Chronograph reset system

A system (1) for resetting a chronograph is provided with a chronograph counting geartrain (2), which includes a minute counter having a minute wheel set (4), and a seconds counter, which includes a chronograph wheel set (3). The system includes a hammer held blocked by blocking device (11) and displaceable from an inactive position, where the hammer is blocked by the blocking device, and an active position, when the hammer is unblocked, for resetting the chronograph in contact with the various wheel sets (3, 4); a flexible element (10) connected between a reset controller (12) and the hammer for resetting the chronograph, and configured to store energy during a displacement of the controller and before unblocking the hammer blocked by the blocking device to be able, when the hammer is unblocked, to restore this stored energy and drive the hammer to reset the chronograph.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to European Patent Application No. 20161120.9 filed Mar. 5, 2020, the entire contents of which are incorporated herein by reference.

FIELD OF THE INVENTION

The invention relates to a chronograph reset system. The system is provided with a chronograph counting geartrain, which comprises at least a minute counter having a minute wheel set, and a seconds counter, which comprises a chronograph wheel set. The system comprises a hammer held blocked by a blocking means and able to be displaced from an inactive position, where the hammer is blocked by the blocking means, and an active position, when the hammer is unblocked, for resetting the chronograph in contact with the various wheel sets.

BACKGROUND OF THE INVENTION

Generally, a chronograph mechanism comprises a chronograph counting geartrain, which allows time to be counted from the second by means of a chronograph wheel set or seconds counter, to the minute by means of a minute counter, and optionally to the hour by means of an hour counter. Each counter comprises an indicator organ displacing on a corresponding graduated scale. When the chronograph is reset, the indicator organs are conventionally indexed to an angular position corresponding to the zero of each graduated scale. For this purpose, each indicator organ is generally carried by the axis of a corresponding element of the geartrain. The connection between the geartrain element and its axis is frictional, so as to allow for these two organs an independent angular displacement, beyond a certain torque. The indicating organs are indexed by means of heart-piece mechanisms and corresponding hammers. The use of frictional connections and heart-piece and hammer mechanisms means that the torque to be supplied when resetting the various counters can be large, and a lot of energy is consumed.

By way of comparison, in a conventional chronograph timepiece, a device called “buckling” device is often used. Such a device creates a hard point when pressing a push-button and once the hard point has passed, by an inertia effect the resetting function is performed. It should be noted that the spring pressed and which has passed the hard point has a negative friction effect throughout its resetting function, and a large amount of energy is consumed.

Under these conditions, a means must be found allowing this energy consumed only for resetting the various counters to be compensated for. An additional barrel can be used to provide the necessary energy, but problems of congestion are observed compared to the other basic elements of the timepiece. It is therefore important to have other mechanisms available for resetting the chronograph.

Patent application EP 2 884 350 A2 describes a device for resetting a chronograph watch. The device comprises in particular hammers and hammer blocking means. Springs are disposed between control means and each hammer. The reset hammers can pivot independently of each other and cooperate with a corresponding reset cam, to reset the chronograph.

SUMMARY OF THE INVENTION

The purpose of the invention is therefore to overcome the disadvantages of the prior art by providing a chronograph reset system, in particular a timepiece. An objective of the invention is specifically to benefit from an accumulation of energy of a flexible element, such as an embedded spring, linked to a hammer to restore this energy when the hammer is unblocked for the resetting of the chronograph.

To this end, the invention relates to a chronograph reset system, which comprises the features defined in the independent claim 1.

Particular embodiments of the reset system are defined in the dependent claims 2 to 15.

An advantage of the chronograph reset system according to the invention lies in the fact that it comprises a flexible element fastened by a first end to an upper end of a hammer, and by a second end to a first portion of a control lever rotatably mounted on a base or a frame or a plate of the timepiece. During a chronograph reset operation, an external activation organ, such as a push-button, is pressed on a second portion of the control lever causing the lever to rotate around its axis of rotation, and thus to drive the second end of the flexible element, such as an embedded spring, with a certain force so that it stores energy during this operation.

