HK1205799B - Zero-reset device with independent hammers - Google Patents

Description

Zero-resetting device with independent ram

Technical Field

The invention relates to a zero-reset device for a timepiece, in particular for a chronograph timepiece, comprising a first control device, a second control device kinematically connected to the first control device, at least two zero-reset cams, and at least two respective zero-reset hammers pivoting independently of each other and actuatable to cooperate with the respective zero-reset cams.

The invention relates more particularly to a timepiece, in particular a chronograph timepiece, having a mechanical movement and fitted with a chronograph mechanism or flyback hands. In this context, it is conventional that each of the seconds, minutes and hours hands, possibly arranged as flyback hands, is mounted on a shaft fitted with a heart-shaped cam which can cooperate with a respective hammer to return the hands to their rest position in the case of zero reset or to the position defined by the reference hand in the case of a flyback hand mechanism. In conventional mechanisms, the ram is often disposed on a single piece portion. The above arrangement in conventional mechanisms can cause several problems due to the increase in the force exerted by such a portion, the necessary synchronization when hitting on the various hearts, the production precision, the bulk of such a portion and other drawbacks.

Background

It has therefore been proposed herein to use an arrangement of independent rams. For example, patent application EP 2241945 proposes a chronograph mechanism having a second hammer and a minute hammer which pivot independently of each other and are connected by a connecting element. If the arrangement proposed has a spring acting independently on the ram, it is necessary anyway, in particular due to the connecting element, to provide coaxial pivoting of the ram and of the sub-counter pawl, which pivots angularly concentrically with the sub-counter wheel, which considerably limits the use of such a device. Another design has been proposed in document EP 1890205. The respective device comprises a plurality of rams which can be actuated by the control element so as to cooperate with the respective hearts. Ram hammer

Pivoting about respective independent pivots and hinged to said control element, so that the translational movement of said control element, thanks to its kinematic connection to the ram, directly causes cooperation between the ram and the respective heart. However, such a direct kinematic connection is not optimal. In addition, this means that the mechanism has no springs, which tend to apply the ram against the heart; and the potential lack of precision must also be compensated by making the arms of the ram elastic. It should therefore be noted that the solutions of the prior art currently known are not entirely satisfactory and/or cannot be used by all types of chronograph mechanism.

Disclosure of Invention

It is therefore an object of the present invention to at least partly overcome the drawbacks of the known devices and to produce a zero-reset device equipped with independent rams, which has improved operational reliability, high precision in the simultaneous actuation of the rams and also a well-defined force applied to the heart-shaped cam. A further object of the invention is also to produce such a device by means of a robust construction, which is as compact as possible and which is simple and reliable during use. The device should be suitable for implementation as well as in the chronograph mechanism itself, as in any other similar application, such as a flyback hand mechanism.

To this end, the invention proposes a zero-reset device of the type described above. Specifically, the apparatus according to the invention comprises: at least two ram springs, each capable of applying a pretension that pivots the zero-reset ram in the direction of the corresponding zero-reset cam; and a winding and releasing device; and a locking device which is able to wind the hammer springs during a first phase of actuation of the first control device and which also cooperates with the locking device during a second phase of actuation of the first control device, so that the locking device is transferred from a first rest position, in which it holds the zero-reset hammers in their rest position, to a second release position, in which it releases the zero-reset hammers, which come in each case under the action of the respective hammer spring into their position cooperating with the respective zero-reset cam.

As a result of these measures, the zero reset is only performed when the manual force exerted by the user of the timepiece on the first control exceeds a predetermined threshold. In addition, the force applied to the cam by the hammer is always the same and equal to a predetermined value. This is achieved while ensuring maximum independence of the rams which have no direct kinematic connection between them, at least during their application to the cam.

These advantages may also be enhanced by the advantageous arrangement of the winding and release means and the locking means. Also, the device comprises return means of the zero-return ram, which return means are capable of returning said ram to its rest position after its actuation, such return means being capable of being arranged to maintain independence between the rams in an optimal manner. In addition, the zero-reset rams of the device according to the invention may advantageously all have the same geometry. All these factors contribute to a particularly simple and reliable implementation of such a device.

Further features and corresponding advantages will be apparent from the detailed description, which follows, which presents the invention in more detail.

