in the middle down), the rotation of the cam 23 (and thus of the second shaft 17 and the seconds hand 15) is stopped.

The support of the cam follower on the cam path 24 is provided by a lever effect exerted on the hammer 29, which tends to rotate it (here clockwise) about the hammer axis A3.

For this purpose, the mechanism 22 comprises a hammer spring 32. This hammer spring 32 is provided with a fixed head 33 and an elastic blade 34 which urges the hammer 29 towards its engaged position.

According to one embodiment, the hammer 29 carries a projecting primary pin 35, against which the blade 34 of the spring is in permanent support. The leverage exerted on the hammer 29 by the elastic blade 34 of the hammer spring 32 via the primary pin 35 is illustrated by the black arrow at the top on the FIG.5 .

The induced rotation of the hammer 29 is indicated by the black arrow in the middle of the FIG.5 . This rotation brings the cam follower 30 into contact with the cam path 24. Since the cam and smooth path 24, and the cam follower 30 has a low coefficient of friction, it can freely slide on the cam path 24.

As the lever effect applied by the hammer spring 32 to the hammer 29 continues, the cam follower 30 slides on the cam surface 24 by exerting on it (and therefore on the cam 23) a non-concomitant force with the cam. A3 axis seconds, which results in a motor torque induced on the cam 23 (and thus on the shaft 17 seconds).

The cam 23, the hammer 29 and the hammer spring 32 are configured so that, irrespective of the angular position of the cam 23, the torque induced thereon by the cam follower 30 is always greater than the threshold beyond of which a sliding occurs at the interface between the shaft 17 seconds and the pinion 20.

As a result, the shaft 17 of the seconds, and with it the second hand 15, is rotated about the axis A2, as illustrated by the black arrow at the bottom right on the FIG.5 the cam follower 30 sliding on the cam surface 24 until it reaches the abutment surface 28, which stops the rotation of the cam 23 (and thus the second hand 15).

• une position de retenue dans laquelle l'actionneur 36 place le marteau 29 dans sa position débrayée (FIG.4, FIG.8), et
• une position de libération dans laquelle l'actionneur 36 permet au marteau 29 d'occuper sa position embrayée (FIG.5, FIG.6, FIG.7).

According to an embodiment illustrated in the drawings, the mechanism 22 for resetting the second comprises an actuator 36 mounted movably between:

• a holding position in which the actuator 36 places the hammer 29 in its disengaged position ( FIG.4 , FIG.8 ), and
• a release position in which the actuator 36 allows the hammer 29 to occupy its engaged position ( FIG.5 , FIG.6 , FIG.7 ).

In the illustrated example, the actuator 36 is in the form of a rod mounted in translation (but it could be mounted in rotation).

The hammer 29 carries a secondary pin 37 protruding against which a shoulder 38 formed on the actuator 36 is supported in position restraint of it. This shoulder 38 is e.g. defined by a claw 39 formed projecting at one end of the actuator 36.

The movement of the actuator 36 is controlled by the crown, and more precisely by the crown 14. Thus, in the retracted position of the crown 14, the latter places the actuator 36 in the retaining position, which maintains the hammer 29 in the disengaged position and allows the rotation of the shaft 17 of seconds (and with it of the second hand 15) induced by the mobile 11 timer.

On the other hand, in the extended position of the crown 14, the latter places the actuator 36 in the release position (horizontal black arrow, top left on the FIG.5 ), which allows the hammer spring 32 to exert its leverage on the hammer 29 to apply the cam follower 30 to the cam path 24.

According to a preferred embodiment illustrated in particular on the FIG.4 , and more particularly in the detail medallion in the lower left, the mechanism 22 for resetting the second comprises a system 40 with a non-return ratchet which only allows the rotation of the cam 23 in one direction (the direction time in the example shown).

The ratchet system 40 comprises a toothed wheel 41 mounted coaxially with the shaft 17 of seconds, and a pawl 42 carried by the cam 23 and which drives the toothed wheel 41.

More precisely, the toothed wheel 41 is rotatably connected to the pinion 20, as the case may be (as illustrated on FIG. FIG.2 ) via a doll 43 driven on the pinion 20. According to one embodiment, the doll 43 is integrated in a transmission wheel 44 meshing eg. a ringing mobile (not shown).

According to a preferred embodiment, the toothed wheel 41 is Breguet type tooth, that is to say that the teeth are triangular and asymmetrical. In the illustrated example, the toothed wheel 41 comprises sixty teeth, which each index, via the pawl 42, a determined position of the seconds hand (which is then called "jumping") corresponding to each of the sixty seconds contained in a minute. In other words, the positions of the second hand are separated from each other by an angle of 6 °.

In the example shown on the FIG.4 , the pawl 42 is biased toward the toothed wheel 41 by means of a spring blade 45 also carried by the cam 23.

The operation of the mechanism 22 for resetting the second is as follows.

In the retracted position of the crown 14, the latter keeps the actuator 36 in the retaining position, which keeps the hammer 29 (and the cam follower 30) in the disengaged position, away from the cam 23.

The shaft 17 of the seconds (and with it the second hand 15) is rotationally fixed to the pinion 20, which, engaged by the mobile 11 timer, drives it in rotation about the axis A2. Under these conditions, the seconds hand 15 acts as a second hand and provides the wearer with an indication of seconds elapsed in the current minute.

In the output position of the ring 14, the latter places the actuator 36 in the release position, which allows the hammer 29 to move, under the effect of lever provided by the hammer spring 32, to its engaged position, wherein the cam follower 30 is in sliding abutment against the cam path 24.