Another advantage of the chronograph reset system according to the invention lies in the fact that it comprises a means for blocking the hammer, which is preferably a hook organ rotatably mounted on a base or a frame or a plate of the timepiece and blocking the hammer by a fixed pin mounted on the hammer when the hook at a first end hooks onto the pin. Before pushing the second end of the hook organ by one end of the second portion of the control lever, this end of the second portion of the control lever is initially remote from and facing the second end of the hook organ. Thus, during the action of the push-button pushing the second portion of the control lever, the flexible element is stressed and stores energy even before the second end of the hook organ is pushed. This flexible element still stores energy until the hook of the first end of the hook organ is no longer in contact with the blocking pin. After that, the hammer is driven by the first end of the flexible element having stored enough energy which it restores to operate a reset of the chronograph.

Thus, the system allows energy to be stored by means of the flexible element to perform a function of resetting the chronograph, and also allows clear triggering without friction by means of the hook organ when unblocking the hammer to reset the chronograph.

DETAILED DESCRIPTION OF THE INVENTION

In the following description, elements of a chronograph reset system, which are well known in this technical field, will be described only briefly.

FIGS.1aand1bshow a bottom view of the main elements of a system1for resetting a chronograph in a position before the resetting operation. It is normally also composed of a chronograph counting geartrain2shown in more detail inFIGS.4and5described below. It can be considered to mount the reset system1in a timepiece comprising a basic time movement and a chronograph movement, which can be autonomous with its own movement, and therefore its own barrel. However, it can also be provided to use the basic movement of the timepiece with the chronograph.

The reset system1comprises a chronograph wheel set3, which is normally the seconds wheel set, which is part of the chronograph counting geartrain2ofFIGS.4and5. This chronograph counting geartrain comprises in particular a minute counter, which comprises a minute wheel set4, and a seconds counter, which comprises a chronograph wheel set3. The chronograph counting geartrain may also comprise an hour counter, which comprises an hour wheel set5. The chronograph or seconds wheel set3includes a heart-piece13mounted on the central axis23of the chronograph wheel set, this heart-piece13constitutes a cam shape. The minute wheel set4includes a heart-piece14mounted on the central axis24. Finally, the hour module5includes a heart-piece15mounted on the central axis25.

It should be noted that a timepiece equipped with a chronograph usually comprises chronograph wheel sets, which are mounted to pivot in friction on a frame or a plate of the timepiece. This means that when resetting the chronograph, it is possible to rotate, with sufficient torque, the wheel sets held only by friction by their axis in an opening provided for this purpose, until the chronograph reset indication.

The reset system1mainly comprises a flexible element10, which may be an embedded spring, which is connected between a reset control means12and an end part of the hammer6, which is used for resetting the chronograph. The flexible element10is configured so as to store energy during a displacement of the control means12and before unblocking the hammer6blocked by a blocking means11to be able, when the hammer6is unblocked, to restore this stored energy and drive the hammer6to reset the chronograph.

Primarily, the flexible element10is linked by a first end10ato the hammer6, for example to an end portion of the hammer6used for resetting the chronograph. A pin19is inserted at the first end10aof the flexible element10and is housed in an elongated opening9formed at a flat upper end of the hammer6. The second end10bof the flexible element10is fastened to the control means12, which is mounted on the base or the frame or the plate of the timepiece, and is used during the resetting operation of the chronograph. The flexible element10, such as the embedded spring, is arcuate in shape between its first end10aand its second end10b. This shape which is arcuate in the direction of an external activation organ B, such as a push-button, which can act on the control means12, can be adapted to improve the energy stored before resetting the chronograph.

The control means12is preferably a control lever, for example a flat control lever, which is rotatably mounted preferably by a fastening element22, which is rather a screw22passing through a central opening of the control lever and which is fixedly screwed into a corresponding thread in the base or the frame or the plate of the timepiece. This control lever12, which is rotatably mounted about the axis defined by the screw22, comprises a first portion on a first side of the axis, on which the second end10bof the flexible element10is fastened by stud-bolts40or other fastening means. The control lever12further comprises a second portion on a second side of the axis of rotation opposite to the first side, and at one end of which can act a push-button B in order to reset the chronograph. As explained below according to the invention, in a blocked position, the hammer6is held blocked by a blocking means11. Just before resetting the chronograph, the push-button B presses the second rotating portion of the control lever12and therefore acts first of all on the flexible element from its second end10bto perform an accumulation of energy before the effective unblocking of the hammer6, which occurs by pressing the push-button B even further.

