CH714357A2 - Watchmaking mechanism for resetting the second spiral cam. - Google Patents

Abstract

The invention relates to a watchmaking mechanism (22) for resetting the second, which comprises: a seconds tree; A needle (15) second hand; A cam (23) forming a spiral cam path (24) which spirals around the seconds shaft from an inner end to an outer end interconnected by a radial abutment surface (28) ; 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 spaced 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 drives the toothed wheel (41).

Description

Description

Technical Field [0001] 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.

BACKGROUND ART [0002] A mechanism for resetting the second can be found: in most chronograph watches, and in some watches provided with a second-hand hand (also called a second hand, or more simply second hand) and whose setting of the time is accompanied by an automatic reset of the second hand.

Conventionally, such a mechanism comprises (besides the second hand and its seconds shaft): - a cam integral in rotation with the second shaft and a peripheral edge forms a cam path; a hammer carrying a cam follower, said hammer being rotatably mounted around 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 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 C.-A. Reymondin et al., "Theorie d'horlogerie", Federation of Technical Schools, 2015 edition, p. 238.

In chronographs, the hammer is a complex piece provided with several cam followers that simultaneously hit several respective cams, integral with the hour hand, the minute hand, the seconds hand (and , more occasionally, a tenths needle).

In the automatic reset watches of the second hand, as described in European Patent EP 2,224,294 (Glasshütte) the hammer is simpler form but the principle is the same.

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

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

[0009] First, the position of the second hand during the reset is, most often, 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 heart, the hammer rubs on it by a sharp edge, as shown in Fig.11.29 of the aforementioned manual, which increases the stress concentration, wear and mechanical fatigue of these rooms.

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 shaft, but remains, before coming to a stop, animated by damped oscillations which impede the perception of precision expected by an informed user.

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

A first objective is to provide a reset mechanism of 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 having greater reliability, and therefore a greater longevity.

A third objective is to propose a reset mechanism of the second architecture simpler (and therefore less cumbersome, lighter and easier to manufacture) than the known mechanisms. SUMMARY OF THE INVENTION [0017] In order to achieve all or part of the aforementioned objectives, it is proposed, in the first place, a clocking mechanism for resetting the second, which comprises: a seconds tree; - a second hand running in rotation of the seconds shaft; 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, said hammer being 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 follower cam is pressing on the cam path to produce a motor torque on the seconds shaft; this mechanism is remarkable: - in that the cam is in the form of a spiral, the cam path extending in a spiral 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.

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

Various additional features may be provided, alone or in combination. Thus, 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 of the 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 only allows the rotation of the cam in one direction; the ratchet system may comprise a toothed wheel mounted coaxially with the seconds shaft, and a pawl carried by the cam and which engages the toothed wheel; - The hammer axis can be provided with an eccentric whose rotation causes the hammer to debate 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 position end of stroke.

BRIEF DESCRIPTION OF THE FIGURES [0022] 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: FIG. 1 is a plan view of a watch equipped with a reset mechanism of the second; fig. 2 is a perspective detail view of the resetting mechanism of the terminal; fig. 3 is a detailed sectional view of the reset mechanism, along the section plane III-III of FIG. 1; figs. 4, fig. 5, fig. 6, fig. 7 and fig. 8 are detailed plan views, on a larger scale, of the reset mechanism of the second and illustrating various phases of its operation.

Detailed Description of the Invention [0023] In FIG. 1 shows a watch 1. This watch 1 comprises a caseband 2, which may be made of metal (eg steel), or of a synthetic material (for example in a composite material comprising a polymer matrix loaded with fibers, typically carbon).

The watch 1 may include, for wearing on the wrist, a bracelet 3 (in dotted line in Figure 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 part 2 defines an interior space 5. 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 in 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 indexes 8 hours 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 mobile 11 timer, which includes a wheel hours 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 the display of hours and minutes.

