Chronograph mechanism and method for mounting a chronograph mechanism

Abstract

The invention relates to a chronograph mechanism (10) for a timepiece movement (1) comprising a reset mechanism (100) comprising a first hammer (110) and a second hammer (120) that are configured on two levels in order to cooperate respectively with a first reset member (51) for resetting to zero a first chronograph counter and a second reset member (52) for resetting to zero a second chronograph counter, these reset members not being coplanar; the first hammer (110) and the second hammer (120) being pivotable about an axis of rotation (105) independently of one another, the reset mechanism (100) comprising an elastic locking member (116), constrained to rotate with the first hammer (110), cooperating with an indexing finger (118), constrained to rotate with the second hammer (120), to ensure an elastic rotational coupling of the first hammer (110) and the second hammer (120) about the axis of rotation (105), the elastic locking member (116) being configured to lock the indexing finger (118) in a predetermined relative angular position, causing the first hammer (110) or the second hammer (120) to rotate about the axis of rotation (105).

Description

CHRONOGRAPH MECHANISM AND METHOD FOR ASSEMBLING A CHRONOGRAPH MECHANISM Technical field of the invention

[0001] The present invention relates to a chronograph mechanism for a watch movement.

[0002] More specifically, the invention relates to a chronograph mechanism comprising a mechanism for resetting the chronograph counters.

[0003] The invention also relates to a method for assembling a chronograph mechanism. Technological background

[0004] Chronograph mechanisms allow time to be measured on demand via several chronograph counters, for example minutes and seconds.

[0005] Chronograph mechanisms typically include a reset mechanism for resetting the chronograph counters, i.e., repositioning them in a reference position, so that time can be measured again on demand.

[0006] Typically, such a reset mechanism consists of a reset control that can be operated by the user, for example via a pusher or an actuation pin accessible from outside the case in which the watch movement is mounted.

[0007] The reset control cooperates directly or indirectly via rocker arms with reset hammers which strike the reset cams carried by the various chronograph counters.

[0008] The return to zero of the chronograph counters, and associated hands, is achieved by the pressure of the hammers on the periphery of the reset cams generating a driving torque modifying the position of the chronograph counters in question until they return to a reference position determined by the geometry of the hammers and the reset cam.

[0009] In existing chronograph mechanisms, the hammers are either manufactured as a single piece or formed from separate parts joined together by means of fastening. In this latter case, they share a common activation control. An example of such an implementation is described in EP 2241945.

[0010] Adjusting the reset mechanisms is a complex and time-consuming process requiring skilled craftsmanship. To adjust such a mechanism, the seconds hammer must be brought into contact with the seconds reset cam in its reference position. Then, the tip of the minutes hammer must be filed so that the minutes reset cam is also in its reference position. This operation is lengthy and delicate and can only be performed by a specialized watchmaker.

[0011] One solution to overcome this restrictive adjustment is to use two superimposed hammers whose angular movement is synchronized, while allowing limited relative angular movement of one hammer compared to the other during reset. Such a solution is described in patent CH 220536. This approach allows both hammers to act simultaneously on their respective hearts and prevents the chronograph counter hands from shifting to the reference position.

[0012] However, with such a solution, the overlapping hammers come into contact with the reset cams with low energy because A large portion of the actuation energy is absorbed by the return and damping spring, which exerts increasing force against the hammer movements. Therefore, there is a risk that the chronograph counters will not be correctly zeroed with such a mechanism.

[0013] Therefore, there is a need to improve chronograph mechanisms and in particular the mechanisms for resetting the counters of such chronograph mechanisms. Summary of the invention

[0014] In this context, one of the objectives of the invention is to propose a chronograph mechanism that solves at least one of the problems raised previously.

[0015] One of the objectives of the invention is to provide a reset mechanism that offers a precise reset of the various chronograph counters.

[0016] One of the objectives of the invention is to provide a reliable and secure reset mechanism.

[0017] In this context, the invention relates to a chronograph mechanism for a watch movement comprising a reset mechanism including a first hammer and a second hammer configured on two levels to cooperate respectively with a first reset member of a first chronograph counter and a second reset member of a second non-coplanar chronograph counter; the first hammer and the second hammer being pivotable about an axis of rotation independently of each other, characterized in that the reset mechanism includes an elastic locking member, rotationally fixed to the first hammer, cooperating with an indexing finger, rotationally fixed to the second hammer, to ensure elastic rotational coupling of the first hammer and the second hammer about said axis of rotation, the elastic locking member being configured to lock the indexing finger in a predetermined relative angular position of the hammers, by imparting a rotation of the first hammer or the second hammer around said axis of rotation.