Drawings

The figures schematically show embodiments of the invention by way of illustration.

Figure 1a shows a schematic perspective view of a first embodiment of a zero reset device according to the present invention; fig. 1b and 1c show a plan view of this device and a longitudinal section of this device along the line I-I indicated in fig. 1b, respectively.

Fig. 2a shows a plan view of the zero reset device according to fig. 1a to 1c in its position just after the start of the first phase of actuation of the first control device; figure 2b is a plan view of the device in its position during the first phase of said actuation at the instant in which the winding and release means establish contact with the locking means; FIG. 2c is a plan view of the device in its position at the end of the first stage of actuation, just prior to the instant at which the winding and release device causes the release of the zero reset ram; FIG. 2d is a plan view of the device in its position during the second phase of actuation in which the zero reset ram has impacted the corresponding zero reset cam; fig. 2e is a plan view of the device in its position, the first control means having been released by the user so that the zero reset ram and the locking means have returned to their rest positions.

Figure 3a shows a schematic perspective view of a second embodiment of a zero reset device according to the present invention; fig. 3b and 3c show a plan view of this device and a longitudinal section of this device along the line I-I indicated in fig. 3b, respectively.

Fig. 4a shows a plan view of the zero reset device according to fig. 3a to 3c in its position just after the start of the first phase of actuation of the first control device; figure 4b is a plan view of the device in its position during the first phase of said actuation, at the instant in which the winding and release means establish contact with the locking means; FIG. 4c is a plan view of the device in its position at the end of the first stage of actuation, just prior to the instant at which the winding and release device causes the release of the zero reset ram; FIG. 4d is a plan view of the device in its position during the second phase of actuation in which the zero reset ram has impacted the corresponding zero reset cam; fig. 4e is a plan view of the device in its position, the first control means having been released by the user so that the zero reset ram and the locking means have returned to their rest positions.

Detailed Description

The invention will now be described in detail with reference to the accompanying drawings, which show by way of illustration embodiments of the invention.

The present invention relates to a zero reset device intended to be integrated in a timepiece, preferably a watch with mechanical movement. For the sake of simplicity of language, in the following, reference will be made synonymously to "timepiece" and "watch", without thereby limiting the scope of the respective interpretations, which apply in any case to any type of timepiece having either a mechanical energy source or an electrical energy source. In addition, such a timepiece usually comprises a chronograph mechanism or a flyback hand mechanism intended to be equipped with a zero reset device according to the invention. The following description will be limited to the structure and function of the device in the sense that the timing and flyback hands mechanisms and also other similar mechanisms suitable for integration with the device according to the invention are known to the person skilled in the art.

In order to first explain the structure and the elements of the zero reset device according to the present invention, reference is made to fig. 1a to 1c, which schematically show by way of example a first embodiment of such a device by means of a schematic perspective view, a plan view, and a longitudinal section of such a device along the line I-I of fig. 1b, respectively, of such a device. It can be seen that this device, like the one of the prior art, comprises a first control device 1, a second control device 2, at least two zero-reset cams 3.1, 3.2, 3.3, and at least two respective zero-reset rams 4.1, 4.2, 4.3, this second control device 2 being kinematically connected to said first control device 1. The rams 4.1, 4.2, 4.3 pivot independently of one another about pivots 4.1.1, 4.2.1, 4.3.1 and can be actuated so as to cooperate with the respective zero-reset cams 3.1, 3.2, 3.3, these pivots 4.1.1, 4.2.1, 4.3.1 generally being positioned differently with respect to one another. To this end, each of said hammers has an arm 4.1.3, 4.2.3, 4.3.3, in these arms 4.1.3, 4.2.3, 4.3.3 the free end comprises a surface, preferably a plane surface, which forms the hammer itself and can be pressed against the respective zero-reset cam 3.1, 3.2, 3.3. These cams 3.1, 3.2, 3.3 are generally heart-shaped, preferably in the shape of an asymmetrical heart, so as to obtain an improved performance of the hammer-heart assembly, and are mounted on the axis of rotation of the respective indicating element, often a pointer or a disc, or on the axis of a wheel, which is connected kinematically, directly or indirectly, to the axis of rotation of this element. For example, the indicator element may be the second, minute and hour hands of a chronograph mechanism or of a corresponding flyback hand mechanism, so that the three rams 4.1, 4.2, 4.3 or the three hearts 3.1, 3.2, 3.3 shown in the figures correspond to the rams or hearts of hour, minute and second. The first control device 1 can move in translation and the second control device 2 can move in rotation about a pivot 2.1, a control return spring (not shown in the figures) tending to bear against one of the rams, preferably against the first ram 4.1, applying the end of the second control device 2, as shown in fig. 1a and 1 b. Usually, the first control means 1 is realized by a push-button to which a user of the timepiece can apply a manual force in order to cause pivoting of this second control means 2 by means of said kinematic connection between the first control means 1 and the second control means 2. After the manual force is exerted on the first control device 1 by the user, the winding stop 6.8, which is visible, for example, in fig. 1b and 3b, limits the course of the second control device 2 in the direction away from the striker 4.1, 4.2, 4.3. The first control device 1 thus allows the control of a respective function, for example the zero reset of the hands of a chronograph mechanism or a flyback hands mechanism, by means of the second control device 2.

