Chronograph mechanism and method for assembling the chronograph mechanism

Abstract

This invention provides a chronograph mechanism and a method for assembling a chronograph mechanism. [Solution] The zero reset mechanism 100 comprises a first hammer 110 and a second hammer 120, a pre-support mechanism 115 on the elastic coupling mechanism 116 positioned on the second hammer 120 to ensure pre-assembly of the elastic coupling mechanism 116 on the second hammer 120, and a clip-on mechanism 118 configured to ensure that the first hammer 110 and the second hammer 120 are rotatably elastically coupled during relative axial displacement between the first hammer 110 and the second hammer 120 in a direction parallel to the rotation axis 105 of the hammers 110 and 120 when assembling the hammers 110 and 120 by moving the elastic coupling mechanism 116 to its operating position where the first bracket 116.1 presses the clip-on mechanism 118.

Description

Technical Field

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

[0002] More specifically, the present invention relates to a chronograph mechanism comprising a mechanism for zero-resetting a chronograph counter.

[0003] The present invention also relates to a method of assembling a chronograph mechanism.

Background Art

[0004] A chronograph mechanism enables time to be measured on demand using a plurality of chronograph counters, such as minutes and seconds.

[0005] A chronograph mechanism typically comprises a zero-reset mechanism for resetting the chronograph counter, thereby returning the chronograph counter to a reference position so that time can be measured on demand again.

[0006] Conventionally, such a zero-reset mechanism consists of a zero-reset control unit that can be operated by a user via a button or an operating pusher stud accessible from the outside of an intermediate part to which a watch movement is attached.

[0007] The zero-reset control unit engages directly or indirectly, via a lever, with a zero-reset hammer that strikes a zero-reset cam held by various chronograph counters.

[0008] The chronograph counter and the corresponding hand are reset to zero when the hammer presses the reset cam, and a driving couple is generated to change the position of the chronograph counter until the chronograph counter returns to the reference position determined by the shapes of the hammer and the reset cam.

[0009] In existing chronograph mechanisms, the hammers are either formed from a single piece or consist of separate parts fixed to one another by fastening means. In this case, they share a common actuation control unit. Exemplary embodiments are described in particular in European Patent Application No. 2241945.

[0010] Setting the zero-reset mechanism is complex, time-consuming, and requires skilled craftsmanship. In fact, to set such a mechanism, the seconds hammer must be in contact with the seconds zero-reset cam in its reference position. Next, the pin on the minute hammer must be pushed down so that the minute zero-reset cam is also in its reference position. This operation is time-consuming and complex, and can only be performed by a professional watchmaker.

[0011] One solution to this cumbersome setting operation is to use two overlapping hammers. These two overlapping hammers are conjugate in their angular motion, while allowing for a limited relative angular motion of one hammer relative to the other during zero reset. Such a solution is described in particular in Swiss Patent No. 220536. In particular, this approach allows both hammers to act simultaneously on their respective heart pieces, which helps prevent the chronograph hands from shifting at the reference position.

[0012] However, in such a solution, most of the operating energy is absorbed by the return and damper springs, which exerts increasingly greater stress on the hammer's movement, causing the overlapping hammers to contact the zero-reset cam with almost no energy. Therefore, there is a risk that the chronograph counter will not be set to zero precisely in such a mechanism.

[0013] Therefore, an improved chronograph mechanism is needed, in particular a zero-reset mechanism for the counters on such a chronograph mechanism. [Prior art documents] [Patent Documents]

[0014] [Patent Document 1] European Patent Application No. 2241945 [Patent Document 2] Swiss Patent No. 220536 [Overview of the project] [Problems that the invention aims to solve]

[0015] For this purpose, the present invention aims to provide a chronograph mechanism that provides a solution to at least one of the aforementioned problems.

[0016] One of the objectives of the present invention is to provide a zero-reset mechanism that provides accurate zero-reset for various chronograph counters.