[0018] In addition to the characteristics mentioned in the preceding paragraph, the chronograph mechanism according to the invention may have one or more additional characteristics from among the following, considered individually or in all technically possible combinations: - the elastic locking member comprises a first elastic arm and a second elastic arm defining an elastic retaining housing configured to hold the indexing finger in the locked position; - the elastic locking device ensures a rotational coupling between the first hammer and the second hammer in the absence of a force, greater than a value predetermined by the stiffness of at least one of the elastic arms of the elastic locking device, applied to one of the hammers; - the first elastic arm forms a first elastic stop to block the movement of the indexing finger in a first direction of rotation of the second hammer as long as a force, greater than the stiffness of the first elastic arm, is not applied to the second hammer; - the second elastic arm forms a second elastic stop to block the movement of the indexing finger in a second direction of rotation S2 of the second hammer; - the second elastic arm is configured to deform elastically under the stress of the indexing finger to allow the indexing finger to pass into said housing elastic retention in the first direction of rotation S1 of the second hammer; - the first hammer has a stop located near the first elastic arm to limit the amplitude of elastic deformation of the first elastic arm; - the indexing finger has two shoulders arranged in opposition on either side of a contact portion intended to be in contact with the first elastic arm and the second elastic arm at the level of the elastic retaining housing, the two shoulders being configured to axially secure the two elastic arms in a direction parallel to said axis of rotation; - said elastic locking member comprises a single elastic arm having an elastic retaining housing configured to hold the indexing finger in the locked position; - the elastic locking device ensures a rotational coupling between the first hammer and the second hammer in the absence of a force, greater than a value predetermined by the stiffness of said single elastic arm of the elastic locking device, applied on one of the hammers; - the elastic retaining housing includes a first stop to block the movement of the indexing finger in a first direction of rotation of the second hammer as long as a force, greater than the stiffness of the first elastic arm, is not applied to the second hammer; - the elastic retaining housing includes a second stop to block the movement of the indexing finger in a second direction of rotation of the second hammer; - the elastic arm is configured to deform elastically under the stress of the indexing finger to allow the indexing finger to pass into said elastic retaining housing in the first direction of rotation of the second hammer; - the first hammer has a stop designed to limit the amplitude of elastic deformation of the elastic arm; - the indexing finger has two shoulders (arranged in opposition on either side of a contact portion intended to be in contact with the elastic retaining housing, the two shoulders being configured to axially secure the single elastic arm in a direction parallel to said axis of rotation; - the chronograph mechanism includes a user-operable reset control configured to set the first hammer in rotation.

[0019] The invention also relates to a watch movement comprising a chronograph mechanism according to the invention.

[0020] The invention also relates to a timepiece comprising a clockwork movement according to the invention.

[0021] The invention also relates to a method of assembling a chronograph mechanism and more particularly the set of hammers of the reset mechanism.

[0022] More specifically, the assembly process comprises a step of pivotally assembling the first and second hammers on the axis of rotation and a step of elastically coupling the first hammer with the second hammer, said step being carried out by modifying the relative angular position of the two hammers until the elastic locking member elastically locks the indexing finger in position, in a predetermined angular position, thus locking the relative position of the two hammers.

[0023] Preferably, the elastic coupling step is automated. Brief some

[0024] The aims, advantages and features of the present invention will become apparent from the detailed description below, which refers to the following figures: - Figure 1 is a partial schematic representation of an example of the realization of a chronograph mechanism for a watch movement comprising a mechanism for resetting the chronograph counters according to the invention; - Figure 2 is an exploded view illustrating more precisely the two-hammer system of the reset mechanism shown in Figure 1, elastically coupled by an elastic coupling element; - Figures 3 to 5 illustrate different relative positions of the two hammers during coupling and locking in position of the two hammers by the elastic locking member; - Figure 6 schematically illustrates the main steps of a method for assembling a chronograph mechanism according to the invention; - Figure 7 illustrates an exploded view showing a second example of the chronograph counter reset mechanism, and more specifically the system of two hammers elastically coupled by an elastic coupling element.

[0025] In all figures, common elements bear the same reference numbers unless otherwise specified. detailed description of the invention

[0026] Figure 1 is a partial schematic representation, in top view, of a chronograph mechanism 10 integrated into a watch movement 1 according to the invention.