Unlike the prior art devices, the present device comprises: at least two ram springs 5.1, 5.2, 5.3, each capable of exerting a pretension that pivots one of the zero-reset rams 4.1, 4.2, 4.3 in the direction of the respective zero-reset cam 3.1, 3.2, 3.3; and a winding and releasing device 6; and a locking device 7. In a first embodiment of the device shown in fig. 1a to 1c, the hammer springs are formed by leaf springs, of which one end is rigidly mounted on the respective hammer and of which the other end is free, so as to be able to receive a winding force by means of the winding and release device 6, as will become clearer from the following description. As can be clearly seen, each spring can be mounted on said winding and releasing device 6 and its free end can cooperate with a striker 4.1, 4.2, 4.3, which design is not shown in the figures.

In fact, said winding and releasing means 6 are able to wind said striker springs 5.1, 5.2, 5.3 during a first phase of actuation of the first control device 1 and also cooperate with said locking means 7 during a second phase of actuation of the first control device 1, so that said locking means 7 are transferred from a first rest position, in which the locking means 7 hold the zero-return striker 4.1, 4.2, 4.3 in its rest position, to a second release position. In this second release position, the locking device 7 releases the zero reset rams 4.1, 4.2, 4.3, which zero reset rams 4.1, 4.2, 4.3 come in each case under the action of the respective ram springs 5.1, 5.2, 5.3 into their position of cooperation with the respective zero reset cams 3.1, 3.2, 3.3, as will be described in more detail in the following description.

A first embodiment of the device according to the invention is clearly shown in fig. 1a and 1b, the winding and releasing means 6 being formed by a bar kinematically connected to the second control means 2 and comprising at least two (three in the example shown in the figures) winding elements 6.1, 6.2, 6.3, each of these winding elements 6.1, 6.2, 6.3 being able to bear against a free end of a respective hammer spring 5.1, 5.2, 5.3, so as to be able to wind said hammer spring 5.1, 5.2, 5.3 during said first phase of actuation of the first control means 1. The winding element can preferably be formed by winding pins 6.1, 6.2, 6.3, which winding pins 6.1, 6.2, 6.3 are mounted at suitable distances along the bar 6.

The winding and release device 6 also comprises a release portion 6.4, which release portion 6.4 is able to cooperate with the locking device 7, so that said locking device, during said second phase of actuation of the first control device 1, is transferred from its first rest position, in which the locking device 7 holds the zero-reset striker 4.1, 4.2, 4.3 in its rest position, to its second release position, in which the locking device 7 releases the zero-reset striker 4.1, 4.2, 4.3. This release portion is preferably formed by an inclined plane or rounded edge 6.4 arranged close to its end, which inclined plane or rounded edge 6.4 is oriented towards said locking means 7 and can be brought into contact with said locking means 7.

Similarly to the second control device 2, which is usually articulated at one of its ends to the first control device 1, the kinematic connection between the winding and release device 6 and the second control device 2 can be produced, for example, by a pivot pin 6.7, which pivot pin 6.7 is articulated to the other end 2.2 of the second control device 2. Also in its end opposite to the second control means 2, a longitudinal groove 6.5 is present (in which longitudinal groove 6.5 is fitted a guide shaft 6.6, which guide shaft 6.6 is mounted on the bridge of the corresponding timepiece and is visible in fig. 3b by way of example), said winding and release means 6 being able to move in rotation around said guide shaft 6.6 following the actuation of the first control means 1. The rotational movement preferably has a large radius.