[0017] One of the objectives of the present invention is to provide a highly reliable and stable zero-reset mechanism. [Means for solving the problem]

[0018] For this purpose, the present invention provides a chronograph mechanism for a watch movement equipped with a zero-reset mechanism, the zero-reset mechanism is A first hammer and a second hammer, configured in two levels to engage with a first zero-reset mechanism on a first chronograph counter and a second zero-reset mechanism on a second chronograph counter, respectively, which are not on the same plane, the first hammer and the second hammer pivot independently of each other about at least one axis of rotation, The present invention relates to a chronograph mechanism comprising an elastic coupling mechanism positioned between a first hammer and a second hammer, having an operating position in which the first bracket presses against the first hammer and the second bracket presses against the second hammer.

[0019] The zero-reset mechanism further comprises: a pre-support mechanism on the elastic coupling mechanism, positioned on the second hammer and configured to support the first bracket on the elastic coupling mechanism in a pre-assembled position; and a clip-on mechanism fixed to the first hammer, which engages with the first bracket on the elastic coupling mechanism and is configured to ensure that the first and second hammers are rotatably elastically coupled during relative axial displacements between the first and second hammers in a direction parallel to the axis of rotation of the hammers, when assembling the hammers by moving the elastic coupling mechanism to its operating position in which the first bracket presses the clip-on mechanism.

[0020] In addition to the features described in the previous paragraph, the chronograph mechanism according to the present invention may have one or more complementary features from the following, which may be taken individually or in any technically possible combination: The elastic coupling mechanism ensures a rotatable connection between the first and second hammers when the stress applied to one of the hammers does not exceed a predetermined value determined by the rigidity of the elastic coupling mechanism. The clip-on mechanism is configured to ensure deflection of the elastic coupling mechanism when assembling the two hammers, thereby the elastic coupling mechanism having a second compressed state in the operating position that is more compressed than the first compressed state of the elastic coupling mechanism in the pre-assembled position on the second hammer. The clip-on mechanism extends in a direction parallel to at least one axis of rotation of the hammer. The clip-on mechanism comprises a main body having a portion that forms a first support mechanism that supports the first bracket on the elastic coupling mechanism at the operating position of the elastic coupling mechanism, and an end cone that forms the free end of the clip-on mechanism. The first support mechanism on the first hammer has a recess for axially fixing the first bracket on the elastic coupling mechanism in an axial direction parallel to at least one axis of rotation of the hammer. The recess is formed near the base of the end cone. The second hammer comprises a second support mechanism configured to support a second bracket on the elastic coupling mechanism, and the second support mechanism has a recess for axially fixing the second bracket on the elastic coupling mechanism in an axial direction parallel to at least one rotation axis of the hammer. The chronograph mechanism comprises a zero reset control unit that can be actuated by a user and is configured to rotate the first hammer. The elastic coupling mechanism is formed to elastically restrain a second hammer that presses against the stop surface of the first hammer. The second hammer comprises a stop mechanism pressed by the support surface of the first hammer. The first hammer and the second hammer have a shared rotation axis or dedicated rotation axes parallel to each other.

[0021] The present invention also relates to a timepiece movement comprising a chronograph mechanism according to the present invention.

[0022] The present invention also relates to a timepiece comprising a timepiece movement according to the present invention.

[0023] The present invention also relates to a method of assembling a chronograph mechanism, and more particularly, to all of the hammers on the zero reset mechanism.

[0024] More particularly, the assembling method includes a step in which the elastic coupling mechanism is arranged on the second hammer, and the elastic coupling mechanism is held in a pre-assembled position in a first compressed state between a preliminary support mechanism held by the second hammer and a second support mechanism on the second hammer, and a step in which the first hammer and the second hammer are assembled by relative axial displacement of the two hammers in a direction parallel to at least one rotation axis, and the relative axial displacement between the two hammers ensures an elastic coupling between the two hammers by elastically deflecting the elastic coupling mechanism.

[0025] Preferably, the elastic coupling between the two hammers in the assembly step is achieved by a clip-on mechanism, which is fixed to the first hammer, engages with the elastic coupling mechanism in the pre-assembled position, and is configured to move the elastic coupling mechanism to the operating position in a second compressed state in which the elastic coupling mechanism is compressed between the clip-on mechanism and the second support mechanism on the second hammer.