[0027] With reference to figure 1, the clockwork movement 1 includes a plate 2 which serves as a support for the various elements of the clockwork movement 1, in particular a timekeeping gear (not shown) dedicated to the division of time which is driven by a source of energy (not shown).

[0028] The chronograph mechanism 10 includes a chronograph gear train 20 which can be kinematically linked, on demand, with the time train, via a clutch (not shown) controlled by a chronograph start / stop control.

[0029] For example, the clutch is a rocker clutch that allows a clutch wheel to pivot. Other clutch designs known to those skilled in the art are also applicable.

[0030] The chronograph gear train 20 includes in particular a first chronograph counter comprising a first chronograph counter wheel 21, for example a wheel of a seconds counter, and a second chronograph counter comprising a second chronograph counter wheel 22, for example a wheel of a minutes counter.

[0031] The first seconds counter wheel 21 is coupled to a first shaft, called the seconds counter shaft, which drives a chronograph seconds hand (not shown). The first shaft also carries a first reset mechanism 51, which is fixed to the shaft for rotation.

[0032] The second minute counter wheel 22 is coupled to a second shaft, called the minute counter shaft, driving a hand chronograph minutes (not shown). The second shaft also carries a second reset mechanism 52, fixed to the rotation of the shaft.

[0033] The first tree and the second tree are coaxial.

[0034] The first seconds counter wheel 21 and the second minutes counter wheel 22 are superimposed and arranged in two separate, superimposed, and parallel planes. The respective reset mechanisms 51 and 52 are also superimposed with respect to each other.

[0035] The reset devices 51, 52 are for example snail-shaped, heart-shaped, or other reset cams, the shape of which allows the needles to be repositioned in a reference position under the action of reset hammers.

[0036] In the example shown, the reset organs 51, 52 are reset cores.

[0037] As shown in Figure 1, the chronograph gear train 20 may also include a third additional counter, for example an hour counter, comprising a third chronograph counter wheel 23 associated with a third reset organ 53.

[0038] The chronograph gear train 20 may include intermediate chronograph wheels (not shown) to obtain the desired ratios between the different counter wheels 21, 22, 23 of the chronograph mechanism 10.

[0039] The chronograph mechanism 10 also includes a reset mechanism 100 for resetting the various chronograph counters, and a repositioning to the reference position of the reset organs 51, 52, 53 and the associated hands, a first example of which is illustrated with reference to figures 1 to 5.

[0040] The reset mechanism 100 comprises a first hammer 110 and a second hammer 120, superimposed one on top of the other, and shaped to cooperate respectively with the first reset element 51 of the first chronograph counter and the second reset element 52 of the second chronograph counter. The hammers 110, 120 are driven in rotation by a reset control 60 which can be manipulated by the user, for example via a pusher or an actuation pin 61.

[0041] The reset control 60 is movable in rotation around a rotation axis 66 and cooperates directly or indirectly with one of the hammers 110, 120.

[0042] In the illustrated embodiment, the reset control 60 cooperates directly with the first hammer 110, located in the lower position (i.e., the proximal hammer of the stage 2). However, the reset control 60 can also cooperate directly with the second hammer 120, located in the upper position (i.e., the distal hammer of the stage 2).

[0043] For this purpose, the first hammer 110 includes an activation element 113, for example a pin, a gauge, mounted projecting securely on the body of the first hammer 110, configured to cooperate in direct contact with a portion of the reset control 60.

[0044] Figure 2 illustrates in particular an exploded view of the assembly of hammers 110, 120 superimposed according to the invention.

[0045] The first hammer 110 and the second hammer 120 are mounted pivoting about a common axis of rotation 105, extending perpendicularly to the general plane formed by the plate 2. The two hammers 110, 120 are mounted pivoting independently of each other.

[0046] The first hammer 110 includes an elastic locking member 116, rotationally fixed to the first hammer 110, cooperating with an indexing finger 118, rotationally fixed to the second hammer 120 for to achieve a rotational elastic coupling between the two hammers 110, 120. Of course, the second hammer 120 can be fixed to the elastic locking member 116 and the first hammer 110 can be fixed to the indexing finger 118.

[0047] In particular, the elastic locking member 116 and the indexing finger 118 allow the first hammer 110 and the second hammer 120 to be coupled in rotation in an elastic manner to allow a certain relative angular flexibility between the two hammers 110, 120 during the reset, and more particularly of the second hammer 120 with respect to the first hammer 110, by elastic deformation of the elastic locking member 116, when a force, greater than a predetermined value, defined by the stiffness of the elastic locking member 116, is applied on one of the hammers 110, 120, more particularly the second hammer 120 in the illustrated embodiment example since in the example shown the reset control 60 is engaged with the first hammer 110 to drive it in rotation.