The watch is equipped with a mechanism 13 of time, which includes a winding coupled to the hour and minute hands. This winding includes a ring 14 accessible to the wearer on one side of the middle part 2. The ring 14 is movable between: - a retracted position, shown in solid lines in FIG. 1 and wherein the ring 14 is uncoupled from the hour and minute hands, which remain rotated by the motive wheel 11, and - an extended position, shown in dashed lines in 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 needle" or simply "second hand"), coupled to the wheel 12 seconds.

The seconds hand 12 is rotated by the mobile 11 timer around 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 being driven) on a second shaft 17 which extends along the axis A2. As seen in fig. 3, the shaft 17 of the seconds comprises an upper section 18, on which the second hand 15 is mounted, and a lower section 19.

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

As seen in 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 bead (s) 21 of larger diameter, 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 subject to any driving torque (or resistant) applied independently of the pinion 20.

Therefore, in contrast, a motor torque (or resistant) exceeding a predetermined threshold is applied to the second shaft 17 independently of the pinion 20, the shaft 17 seconds 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 watch 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 second shaft 17 and the second needle 15 already mentioned, the mechanism 22 for resetting the second comprises a cam 23 integral in rotation with the shaft 17 seconds and a peripheral edge form a cam path 24.

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

In the example illustrated in FIG. 3, the cam 23 is fitted on the upper section 18 of the shaft 17 seconds. Its height position is fixed by a collar 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 in FIGS. 4 to fig. 8, the cam 23 is in the form of a spiral: the cam path 24 extends in a spiral around the axis A2 (that is to say around the shaft 17 seconds) from one end 26 (near the A2 axis), 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 a stop 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 preferably a metal part, e.g. in steel. It is preferably perforated, to be light and to have a low moment of inertia.

The mechanism 22 for resetting the second comprises, moreover, a hammer 29 provided with a cam follower 30. This hammer 29 is rotatably mounted around a hammer axle A3 between: a disengaged position (FIG 4, FIG 8) in which the cam follower 30 is spaced from the cam path, and a clutched position (FIG. Fig. 5, Fig. 6, Fig. 7) in which the cam follower 30 bears on the cam path 24 to produce a driving torque on the second shaft 17.

The cam follower 30 is for example. 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 cam follower 30 is advantageously fixed rigidly (releasably) on the hammer 29. Alternatively, the hammer 29 and 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 14, the hammer 29 is moved to its engaged position to rotate, via the follower 30 of cam pressing on the cam path 24, the shaft 17 seconds (and with it the second hand 15) - this independently of the pinion 20 - to bring the second hand 15 in an angular position of end of race where it is is substantially at the right of the index of twelve twelve hours (reset).

The angular end position of the second hand 15 (position zero) is determined by the abutment of the cam follower 30 against the abutment surface 28. In this position, illustrated in FIG. 7 (and more particularly in the medallion of detail in the middle down), the rotation of the cam 23 (and therefore of the second shaft 17 and the second hand 15) is stopped.

The support of the cam follower 30 on the cam path 24 is provided by a lever effect exerted on the hammer 29, which tends to rotate it (here in a clockwise direction) about the axis A3 of the cam. hammer.

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 resilient blade 34 of the hammer spring 32 via the primary pin 35 is illustrated by the black arrow at the top in FIG. 5.

The induced rotation of the hammer 29 is indicated by the black arrow in the middle of 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.

The lever effect applied by the hammer spring 32 on the hammer 29 continuing, the cam follower 30 slides on the cam surface 24 by exerting on it (and thus on the cam 23) a non-concurrent effort with the axis A3 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 spring 32 hammer are configured so that, regardless of the angular position of the cam 23, the torque induced on it by the cam follower 30 is always greater than the threshold beyond which there is a sliding at the interface between the second shaft 17 and the pinion 20.

It follows that the shaft 17 seconds, and with it the second hand 15, is rotated about the axis A2, as shown by the black arrow in the lower right in FIG. 5, the cam follower 30 sliding on the cam surface 24 until it reaches the abutment surface 28, thereby stopping the rotation of the cam 23 (and thus the second hand 15).