The sliding support of the cam follower 30 against the cam path 24 induced, as explained above, the rotation of the cam 23, and with it the shaft 17 seconds (which slides at its interface with the pinion 20 , which remains fixed in rotation about the axis A2 while remaining meshed by the mobile 11 timer).

The rotation of the cam 23 (in the clockwise direction) and the second hand 15, which is secured thereto, continues until the cam follower 30 comes to bear against the abutment surface 28. which stops the rotation of the cam 23 (and therefore of the second shaft 17 and the second hand 15). The second hand 15 is then in its end position stroke, and is substantially at the right of the index twelve twelve hours on the scale 7 of the dial 6. The pawl 42 is positioned between two successive teeth of the toothed wheel 41, and thus blocks any bounce of the needle when it reaches the end of the race, for the benefit of the accuracy of the reset.

It may be that the second hand 15, at the end of the race, is not exactly at the right of the index twelve twelve hours.

To allow a fine adjustment of the end position of the second hand 15, and to ensure that in this position the second hand 15 is exactly at the right of the twelve hour mark, the axis A3 of hammer is defined by a shaft 46 provided with an eccentric 47.

The rotation of the eccentric 47 causes the hammer 29 to be debated by adjusting the angular end position of the second hand 15 (as suggested by the various positions outlined in dotted line on the FIG.8 ).

The rotation of eccentric 47 is e.g. performed by a manual action, typically by means of a screwdriver. For this purpose, as illustrated in particular on the FIG.7 an end of the eccentric 47 is shaped as a recess 48 (eg a slot) for a screwdriver. We have illustrated, in the detail medallion at the bottom left on the FIG.7 , the rotation of the eccentric (double black arrow), and its effect (in dotted lines) on the positioning of the hammer 29.

As soon as the ring gear 14 is returned to its retracted position, the actuator 37 is returned to its retaining position ( FIG.8 ). The displacement of the actuator 37 exerts traction on the secondary pin 37 and rotates the hammer 29 against the return force of the spring 32. The rotation of the hammer slides the cam follower 30 along the abutment surface 28, and then escape the cam follower 30 from the cam 23. Therefore, no driving or resistant torque no longer applies to the second shaft 17, whose frictional forces at the interface between the (s) bead (s) 21 and the pinion 20 re-couples it in rotation to it.

As a result, the rotation of the pinion 20, engaged by the mobile 11 timer (and more precisely by the wheel 12 seconds) rotates the shaft 17 seconds, and with it the second hand 15 seconds in the movement ordinary cyclic.

The mechanism 22 for resetting seconds that has just been described has the following advantages.

First, in comparison with known heart mechanisms, the present mechanism 22 is of simpler architecture. The hammer 29, in particular, is of less complex shape. The absence of heel, and the presence of the cam follower 30 which, at the end of the stroke, merely abuts against the abutment surface 28, avoids the rebounds of the second hand 15, in favor of the reliability of the mechanism 22 .

As already mentioned, the rebounds are also prevented by the ratchet system 40, which provides unidirectional rotation of the second hand during its reset.

Being simpler, this mechanism 22 is lightweight, compact, and easy to manufacture.

This results in particular greater reliability, and therefore a longer life of the mechanism 22 (and therefore the watch 1).

Claims (10)

Mechanism (22) watchmaker reset of the second, which comprises: - A tree (17) seconds; - A hand (15) second hand rotating in the shaft (17) seconds; - A cam (23) integral in rotation with the shaft (17) seconds and a peripheral edge forms a cam path (24); - A hammer (29) provided with a follower (30) cam, the hammer (29) being rotatably mounted about a hammer axis (A3) between a disengaged position in which the cam follower (30) is spaced apart from the cam path (24), and an engaged position in which the cam follower (30) bears on the cam path (24) to produce a driving torque on the seconds shaft (17); this mechanism (22) being characterized : - in that the cam (23) is in the form of a spiral, the cam path (24) extending spirally around the shaft (17) seconds from an end (26) internal up an outer end (27) interconnected by an abutment surface (28) which extends substantially radially with respect to the second shaft (17) and against which the cam follower (30) abuts in an angular position end-of-stroke needle (15) second hand; - in that it comprises a non-return ratchet system comprising a toothed wheel (41) mounted on the shaft (17) seconds, and a pawl (42) carried by the cam and which attacks the wheel (41) toothed. Mechanism (22) according to claim 1, characterized in that it comprises a hammer spring (32) provided with a fixed head (33) and an elastic blade (34) which urges the hammer (32) towards its engaged position. Mechanism (22) according to claim 2, characterized in that the hammer (29) carries a projecting pin (35) projecting against which the blade (34) of the spring is in permanent support. Mechanism (22) according to claim 2 or claim 3, characterized in that it comprises an actuator (36) movably mounted between a retaining position in which it places the hammer (29) in its disengaged position, and a position of release in which it allows the hammer (29) to occupy its engaged position. Mechanism (22) according to claim 4, characterized in that the hammer (29) carries a pin (37) projecting secondary, against which a shoulder (38) formed on the actuator (36) is supported in the retaining position of it. Mechanism (22) according to one of the preceding claims, characterized in that the toothed wheel (41) comprises a Breguet type toothing. Mechanism (22) according to claim 6, characterized in that the toothed wheel (41) comprises sixty teeth. Mechanism (22) according to one of the preceding claims, characterized in that the axis (A3) hammer is formed by a shaft (46) provided with an eccentric (47) whose rotation causes the hammer to debate (29) by adjusting the angular end position of the second hand (15). Watch (1) equipped with a clock-setting mechanism (22) for resetting the second according to one of the preceding claims. Watch (1) according to claim 9, equipped with a dial (6) provided with a graduation (7) including a index (10) of twelve hours with which the second hand (15) is substantially aligned when it is in angular end position.

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