[0048] The elastic locking member 116 according to the invention facilitates the mounting and assembly of the two hammers 110, 120 in the watch movement 1. The elastic locking member 116 also facilitates the rotational coupling of the two hammers 110, 120, which are freely mounted on the rotation axis 105, by relative rotation of the two hammers 110, 120. Thanks to the invention, the rotational elastic coupling is achieved when the second hammer 120 is positioned in a certain predetermined angular position relative to the first hammer 110.

[0049] More specifically, the elastic locking member 116 comprises a first elastic arm 116.1 and a second elastic arm 116.2. The two elastic arms 116.1, 116.2 have a free end and join at their opposite end to a central body 116.3 which is rotationally fixed to the body of the first hammer 110.

[0050] The free ends of the two elastic arms 116.1, 116.2 define an elastic retaining housing 116.4 intended to receive the indexing finger 118, and to elastically hold the indexing finger 118 in the locked position to ensure the rotational coupling of the two hammers 110, 120, as long as a force greater than the stiffness of the elastic arms 116.1, 116.2 is not applied to one of the hammers 110, 120.

[0051] The elastic retaining housing 116.4 is bordered by a first elastic stop 116.5 formed by a portion of the free end of the first elastic arm 116.1 and by a second elastic stop 116.6 formed by a portion of the free end of the second elastic arm 116.2.

[0052] Preferably, the first elastic stop 116.5 and the second elastic stop 116.6 are spaced at a distance equal to or less than the dimension of the indexing finger 118, so that the elastic stops 116.5, 116.6 exert a pinching force around the indexing finger 118 when it is in the locked position in the elastic retaining housing 116.4, in particular to avoid unwanted rattling or oscillation of the indexing finger 118 in the elastic retaining housing 116.4.

[0053] Preferably, the first elastic stop 116.5 of the first elastic arm 116.1 is arranged to block the movement of the indexing finger 118 in a first direction of rotation S1, for example counterclockwise, of the second hammer 120 relative to the first hammer 110. When a force greater than a value corresponding to the stiffness of the first elastic arm 116.1 is applied to the second hammer 120, the elastic locking member 116, and more particularly the first elastic arm 116.1, deforms elastically allowing a certain angular freedom of the second hammer 120 relative to the first hammer 110.

[0054] Preferably, the second elastic stop 116.6 of the second elastic arm 116.2 is arranged to block the movement of the indexing finger 118, in a second direction of rotation S2, for example clockwise, of the second hammer 120 relative to the first hammer 110. Thus, the second elastic stop 116.6 prevents the decoupling of the two hammers 110, 120, once the indexing finger 118 is locked in position in the elastic retaining housing 116.4.

[0055] Preferably, the first elastic stop 116.5 and the second elastic stop 116.6 are arranged substantially perpendicular to the circular trajectory of the indexing finger 118.

[0056] The second elastic arm 116.2 has an engagement portion 116.7 located at a distance from the free end and the second elastic stop 116.6. In the rest position, or free state, of the second elastic arm 116.2, this engagement portion 116.7 is located on the circular path of the indexing finger 118. During the coupling of the hammers 110, 120 by relative rotation between the two hammers 110, 120, the indexing finger 118 comes to rest on the engagement portion 116.7 of the second hammer 120 so as to constrain the second arm 116.2 and to elastically deform the second arm 116.2, until the indexing finger 118 constrains and deforms the second arm 116.2 to allow the passage of the indexing finger 118 to the elastic retaining housing 116.4 to ensure its elastic clipping and locking in position.

[0057] When the indexing finger 118 is no longer under tension on the second elastic arm 116.2, the latter is free to return to its neutral position, or close to its neutral position by elastic return, so that the second elastic stop 116.6 comes into contact with the indexing finger 118 and opposes a relative clockwise rotational movement of the second hammer S2. The indexing finger 118 is then locked in the elastic retaining housing 116.4 and the second hammer 120 is rotationally coupled with the first hammer 110 to perform the reset function.

[0058] Of course, the rotational coupling of the two hammers is reversible, so it is possible to decouple the two hammers 110, 120 by example during maintenance of the watch movement 1. For this, it is sufficient to constrain the second arm 116.2 using an ad-hoc tool to position it outside the circular path of the indexing finger 118, so as to disengage the indexing finger 118 from the elastic retaining housing 116.4.