As regards said locking means 7, it is preferably formed by a locking lever which is mounted pivotably about a pivot 7.1 and is prestressed by a return locking spring in the direction of one of the respective zero-return rams 4.1, 4.2, 4.3 against a locking stop 7.3, which locking stop 7.3 defines the rest position of said locking means. The locking device is preferably prestressed in the direction of the first zero reset striker 4.1, which first zero reset striker 4.1 is arranged closest to the second control device 2, however, it is possible that the locking device is prestressed in the direction of one of the other striker 4.2, 4.3. The ram against which the locking lever 7 is prestressed, thus typically the first zero reset ram 4.1, also as shown in the figures, comprises a recess 4.1.4 into which a locking portion 7.2 of the locking lever 7 can be engaged or disengaged from this recess 4.1.4. In addition, at least this striker preferably also comprises a guide portion 4.1.5, which guide portion 4.1.5 may be slightly rounded, allowing the locking portion 7.2 to be guided during its movement after disengagement, and then subsequently in its return movement towards the notch 4.1.4. The locking portion may be realized by a locking pin 7.2 mounted on the lever 7 or by a suitably shaped one-piece portion intended to engage said recess 4.1.4 in one of the zero-return rams 4.1, 4.2, 4.3.

As can also be seen from fig. 1a to 1c, the zero-reset device according to the invention comprises a return device 8 of the zero-reset rams 4.1, 4.2, 4.3, which return device is capable of returning the zero-reset rams 4.1, 4.2, 4.3 into their rest position after actuation thereof. In the first embodiment, schematically illustrated in fig. 1a to 1c, the return means 8 are formed by a return bar kinematically connected to each of the zero-reset rams 4.1, 4.2, 4.3. In order to ensure that each hammer 4.1, 4.2, 4.3 can independently strike the respective heart 3.1, 3.2, 3.3, the connection between the return bar 8 and the hammer is produced virtually without play with respect to one of the zero-reset hammers 4.1 (and thus with respect to the first hammer 4.1 cooperating with the locking device 7 in the embodiment shown in the figures) and virtually with play with respect to the other zero-reset hammers 4.2, 4.3. This can be implemented as follows: the first pivot 8.1 is placed practically without play between the first striker 4.1 and the return bar 8, while the second 8.2 and third 8.3 pivots, mounted respectively on the second 4.2 and third 4.3 striker, fit with play in the respective openings of the return bar, the respective dimensions of which are greater than the diameter of the pivots 8.2, 8.3, as can be seen in fig. 1 b. This play is preferably approximately from 0.10mm to 0.35mm, the openings being additionally arranged such that: the edges of the opening do not touch the second pivot 8.2 and the third pivot 8.3 when the ram is pressed against the respective heart. The return stop 8.4 defines the rest position of the return device 8 of the zero-reset rams 4.1, 4.2, 4.3 respectively, by being positioned such that one of the rams (the third ram 4.3 in the example shown) bears against said return stop 8.4 as soon as the user no longer applies a manual force to the first control device 1. In this case, in fact, said control return spring of the second control device 2 returns said second control device and the zero-return rams 4.1, 4.2, 4.3 into their respective rest positions by means of the return device 8.

The above explanations relating to the structure and elements of the zero reset device according to the present invention also allow to easily understand the function of said device, in particular with the aid of fig. 2a to 2 e. In fact, in the rest position shown in fig. 1b, the hammer springs 5.1, 5.2, 5.3 are not wound and the locking device 7 bears against the locking stop 7.3 in its rest position. Similarly, in the example shown in the figures, the control return spring forces the end 2.2 of the second control device 2 against the first striker 4.1. This first ram 4.1 pushes the return bar 8 in the direction of the second 4.2 and third 4.3 rams so that the return bar holds the rams 4.1, 4.2, 4.3 in a position away from the heart, the return stop 8.4 defining the distance of the rams 4.1, 4.2, 4.3 from the respective heart 3.1, 3.2, 3.3. In this rest position, also the small play in the rotation with the second 4.2 and third 4.3 striker will be noted, provided that the second 8.2 and third 8.3 pivots mounted on these striker are free in their respective fits on the return bar 8, while the first 4.1 striker has no play. In other words, in the rest position, all the rams 4.1, 4.2, 4.3 are clear of the hearts 3.1, 3.2, 3.3 and are held in this position by the control return spring by means of the return bar 8.