According to an embodiment illustrated in the drawings, the mechanism 22 for resetting the second comprises an actuator 36 mounted movably between: - a retaining 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 example shown, the actuator 36 is in the form of a rod mounted in translation (but it could be mounted in rotation).

The hammer 29 carries meanwhile a secondary pin 37 protruding against which a shoulder 38 formed on the actuator 36 is supported in the retaining position thereof. 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 winder, and more precisely by the ring 14. Thus, in the retracted position of the crown 14, it 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 seconds (and with him the second hand 15) induced by the mobile 11 timer.

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

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

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

More specifically, the toothed wheel 41 is rotatably connected to the pinion 20, as the case may be (as illustrated in 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 e.g. a ringing mobile (not shown).

According to a preferred embodiment, the gear wheel 41 is toothed Breguet type, 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 one minute. In other words, the positions of the second hand are separated from each other by an angle of 6 °.

In the example illustrated in 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 of resetting the second is as follows.

In the retracted position of the ring 14, it 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 second shaft 17 (and with it the seconds hand 15) is rotationally fixed to the pinion 20, which, meshing with the mobile 11 timer, causes it to rotate 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 spring 32 hammer, to its engaged position, in which the cam follower 30 is slidingly abutting against the cam path 24.

The sliding support of the cam follower 30 against the induced cam path 24, 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 of the seconds hand 15, which is secured to it, continues until the cam follower 30 comes to bear against the surface 28 of FIG. abutment, which stops the rotation of the cam 23 (and therefore of the shaft 17 seconds and 15 seconds needle). The seconds hand 15 is then in its end-of-travel position, and is located substantially at the right of the twelve hour markers on the graduation 7 of the dial 6. The pawl 42 is positioned between two successive teeth of the gear wheel 41, and thus blocks any bounce of the needle when it reaches the end of the race, to 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 ensure that in this position the second hand 15 is exactly the right of the index of twelve hours, the Axis A3 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 dotted positions in FIG 8).

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

When 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 biasing force of the spring 32. The rotation of the hammer slides the cam follower 30 along the surface 28 of stop, then escape the cam follower 30 of the cam 23. Therefore, no motor or resistant torque no longer applies to the shaft 17 seconds, whose friction forces at the interface between the (s) ) bead (s) 21 and the pinion 20 re-couples in rotation to it.

It follows that the rotation of the pinion 20, meshing with the mobile 11 timer (and more precisely by the wheel 12 seconds) rotates the shaft 17 seconds, and with him the second hand 15 seconds in the ordinary cyclical movement.

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

First, in comparison with known core 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 ensures the unidirectional character of the rotation of the second hand 15 when it is 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)

claims 1. Mechanism (22) watchmaker reset the second, which comprises: - A shaft (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 in a spiral around the shaft (17) of the seconds since a end (26) internal to an end (27) external interconnected by a surface (28) abutment which extends substantially radially relative to the shaft (17) seconds against which abuts the follower ( 30) in an angular end position of the second hand (15); - 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. 2. Mechanism (22) according to claim 1, characterized in that it comprises a spring (32) hammer provided with a head (33) fixed and a blade (34) elastic which solicits the hammer (32) towards its engaged position. 3. 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. 4. 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 release position in which it allows the hammer (29) to occupy its engaged position. 5. Mechanism (22) according to claim 4, characterized in that the hammer (29) carries a secondary pin (37) projecting against which a shoulder (38) formed on the actuator (36) bears in position restraint of it. 6. Mechanism (22) according to one of the preceding claims, characterized in that the toothed wheel (41) comprises a Breguet type toothing. 7. Mechanism (22) according to claim 6, characterized in that the toothed wheel (41) comprises sixty teeth. 8. 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 makes the hammer debate ( 29) by adjusting the angular end position of the second hand (15). 9. Watch (1) equipped with a mechanism (22) clocking the reset of the second according to one of the preceding claims. 10. 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 needle (15) seconds is substantially aligned when it is in angular end position.