[0059] To limit the amplitude of elastic deformation of the first elastic arm 116.1 when coupling the two hammers 110, 120, in particular in the event of application of too great a rotational force on the second hammer 120, and thus avoid any risk of plastic deformation of the first elastic arm 116.1, the latter may include a deformation limiting stop (not shown).

[0060] Preferably, the indexing finger has two shoulders 118.1, 118.2 arranged in opposition on either side of a contact portion 118.3, intended to be in contact with the first and second stops 116.5, 116.6 of the elastic arms 116.1, 116.2. The two shoulders 118.1, 118.2 are shaped to axially secure the two elastic arms 116.1, 116.2 in a direction parallel to the axis of rotation 105, and in particular to prevent a loss of coupling of the two hammers 110, 120 in operation, or during a shock.

[0061] The first hammer 110 has a first peen 107 configured to strike the first reset mechanism 51 of the first counter. The second hammer 120 has a second peen 126 configured to strike the second reset mechanism 52 of the second counter.

[0062] In a stable position, that is, without exerting any force on the second hammer 120 exceeding a predetermined value related to the stiffness of the elastic arms 116.1, 116.2, and more specifically the first elastic arm 116.1, of the elastic locking member 116, the second purlin 126 of the second hammer 120 is not aligned with the first purlin 107 of the first hammer 110. Indeed, the second purlin 126 of the second hammer 120 has a slight forward offset (i.e. in the direction of the reset devices 51, 52) relative to the first breakdown 107 of the first hammer 110.

[0063] The advance of the second purlin 126 of the second hammer 120 ensures that the two reset members 51, 52 will be in their reference position at the end of the movement of the hammers 110, 120 and the reset control 60. Indeed, during the actuation of the hammers 110, 120, once the second reset member 52 of the second counter is in the reset position, an additional angular displacement of the hammers 110, 120 will generate on the second purlin 126 of the second hammer 120 a force greater than the stiffness of the elastic locking member 116, which will allow the first reset member 51 of the first counter to continue to be reset if it is not yet in the reference position. A retrograde movement of the second hammer 120 relative to the first hammer 110 is therefore initiated by going against the elastic force of the elastic coupling member 116.

[0064] Figure 7 illustrates in particular an exploded view of a second example of the embodiment of a set of hammers 110, 120 of a reset mechanism 100 according to the invention.

[0065] In this second example of implementation, the set of hammers 110, 120 is identical to the first example of implementation except for the elements which will be specified later.

[0066] The first hammer 110 includes an elastic locking member 216, rotationally fixed to the first hammer 110, cooperating with an indexing finger 118, rotationally fixed to the second hammer 120 to achieve a rotationally elastic coupling between the two hammers 110, 120. Of course, the second hammer 120 can be fixed to the elastic locking member 216 and the first hammer 110 can be fixed to the indexing finger 118.

[0067] More specifically, the elastic locking member 216 and the indexing finger 118 allow the first hammer 110 and the second hammer 120 to be coupled in rotation in an elastic manner to allow a certain relative angular flexibility between the two hammers 110, 120 during the reset, and more particularly of the second hammer 120 with respect to the first hammer 110, by elastic deformation of the elastic locking member 216, when a force, greater than a predetermined value, defined by the stiffness of the elastic locking member 216, is applied on one of the hammers 110, 120, more particularly the second hammer 120 in the illustrated embodiment example since in this embodiment example shown in figure 7, the reset control 60 is engaged with the first hammer 110 to drive it in rotation, in the same way as the first embodiment example.

[0068] The elastic locking member 216 is configured to ensure rotational coupling of the two hammers 110, 120 which are mounted freely on the rotation axis 105, by relative rotation of the two hammers 110, 120. Thanks to the invention, the rotational elastic coupling is achieved when the second hammer 120 is positioned in a certain predetermined angular position relative to the first hammer 110.

[0069] More specifically, the elastic locking member 216 comprises a single elastic arm 216.1 having a free end 216.2 in the shape of a hook, opposed to a central body 216.3 fixed in rotation to the body of the first hammer 110.

[0070] The free end 216.2 defines an elastic retaining housing 216.4 intended to receive the indexing finger 118, and to elastically hold the indexing finger 118 in the locked position to ensure the rotational coupling of the two hammers 110, 120, as long as a force greater than the stiffness of the elastic arm 216.1 is not applied to one of the hammers 110, 120.