Fig. 2a shows a plan view of the zero reset device according to fig. 1a to 1c in its position just after the start of the first phase of actuation of the first control device 1 after the application of manual force by the user of the respective timepiece, and thus shows the step of the device just leaving the rest position. By pressing on the push button 1, the user pivots the second control means 2 and also the winding and release means 6. This winding and releasing device 6 is used in this actuation phase to wind the striker spring 5.1, 5.2, 5.3 by means of the winding pins 6.1, 6.2, 6.3, which winding pins 6.1, 6.2, 6.3 are carried by said winding and releasing device. By comparing fig. 1b and 2a, it is noted that before the winding of the spring begins, that is to say before each of the winding pins 6.1, 6.2, 6.3 reaches the free end of the respective striker spring 5.1, 5.2, 5.3, a small amount of play is first to be compensated, preferably approximately from 0.10mm to 0.40 mm. In this position, there is no longer any contact between the free end of the second control device 2 and the first ram 4.1. Similarly, it is noted that the locking pin 7.2, in the position shown in fig. 2a, is only in contact with the first zero return striker 4.1 at its notch 4.1.4, while this contact has not yet been established in the rest position shown in fig. 1 b.

Fig. 2b is a plan view of the device in its position during the first stage of said actuation at the instant when the winding and release means 6 are in contact with the locking means 7 when the pressure by the user on the push button 1 continues, and therefore at the instant when the winding and release means 6 is no longer used only to wind the striker spring 5.1, 5.2, 5.3, but it also performs the release function. In fact, during this phase, the first striker 4.1 is incrementally stressed by its spring 5.1, which spring 5.1 is in turn incrementally wound by the winding pin 6.1, while the rest is limited in rotation by the locking pin 7.2 (the locking pin 7.2 is mounted on the locking device 7). The springs 5.2, 5.3 of the second 4.2 and third 4.3 rams wind up themselves simultaneously, provided that these rams 4.2, 4.3 cannot hit their respective heart 3.2, 3.3, because the return bar 8 keeps them at a distance, which return bar 8 is blocked by means of the first ram 4.1. On the other hand, contact is made between the release portion 6.4 of the winding and release device 6, that is to say the inclined plane or rounded edge 6.4, and the locking device 7, which gradually causes pivoting of the locking device 7. The locking pin 7.2, which locking pin 7.2 is mounted on the locking device, thus slides along it before disengaging from the recess 4.1.4 in the striker 4.1.

Fig. 2c is a plan view of the device in its position at the end of the first phase of said actuation, just before the instant in which the winding and releasing device 6 causes the release of the zero-reset ram (with which the winding and releasing device 6 cooperates) by means of the locking device 7. In particular, fig. 2c shows the position corresponding to the maximum winding of the hammer springs 5.1, 5.2, 5.3 and just before the release of the hammers 4.1, 4.2, 4.3, that is to say at the instant before the locking pin 7.2 (which locking pin 7.2 is mounted on the locking device 7) disengages from the recess 4.1.4 in the first hammer 4.1. The instant of release corresponds to the following instants: the locking pin 7.2 can no longer hold the first striker 4.1 and then slide along said guide portion 4.1.5 of the first striker 4.1, no longer opposing the movement of this striker 4.1 except for the negligible friction force generated by the action of the return spring of the locking device 7, which causes the locking pin 7.2 to be applied against this guide portion 4.1.5 of the first striker 4.1.