The hammer6is preferably a metal plate, and is mounted in translation with a first longitudinal opening7and a second longitudinal opening8wherein are placed fixed rods17,18, which are for example a first screw17and a second screw18. These two screws17,18can be screwed into threads provided for this purpose on a base or a frame or a plate of the timepiece not shown, but leaving the hammer free to move between an inactive blocking position and an active reset position. The two longitudinal openings7,8are preferably of the same length and on the same line over the length of the hammer6. The length of the longitudinal openings is adapted such that the hammer6can occupy an inactive blocking position and an active reset position of the chronograph in contact with the various heart-pieces13,14of the wheel sets3,4or also of the heart-piece15of the wheel set5explained below.

The blocking means11of the hammer6is preferably a hook organ11rotatably mounted on the hammer6. The flat-shaped hook organ11comprises a central opening through which passes the second screw18, the thread of which is in the second longitudinal opening8of the hammer6defined as the upper side of the hammer6, where the push-button B acts. The hook organ11comprises at a first end11a, a hook for hooking onto a pin26fastened vertically on the hammer6near the second longitudinal opening8and between the two longitudinal openings7,8of the hammer6. The second end11bof the hook organ11, which is located on an opposite side relative to the axis of rotation of the second screw18, comprises a rod21by which a first free end of a return spring31of the hook organ11can act to return the hook organ11to a blocked position of the hammer6. A second end of the return spring31can be fastened by a screw51screwed into a corresponding thread made in the base or the frame or the plate of the timepiece.

For a chronograph reset operation, an inner end12′ of the second portion of the rotary control lever12is disposed facing and remote from the second end11bof the hook organ11. When the push-button B is pressed for a reset operation of the chronograph, the flexible element10first of all stores energy by the rotation of the control lever12after the pressure on the push-button B. The flexible element10already stores energy before the inner end12′ of the second portion of the control lever12pushes the second end11bof the hook organ11, until the hook of the first end11aof the hook organ11no longer hooks the pin26of the hammer6, which allows a clear triggering without additional friction. In this state, the hammer6is no longer in a blocked position and can act more easily to reset the chronograph thanks firstly to restoring the energy stored by the flexible element10and subsequently by the pressure of a user on the push-button B.

Thanks to this energy stored by the flexible element10just before the unblocking of the hammer6, the resetting operation of the chronograph is facilitated. The hammer6is pushed by the flexible element10from its first end10aand in the direction of the various wheel sets3,4,5, in particular the heart-pieces13,14,15of the wheel sets. For this purpose and in the case of the three wheel sets available, the hammer6comprises three contact portions16a,16b,16c. A first contact portion16adisposed on the hammer6contacts the heart-piece13of the chronograph wheel set3. A second contact portion16bdisposed on the hammer6contacts the heart-piece15of the hour wheel set5. The first contact portion16aand the second contact portion16bform an assembly rotatably mounted about an axis37on the hammer6near the first longitudinal opening17. An angular stop36is provided between the first contact portion16aand the second contact portion16b. This stop36passes with a certain clearance within a central opening of the assembly, which allows the geometric defects of the components to be compensated for. Finally, a third contact portion16cdisposed on the hammer6near the first end10aof the flexible element10, contacts the heart-piece14of the minute wheel set4. This third contact portion16cis connected by a U-shaped metal strip, and its end opposite the contact portion is fastened by stud-bolts43or other fastening means to the upper end of the hammer6. An adjustment eccentric44is fastened in a hole corresponding to the upper end of the hammer6to adjust the position of the third contact portion16c.

The position of these three wheel sets3,4,5and of the contact portions16a,16b,16cat the end of the resetting of the chronograph, are shown explicitly inFIGS.3aand3b, which will not be described in more detail since they comprise the same elements described above inFIGS.1aand1b. Each flat of the heart-pieces13,14,15are held in a zero position by each respective contact portion16a,16b,16c. The screws or other rods17and18, which are in each longitudinal opening7and8, are at a high end of the longitudinal openings7and8when resetting and before being placed in an inactive blocked position of the hammer6after the push-button B is released. The length of each longitudinal opening7and8is determined in such a way that each screw17and18can displace from an inactive position during the blocking of the hammer6and an active reset position.

For purely illustrative purposes, a minute hand34must be frictionally connected on the axis24to indicate the chronograph minutes on a dial of the timepiece which is not shown. An hour hand35must be frictionally connected on the axis25to indicate the chronograph hours on the dial of the timepiece which is not shown. The same can be done for the chronograph seconds indication, but no hand is shown.