[0071] The elastic retaining housing 216.4 is delimited by a first stop 216.5 and by a second stop 216.6.

[0072] Preferably, the first stop 216.5 and the second stop 216.6 are spaced at a distance equivalent to the dimension of the indexing finger 118, so that the stops 216.5, 216.6 ensure that the indexing finger 118 is held when it is in the locked position in the elastic retaining housing 216.4, in particular to avoid unwanted rattling or oscillation of the indexing finger 118 in the elastic retaining housing 216.4.

[0073] Preferably, the first stop 216.5 is arranged to block the movement of the indexing finger 118 in a first direction of rotation S1, for example counterclockwise, of the second hammer 120 relative to the first hammer 110. When a force greater than a value corresponding to the stiffness of the first elastic arm 116.1 is applied to the second hammer 120, the elastic locking member 216 deforms elastically allowing a certain angular freedom of the second hammer 120 relative to the first hammer 110.

[0074] Preferably, the second stop 216.6 is arranged to block the movement of the indexing finger 118, in a second direction of rotation S2, for example clockwise, of the second hammer 120 relative to the first hammer 110. Thus, the second stop 216.6 prevents the decoupling of the two hammers 110, 120, once the indexing finger 118 is locked in position in the elastic retaining housing 216.4.

[0075] Preferably, the first stop 216.5 and the second stop 216.6 are arranged substantially perpendicular to the circular trajectory of the indexing finger 118.

[0076] The free end 216.2 has an engagement portion 216.7 located at a distance from the elastic retaining housing 216.4. In the rest position, or free state, this engagement portion 116.7 lies on the circular path of the indexing finger 118. During the coupling of the hammers 110, 120 by relative rotation between the two hammers 110, 120, the finger indexing finger 118 comes to rest on the engagement portion 216.7 of the elastic arm 216.1 so as to constrain the free end 216.2 and deform it elastically until the indexing finger 118 constrains and deforms sufficiently the elastic arm 216.1 to allow the positioning of the indexing finger 118 with regard to the elastic retaining housing 216.4 so as to ensure elastic clipping of the indexing finger 118 in the elastic retaining housing 216.4 and its locking in position in the elastic retaining housing 216.4, by elastic return of the elastic arm 216.1 to its neutral position, or close to its neutral position. Once the indexing finger 118 is engaged in the elastic retaining housing 216.4, the second stop 216.6 is in contact with the indexing finger 118 to oppose a relative rotational displacement of the second hammer in the clockwise direction S2.The indexing finger 118 is then locked in the elastic retaining housing 216.4 and the second hammer 120 is coupled in rotation with the first hammer 110 to ensure the zeroing function.

[0077] Of course, the rotational coupling of the two hammers is reversible, so it is possible to decouple the two hammers 110, 120 for example during maintenance of the watch movement 1. For this, it is sufficient to constrain the elastic arm 216.1 using an ad-hoc tool to position it outside the circular path of the indexing finger 118, so as to disengage the indexing finger 118 from the elastic retaining housing 216.4.

[0078] The operation of the chronograph mechanism described above is as follows. When the user applies pressure to the reset control 60, via the actuation pin 61, the reset control 60 pivots around its axis of rotation 66, which has the effect of engaging the first hammer 110 via the activation element 113 and pivoting the first hammer 110 around the axis of rotation 105.

[0079] In the absence of any effort applied to the second failure 126 of the second hammer 120, the second hammer 120 is coupled in rotation to the first hammer 110, it is therefore also set in motion by the reset control 60 and pivots around the axis of rotation 105.

[0080] The two hammers 110, 120 continue their angular movement under the action of the reset control 60 until the pegs 107, 126 strike the respective reset devices 51, 52.

[0081] Given the advance of the second breakdown 126 of the second hammer 120, the second reset member 52 will be returned to the reference position before reaching the full angular stroke of the reset control 60.

[0082] By continuing, the angular displacement of the reset control 60, the second reset member 52 of the second counter, being in the reference position which is a stable position, induces a force on the second breakdown 126 greater than the stiffness of the elastic locking member 116, 216, which has the effect of elastically deforming the first elastic arm 116.1 of the elastic locking member 116, or the single elastic arm 216 of the locking member 216 illustrated in figure 7, and of modifying the relative position of the two hammers 110, 120. This elastic decoupling between the two hammers 110, 120 allows the first hammer 110 to continue its angular displacement, driven by the reset control 60, to ensure a complete reset of the first reset member 51 of the first counter.