Fig. 2d is a plan view of the device in its position during the second phase of actuation, when the pressure by the user on the push button 1 continues, the zero reset rams 4.1, 4.2, 4.3 having impinged on the respective zero reset cams 3.1, 3.2, 3.3. In fact, the first striker 4.1 is released at the end of the actuation phase shown in fig. 2c, the return bar 8 being also movable due to the fact that it is connected to the first striker 4.1. Since the return bar is the only part holding the second 4.2 and third 4.3 rams, the two rams are also released. At the moment of release, the striker 5.1, 5.2, 5.3 thus strikes against the heart 3.1, 3.2, 3.3 with a well-defined zero reset force, which corresponds to the maximum winding force of the striker spring 5.1, 5.2, 5.3 reached in the position shown in fig. 2 c. The striker spring 5.1, 5.2, 5.3 has been wound by the force of the user. The energy accumulated at this stage is sufficient to complete the zero reset. The springs 5.1, 5.2, 5.3 nevertheless remain wound, i.e. the springs 5.1, 5.2, 5.3 are still partially wound when the rams 4.1, 4.2, 4.3 bear against the hearts 3.1, 3.2, 3.3. In fact, once applied against the pressure hearts, the rams 5.1, 5.2, 5.3 exert a retaining force on these hearts 3.1, 3.2, 3.3 which corresponds to the residual winding force of the ram springs 5.1, 5.2, 5.3 in the position shown in fig. 2 d. Then, by continuing to press the button, the user continues to wind the spring 5.1, 5.2, 5.3, although the hammer 4.1, 4.2, 4.3 has pressed against its heart 3.1, 3.2, 3.3, thereby keeping the pressure on the heart. However, in order to avoid any damage, the course of the push button 1, of the second control means 2, and also of the winding and release means 6, and therefore the pressure on the heart 3.1, 3.2, 3.3, is limited by a winding stop 6.8 against which the free end 2.2 bears when the user has finished pressing on the push button 1. It should be noted with regard to the position shown in fig. 2d that the movement of the zero reset rams 4.1, 4.2, 4.3 towards the zero reset cams 3.1, 3.2, 3.3 and their abutment on the respective heart are done independently and not hindered by the control bar 8, in particular at the level of the second 4.2 and third 4.3 rams, given the play of the second 8.2 and third 8.3 pivots in their respective openings in the return bar 8.

Fig. 2e is a plan view of the device in its position, the first control means having been released by the user, so that the zero-reset rams 4.1, 4.2, 4.3 and also the locking means 7 have returned to their rest position. In fact, when the user releases the push button 1, the control return spring pushes the second control means 2 and also the winding and release means 6 into the rest position shown in fig. 1 b. In this return phase, the free end 2.2 of the second control device 2 bears against the first striker 4.1. From this moment, the three rams 4.1, 4.2, 4.3 leave the hearts 3.1, 3.2, 3.3 by means of the second control device 2, respectively, the return bar 8. The ram springs 5.1, 5.2, 5.3 are restored while the winding and releasing device 6 and the rams 4.1, 4.2, 4.3 return into their rest positions. At the same time, the locking pin 7.2 slides on the guide portion 4.1.5 of the first ram 4.1 until it engages the recess 4.1.4 in the first ram 4.1 due to the action of the locking return spring which presses the locking means 7 against the locking stop 7.3. The device is thus again in its rest position and ready to be used again.

A second embodiment of the zero-reset device according to the invention is shown schematically and by way of example in fig. 3a to 3 c. If the other elements of this device are identical to the device according to the first embodiment, except for having a different shape or positioning, which does not cause a substantial difference, the return means 8 are formed in the second embodiment of the device by the auxiliary arms 4.1.2, 4.2.2, 4.3.2, which auxiliary arms 4.1.2, 4.2.2, 4.3.2 are arranged on at least one of the zero-reset rams 4.1, 4.2, 4.3. These auxiliary arms 4.1.2, 4.2.2, 4.3.2 thus replace the return bars 8 provided in the first embodiment and ensure further independence between the respective zero-reset rams 4.1, 4.2, 4.3, since in this case, even at a level of negligible friction, as in the first embodiment, there is no longer any direct kinematic connection between the rams 4.1, 4.2, 4.3 during the operating phase of the device (during which they move towards or are applied against the cams 3.1, 3.2, 3.3).

In addition, fig. 3a to 3c also emphasize: the device according to this second embodiment can advantageously be equipped with zero-reset rams 4.1, 4.2, 4.3, these zero-reset rams 4.1, 4.2, 4.3 all having the same geometry, so that they have the same weight and moment of inertia. This allows to further improve the accuracy of the moment the rams strike their respective hearts, given that the rams in this figure should all exhibit the same behavior except for manufacturing tolerances.