[0026] The object, advantages, and features of the present invention will become apparent from the following detailed description with reference to the following drawings. [Brief explanation of the drawing]

[0027] [Figure 1] This is a partial schematic diagram of an exemplary embodiment of a chronograph mechanism for a watch movement, which includes a mechanism for zeroing out the chronograph counter according to the present invention. [Figure 2] This is an exploded view showing in more detail the dual hammer system of the zero-reset mechanism shown in Figure 1, which is elastically coupled by an elastic coupling mechanism. [Figure 3] This diagram shows in more detail the elastic coupling mechanism pre-assembled on the second hammer before the two hammers are assembled and rotatably joined. [Figure 4] This diagram more specifically illustrates an elastic coupling mechanism in which the elastic coupling mechanism is in an operating position that presses against the first and second hammers in order to rotatably connect the two hammers. [Figure 5] This diagram schematically illustrates the main steps in the method for assembling the chronograph mechanism according to the present invention. [Modes for carrying out the invention]

[0028] In all drawings, common elements shall have the same reference numeral unless otherwise specified.

[0029] Figure 1 is a schematic top view of a portion of the chronograph mechanism 10 incorporated into the watch movement 1 according to the present invention.

[0030] Referring to Figure 1, the clock movement 1 comprises a plate 2 that serves as a support for various elements of the clock movement 1, in particular for a regulating gear train (not shown) for a time scale, which is driven by an energy source (not shown).

[0031] The chronograph mechanism 10 comprises a chronograph sequence 20, which can be kinematically coupled to a time sequence on demand via a coupling (not shown) controlled by a chronograph start / stop control unit.

[0032] For example, the coupling is a lever coupling that allows the coupling wheel to pivot. Other modified couplings known to those skilled in the art can also be applied.

[0033] In particular, the chronograph row 20 comprises a first chronograph counter having a first chronograph counter wheel 21, for example, a seconds counter wheel, and a second chronograph counter having a second chronograph counter wheel 22, for example, a minutes counter wheel.

[0034] The first seconds counter wheel 21 is coupled to a first arbor called a seconds counter arbor, which drives the seconds hand on a chronograph (not shown). The first arbor also holds a first zero-reset mechanism 51 which is rotatably fixed to the arbor.

[0035] The second minute counter wheel 22 is coupled to a second arbor, known as a minute counter arbor, which drives the minute hand of the chronograph (not shown). The second arbor also holds a second zero-reset mechanism 52, which is rotatably fixed to the arbor.

[0036] The first arbor and the second arbor are coaxial.

[0037] The first wheel of the second counter 21 and the second wheel of the minute counter 22 overlap, are located in two separate planes, and are parallel to each other. The respective zero-reset mechanisms 51 and 52 also overlap each other.

[0038] The zero reset mechanisms 51 and 52 are, for example, snail-shaped, heart-shaped, or other zero reset cams, whose shape allows the zero reset mechanism to return the needle to its reference position when actuated by the zero reset hammer.

[0039] In the illustrated example, the zero-reset mechanisms 51 and 52 are zero-reset heart pieces.

[0040] As shown in Figure 1, the chronograph column 20 may also include a third additional counter, such as a time counter, which has a third chronograph counter wheel 23 connected to a third zero-reset mechanism 53.

[0041] The chronograph column 20 may include intermediate chronograph movable parts (not shown) to obtain a desired ratio between the various counter wheels 21, 22, and 23 on the chronograph mechanism 10.

[0042] The chronograph mechanism 10 also includes a zero-reset mechanism 100 for resetting various chronograph counters and returning the zero-reset mechanisms 51, 52, 53 and the corresponding hands to their reference positions.

[0043] The zero-reset mechanism 100 comprises a first hammer 110 and a second hammer 120 that overlap each other and are shaped to engage with a first zero-reset mechanism 51 on the first chronograph counter and a second zero-reset mechanism 52 on the second chronograph counter, respectively. The hammers 110 and 120 are rotated by a zero-reset control unit 60, which can be operated by the user, for example, via a button or an actuation brumstud 61.

[0044] The zero reset control unit 60 is rotatable around the rotation axis 66 and engages directly or indirectly with one of the hammers 110, 120.