[0083] At the end of the stroke of the reset control 60, the two breakdowns 116 and 126 are aligned with each other and the two reset devices 51, 52 are positioned in their reference position.

[0084] The second hammer 120 also includes a third peen 127 configured to return the third reset device 53 to the reference position.

[0085] Typically, the reset control 60 cooperates with an elastic reset element (not shown) configured to reposition the reset control 60 to the neutral rest position between each user activation.

[0086] The reset mechanism 100 may also include a retaining element (not shown) to secure the reset mechanism 100 and ensure full actuation of the reset control 60. The retaining element is configured to momentarily prevent the actuation of the reset control 60, and thus of the hammers 11, 120, until a certain force is applied to the reset control 60. Such a retaining element is a safety device preventing an unwanted reset of the chronograph mechanism hands 10. The retaining element exhibits dynamic behavior similar to a mechanical fuse.

[0087] As shown in the various figures, the chronograph mechanism 10 includes a column wheel 63 to control the various movements of different levers that bear against a column or between two columns. The operation of a chronograph mechanism 10 with such a column wheel 63 is widely known, so further explanation of its function is unnecessary.

[0088] Of course, the chronograph mechanism 10 can also be a cam chronograph mechanism in place of the column wheel 63 without going out of the context of the invention.

[0089] The invention also relates to a timepiece, for example a wristwatch, comprising such a timepiece movement.

[0090] The invention also relates to an assembly method 400 for the chronograph mechanism 10 according to the invention, comprising the reset mechanism 100. More particularly, the assembly method according to the invention facilitates the assembly and elastic coupling of the two hammers 110, 120.

[0091] Referring to Figure 5, the assembly process 400 includes a step 410 of assembling the first hammer 110 and the second hammer 120 by pivoting them on the axis of rotation. The hammers 110 and 120 are positioned non-coplanarly.

[0092] The assembly process 400 also includes a step 420 of elastic coupling in rotation of the two hammers 110, 120. This coupling step is achieved simply by rotating one of the hammers relative to the other so as to modify its relative position with respect to the other hammer, until the indexing finger 118 locks into the elastic retaining housing 116.4, 216.4 of the elastic locking member 116, 216. Thus, the relative angular position of the two hammers 110, 120 is locked and the two hammers 110, 120 are coupled in rotation while allowing a certain elastic flexibility permitted by the elastic arm(s) 116.1, 116.2, 216.1.

Claims

DEMANDS 1. Chronograph mechanism (10) for watch movement (1) comprising a reset mechanism (100) including a first hammer (110) and a second hammer (120) configured on two levels to cooperate respectively with a first reset member (51) of a first chronograph counter and a second reset member (52) of a second non-coplanar chronograph counter;the first hammer (110) and the second hammer (120) being pivotable about an axis of rotation (105) independently of each other, characterized in that the reset mechanism (100) comprises an elastic locking member (116, 216), rotationally fixed to the first hammer (110), cooperating with an indexing finger (118), rotationally fixed to the second hammer (120), to ensure an elastic rotational coupling of the first hammer (110) and the second hammer (120) about said axis of rotation (105), the elastic locking member (116, 216) being configured to lock the indexing finger (118) in a predetermined relative angular position of the hammers (110, 120), by imparting a rotation of the first hammer (110) or of the second hammer (120) about said axis of rotation (105).

2. Chronograph mechanism (10) for watch movement (1) according to the preceding claim characterized in that said elastic locking member (116) comprises a first elastic arm (116.1) and a second elastic arm (116.2) defining an elastic retaining housing (116.4) configured to hold the indexing finger (118) in the locked position.

3. Chronograph mechanism (10) for a watch movement (1) according to the preceding claim, characterized in that the elastic locking member (116) ensures rotational coupling between the first hammer (110) and second hammer (120) in the absence of a force, greater than a value predetermined by the stiffness of at least one of the elastic arms (116.1 , 116.2) of the elastic locking member (116), applied on one of the hammers (110, 120).

4. Chronograph mechanism (10) for watch movement (1) according to any one of claims 2 to 3 characterized in that the first elastic arm (116.1) forms a first elastic stop (116.5) to block the movement of the indexing finger (118) in a first direction of rotation (S1) of the second hammer (120) as long as a force, greater than the stiffness of the first elastic arm (116.1) is not applied on the second hammer (120).