In order to return the flexible element10to its initial position after the push-button B is released, it can be provided to have another return spring32, a free end32aof which contacts in a housing41made in the first portion of the rotary control lever12under the second end10bof the flexible element10. The other end32bof the return spring32is fastened by means of a screw42, which is screwed into a corresponding thread produced in the base or the frame or the plate of the timepiece. Once the flexible element10and the push-button B are in an initial position, the return spring31pushes the hook organ11into its blocking position of the hammer in a conventional manner before a next reset operation of the chronograph.

FIG.2, which only shows the bottom view of the chronograph reset system, just allows the energy stored by the flexible element10to be illustratively seen just before unblocking the hammer6when the hook at the first end11aof the hook organ11releases it from the blocking. By the rotation of the control lever12, the second end10bof the flexible element10tends to rotate in the clockwise direction, straightening the flexible element10and thus storing the energy to be restored when resetting the chronograph. Of course, all the other components ofFIG.2will not be repeated as they have already been explained with reference toFIGS.1aand1b.

FIGS.4and5below show a chronograph counting geartrain2, which comprises on the one hand a minute geartrain inFIG.4and on the other hand an hour geartrain inFIG.5. The various wheels for the minute geartrain and the hour geartrain are shown connected by dotted lines. Mainly in the case of the minute geartrain, which is shown inFIG.4, a first toothed wheel62disposed on the axis23of the chronograph wheel set3meshes with an intermediate wheel63, the diameter of which is larger than the diameter of the first toothed wheel62. A second intermediate wheel64of smaller diameter is placed on the intermediate wheel63to drive an hour geartrain explained below. A third coaxial proximal intermediate wheel65and of smaller diameter than the intermediate wheel63allows a large wheel66mounted on the axis24of the minute wheel set4to be driven. The dimension of each wheel is of course determined according to the time counted and to be displayed to switch from the second with a first indicator organ to the minute with a second indicator organ, such as a hand34on a dial which is not shown.

FIG.5mainly represents the hour wheel. The first toothed wheel62disposed on the axis23of the chronograph wheel set3meshes with the intermediate wheel63, the diameter of which is larger than the diameter of the first toothed wheel62. The second intermediate wheel64of smaller diameter meshes with a second intermediate wheel68of larger diameter which in turn comprises below another small intermediate wheel which is intended to drive another large wheel67, of which a proximal wheel of smaller diameter on the same axis drives an hour wheel69. The dimension of each wheel is of course determined according to the time counted and to be displayed in order to switch from the second with a first indicator organ to the hour with a third indicator organ, such as a hand35on a dial which is not shown.

It can also be noticed inFIGS.4and5, the minute34and hour35indication hands which are not directly connected to their respective axes of the wheel sets4and5. The heart-pieces14and15of the minute and hour wheel sets4and5are each disposed under the wheels66and69. Both the minute geartrain and the hour geartrain are well known in this technical field of a chronograph timepiece. No other details will be explained more precisely.

FIG.6shows a bottom view of the main elements of another embodiment of a system1for resetting a chronograph in a position before the resetting operation. The same elements described inFIG.1awill therefore not be repeated, but on the other hand, the new elements are described in relation to the hook organ11and a new third contact portion16c.

The hook organ11is rotatably mounted about an axis45at a first end, and the second end11bis in contact with an inner end12′ of the second portion of the control lever12. A support11aof an intermediate part of the hook organ11is disposed in contact with the pin26of the hammer6.

The new third contact portion16cis a so-called flexible pane, which comprises flexible blades46used to adjust the force in contact with the heart-piece14. These flexible blades46are disposed on either side of the central part of the so-called flexible pane, and substantially parallel to each other. This so-called flexible pane is fastened on one end of the hammer6by means of screws or stud-bolts43in the oblong-shaped openings to adjust the positioning before fastening. With this configuration of this so-called flexible pane, this allows the geometric defects of the components to be compensated for and ensures a correct reset by an identical contact on the three heart-pieces of the wheel sets (hyperstatic system). It is no longer necessary in this configuration to use a mechanical adjustment as shown in particular inFIG.1aand subsequent figures.

From the description which has just been given, multiple variant embodiments of the reset system for resetting a chronograph can be designed by the person skilled in the art without departing from the scope of the invention defined by the claims. Provision can be made of one or more flexible elements of identical or different shape, and disposed between one end of the hammer and the control lever. In addition, it can be considered to have one or more hammers which are rotary and not with linear movement for resetting the chronograph.