It is also noted in fig. 3a to 3c that the hammer springs 5.1, 5.2, 5.3 of the second embodiment of the device are preferably formed by leaf springs having two resilient arms, of which the first arm is used to transmit the winding force by means of the winding and releasing device 6, similar to the free end of the leaf spring of the first embodiment of the device, and of which the second arm is used to transmit the winding force to the respective zero-reset hammer 4.1, 4.2, 4.3 once the spring has been wound. The bases of these ram springs 5.1, 5.2, 5.3 (which are arranged between two resilient arms) are preferably mounted concentrically on the zero-return rams 4.1, 4.2, 4.3 with respect to the respective pivot pins 4.1.1, 4.2.1, 4.3.1.

The zero-reset device according to the second embodiment functions completely similarly to what has been explained with reference to fig. 2a to 2e (fig. 2a to 2e show the zero-reset device according to the first embodiment), with the difference in the fact that: it is the auxiliary arm 4.1.2, 4.2.2, 4.3.2 of the zero-reset ram 4.1, 4.2, 4.3, instead of the return bar 8 provided in the first embodiment, which maintains the distance between the three rams and ensures a further improved independence between the zero-reset rams 4.1, 4.2, 4.3 during their phase of impact on the respective heart 3.1, 3.2, 3.3. Fig. 4a to 4e correspond to fig. 2a to 2e, and: shown in fig. 4a is a plan view of the second embodiment of the device in its position just after the start of the first phase of actuation of the first control device 1; in figure 4b is shown a plan view of this device in its position during the first phase of said actuation, at the instant in which the winding and release means 6 are in contact with the locking means 7; shown in fig. 4c is a plan view of the device in its position at the end of the first phase of said actuation, just before the instant at which the winding and release means 6 cause the release of the zero reset ram by pushing the locking means 7, so that said locking means releases the zero reset ram 4.1 with which said locking means cooperates 4.1; shown in fig. 4d is a plan view of the device in its position during the second phase of actuation in which the zero reset rams 4.1, 4.2, 4.3 have impinged on the respective zero reset cams 3.1, 3.2, 3.3; in fig. 4e, which is a plan view of the device in its position, the first control device 1 has been released by the user so that the zero reset rams 4.1, 4.2, 4.3 and the locking device 7 have returned to their rest positions so that the device is again ready for use.

Given the arrangement and action of the devices described above, it will be understood that the zero reset is only carried out when the manual force exerted by the user of the timepiece on the first control device 1 exceeds a predetermined threshold value, which generally corresponds to the sum of the winding force of the striker spring 5.1, 5.2, 5.3 and the winding force of the control return spring. In addition, the zero return force exerted by each hammer on the cam is always the same and corresponds to a predetermined value (that is, the above-mentioned maximum winding force of the hammer springs 5.1, 5.2, 5.3), which can make the reliability of the action of the device higher. These advantages are obtained while ensuring maximum independence of the rams which are not kinematically connected directly between them, at least during their application against the cam, which improves the precision of the simultaneous actuation of the rams. The second embodiment is particularly advantageous in this respect, since it does not provide any direct kinematic connection that may occur between the rams during their impact phase. In addition, the same geometry of all the rams provided also in the second embodiment of the device only enhances these advantages. In addition, the structure is robust and also as compact as possible, as well as simple and reliable during use. The zero-reset device according to the invention can be integrated in any type of timepiece, in particular in a mechanical watch, in particular in a chronograph watch or wristwatch with flyback hands. However, it is also possible to use the device in an electronic watch.

Claims (17)

1. Zero-reset device for a timepiece, comprising a first control means (1), a second control means (2), at least two zero-reset cams (3.1, 3.2, 3.3), at least two respective zero-reset rams (4.1, 4.2, 4.3), kinematically connected to the first control means (1), the at least two respective zero-reset rams (4.1, 4.2, 4.3) pivoting independently of each other and being adapted to be actuated so as to cooperate with the respective zero-reset cams (3.1, 3.2, 3.3), characterized in that it comprises at least two ram springs (5.1, 5.2, 5.3) each adapted to exert a pretension that pivots the zero-reset rams (4.1, 4.2, 4.3) in the direction of the respective zero-reset cams (3.1, 3.2, 3.3), and in that the zero-reset means comprise a release device (6) and a winding device (7), the winding and releasing device (6) being adapted to wind the hammer spring (5.1, 5.2, 5.3) during a first phase of actuation of the first control device (1), and adapted to cooperate with said locking means (7) during a second phase of actuation of said first control means (1), so that the locking device (7) is transferred from a first rest position to a second release position, in the first rest position, the locking device (7) holds the zero-reset striker (4.1, 4.2, 4.3) in its rest position, in the second release position, the locking device (7) releases the zero-reset striker (4.1, 4.2, 4.3), these zero-reset hammers come into their position of cooperation with the respective zero-reset cam (3.1, 3.2, 3.3) under the action of the respective hammer spring (5.1, 5.2, 5.3) in each case.