5. Chronograph mechanism (10) for watch movement (1) according to any one of claims 2 to 4 characterized in that the second elastic arm (116.2) forms a second elastic stop (116.6) to block the movement of the indexing finger (118) in a second direction of rotation (S2) of the second hammer (120).

6. Chronograph mechanism (10) for watch movement (1) according to the preceding claim, characterized in that the second elastic arm (116.2) is configured to deform elastically under the stress of the indexing finger (118) to allow the passage of the indexing finger (118) in said elastic retaining housing (116.4) in the first direction of rotation (S1) of the second hammer (120).

7. Chronograph mechanism (10) for watch movement (1) according to any one of claims 2 to 6, characterized in that the first hammer (110) has a stop provided to limit the amplitude of elastic deformation of the first elastic arm (116.1).

8. Chronograph mechanism (10) for clock movement (1) according to any one of claims 2 to 7, characterized in that the indexing finger (118) has two shoulders (118.1, 118.2) arranged in opposition on either side of a contact portion (118.3) intended to be in contact with the first elastic arm (116.1) and the second elastic arm (116.2) at the level of the elastic retaining housing (116.4), the two shoulders (118.1, 118.2) being configured to axially secure the two elastic arms (116.1, 116.2) in a direction parallel to said axis of rotation (105).

9. Chronograph mechanism (10) for watch movement (1) according to claim 1 characterized in that said elastic locking member (216) comprises a single elastic arm (216.1) having an elastic retaining housing (216.4) configured to hold the indexing finger (118) in the locked position.

10. Chronograph mechanism (10) for watch movement (1) according to claim 9 characterized in that the elastic locking member (216) ensures a rotational coupling between the first hammer (110) and the second hammer (120) in the absence of a force, greater than a value predetermined by the stiffness of said single elastic arm (216.1) of the elastic locking member (216), applied on one of the hammers (110, 120).

11. Chronograph mechanism (10) for watch movement (1) according to any one of claims 9 to 10 characterized in that the elastic retaining housing (216.4) has a first stop (216.5) to block the movement of the indexing finger (118) in a first direction of rotation (S1) of the second hammer (120) as long as a force, greater than the stiffness of the first elastic arm (116.1) is not applied to the second hammer (120).

12. Chronograph mechanism (10) for a watch movement (1) according to any one of claims 9 to 11, characterized in that the housing elastic retaining (216.4) includes a second stop (216.6) to block the movement of the indexing finger (118) in a second direction of rotation (S2) of the second hammer (120).

13. Chronograph mechanism (10) for watch movement (1) according to claim 12, characterized in that the elastic arm (216.1) is configured to deform elastically under the stress of the indexing finger (118) to allow the passage of the indexing finger (118) in said elastic retaining housing (216.4) in the first direction of rotation (S1) of the second hammer (120).

14. Chronograph mechanism (10) for watch movement (1) according to any one of claims 9 to 13, characterized in that the first hammer (110) has a stop provided to limit the amplitude of elastic deformation of the elastic arm (216.1).

15. Chronograph mechanism (10) for watch movement (1) according to any one of claims 9 to 14, characterized in that the indexing finger (118) has two shoulders (118.1, 118.2) arranged in opposition on either side of a contact portion (118.3) intended to be in contact with the elastic retaining housing (116.4), the two shoulders (118.1, 118.2) being configured to axially secure the single elastic arm (216.1) in a direction parallel to said axis of rotation (105).

16. Chronograph mechanism (10) for watch movement (1) according to any one of the preceding claims characterized in that the chronograph mechanism (10) includes a user-operable reset control (60) configured to set the first hammer (110) into rotational motion.

17. Clock movement (1) comprising a chronograph mechanism (10) according to any one of claims 1 to 16.

18. Timepiece comprising a timepiece movement (1) according to the preceding claim.

19. Method for assembling (400) a chronograph mechanism (10) comprising a reset mechanism (100) according to any one of claims 1 to 16, characterized in that the method comprises the following steps: - a step (410) of assembling the first hammer (110) and the second hammer (120) in a pivoting manner on the axis of rotation (105); - a step (420) of elastic coupling of the first hammer (110) with the second hammer (120), said step being carried out by modifying the relative angular position of the two hammers (110, 120) until the elastic locking member (116, 216) elastically locks the indexing finger (118) in a predetermined angular position, blocking the relative position of the two hammers (110, 120).

20. Method of assembling (400) a chronograph mechanism (10) according to the preceding claim characterized in that said elastic coupling step (420) is automated.

Images