2. Zero-reset device according to claim 1, characterized in that the winding and releasing means (6) are kinematically connected to the second control device (2) and are formed by a bar comprising at least two winding elements, each of these winding elements being adapted to bear against a respective hammer spring (5.1, 5.2, 5.3) so as to be able to wind the hammer spring (5.1, 5.2, 5.3) during the first phase of actuation of the first control device (1).

3. Zero reset device according to claim 2 characterized in that the winding element is formed by a winding pin (6.1, 6.2, 6.3).

4. The zero-reset device according to claim 1, characterized in that the winding and release device (6) comprises a release portion (6.4) adapted to cooperate with the locking device (7) so that the locking device is transferred during the second phase of actuation of the first control device (1) from its first rest position, in which the locking device (7) holds the zero-reset ram (4.1, 4.2, 4.3) in its rest position, to its second release position, in which the locking device (7) releases the zero-reset ram (4.1, 4.2, 4.3).

5. Zero reset device according to claim 4 characterized in that the release part (6.4) is formed by an inclined plane or a rounded edge which can be in contact with the locking device (7).

6. The zero reset device according to any one of claims 2 to 5 characterized in that the winding and releasing device (6) is movable in large radius rotations around a guide shaft (6.6) fitted in a longitudinal groove (6.5) in the winding and releasing device (6) after actuation of the first control device (1), the kinematic connection between the winding and releasing device (6) and the second control device (2) being formed by a pivot pin (6.7).

7. The zero-reset device according to any one of claims 1 to 5, characterized in that the locking device (7) is formed by a locking lever which is pivotably mounted and prestressed against one of the zero-reset rams (4.1, 4.2, 4.3), which comprises a recess (4.1.4), with which recess (4.1.4) the locking portion (7.2) of the locking device (7) can be engaged/disengaged, respectively.

8. Zero-reset device according to claim 7, characterized in that the locking portion (7.2) is formed by a pin or by a part having a shape adapted to engage with the notch (4.1.4) in one of the zero-reset rams (4.1, 4.2, 4.3).

9. The zero-reset device according to any of claims 1 to 5, characterized in that it comprises a return device (8) of the zero-reset ram (4.1, 4.2, 4.3) adapted to return the zero-reset ram (4.1, 4.2, 4.3) into its rest position after its actuation.

10. Zero-reset device according to claim 9, characterized in that the return means (8) of the zero-reset ram are formed by auxiliary arms (4.1.2, 4.2.2, 4.3.2) arranged on at least one of the zero-reset rams (4.1, 4.2, 4.3).

11. The zero-reset device according to claim 9, characterized in that the return means (8) of the zero-reset ram are formed by a return bar kinematically connected to each of the zero-reset rams (4.1, 4.2, 4.3), said connection being produced without play for the zero-reset ram (4.1) cooperating with the locking means (7) and with play for the other zero-reset rams (4.2, 4.3).

12. Zero-reset device according to any of claims 1 to 5, characterized in that the zero-reset rams (4.1, 4.2, 4.3) all have the same geometry.

13. The zero reset device according to any one of claims 1 to 5 characterized in that the first control device (1) is movable in a translational manner and the second control device (2) is movable in a rotational manner.

14. Zero reset device according to any of claims 1 to 5 characterized in that the first control device (1) is a push button.

15. A zero-reset device according to any of claims 1 to 5, characterized in that it is used in a chronograph watch.

16. A timepiece comprising a chronograph or flyback hands mechanism incorporating a zero reset device according to any one of claims 1 to 15.

17. The timepiece according to claim 16, wherein the timepiece is a mechanical watch.