[0045] In the illustrated exemplary embodiment, the zero-reset control unit 60 directly engages with a first hammer 110 located in a lower position (i.e., a hammer near plate 2). However, the zero-reset control unit 60 can also directly engage with a second hammer 120 located in an upper position (i.e., a distal hammer on plate 2).

[0046] For this purpose, the first hammer 110 includes an actuation element 113, such as a pin or prong, which is securely mounted on the body of the first hammer 110 so as to protrude and is configured to directly contact and engage with a portion of the zero reset control unit 60.

[0047] Figure 2 shows a more detailed exploded view of the set of overlapping hammers 110 and 120 according to the present invention.

[0048] The first hammer 110 and the second hammer 120 are mounted to pivot around a shared axis of rotation 105 that extends perpendicular to the overall plane formed by the plate 2. The two hammers 110 and 120 are mounted to pivot independently of each other.

[0049] According to the modified embodiment, the first hammer 110 and the second hammer 120 may have different axes of rotation that are parallel to each other.

[0050] The second hammer 120 has limited angular degrees of freedom relative to the first hammer 110. To this end, an angular motion limiting device can be placed between the first hammer 110 and the second hammer 120 to limit the angular movement of the second hammer 120 relative to the first hammer 110 around the rotation axis 105.

[0051] The elastic coupling mechanism 116 is positioned between the first hammer 110 and the second hammer 120, forming a rotatable elastic coupling between the two hammers 110 and 120.

[0052] More specifically, the elastic coupling mechanism 116 allows the first hammer 110 and the second hammer 120 to be rotatably coupled, while allowing relative angular degrees of freedom of the second hammer 120, by elastic strain of the elastic coupling mechanism 116, when a stress greater than a predetermined value defined by the rigidity of the elastic coupling mechanism 116 is applied to one of the hammers 110 or 120, more specifically to the second hammer 120 in the illustrated exemplary embodiment. This is because, in the illustrated example, the zero-reset control unit 60 engages with the first hammer 110 to rotate it.

[0053] More specifically, the elastic coupling mechanism 116 comprises a first elastic bracket 116.1 and a second elastic bracket 116.2. The two elastic brackets 116.1 and 116.2 are joined on an elbow-shaped central body 116.3. The elastic coupling mechanism 116 is, for example, a spring, a leaf spring, a chord spring, etc.

[0054] When the elastic coupling mechanism 116 is in its operating position, as specifically shown in Figure 4, the first bracket 116.1 presses against the first hammer 110, more specifically against the first support mechanism 111 on the first hammer 110, and the second bracket 116.2 presses against the second hammer 120, more specifically against the second support mechanism 112 on the second hammer 120.

[0055] The first support mechanism 111 and / or the second support mechanism 112 may be an element added to and fixed to the body of the hammer 110, 120, or may be made of the same material as the body of the hammer 110, 120.

[0056] In this operating position, the elastic coupling mechanism 116 is configured to suppress the second hammer 120 from pressing against the first hammer 110 when a stress greater than a predetermined value due to the rigidity of the elastic coupling mechanism 116 is not applied to the second hammer 120.

[0057] More specifically, the second hammer 120 is directed toward the first hammer 110 and includes a stopping mechanism 122 configured to engage with a complementary stopping surface 128 located on the first hammer 110. Under the elastic constraint of an elastic coupling mechanism 116 that presses against the two hammers 110, 120, the stopping mechanism 122 of the second hammer 120 is maintained in a state of being pressed against the stopping surface 128 of the first hammer 110.

[0058] The first hammer 110 includes a first pane 107 configured to strike a first zero-reset mechanism 51 on a first counter. The second hammer 120 includes a second pane 126 configured to strike a second zero-reset mechanism 52 on a second counter.

[0059] When in a stationary position, that is, when no stress greater than a predetermined value with respect to the stiffness of the elastic coupling mechanism 116 is applied to the second hammer 120, the second pane 126 on the second hammer 120 is not aligned with the first pane 107 on the first hammer 110. In fact, the second pane 126 on the second hammer 120 is slightly offset forward (i.e., in the direction of the zero-reset mechanisms 51, 52) relative to the first pane 107 on the first hammer 110.

[0060] The forward offset of the second pane 126 on the second hammer 120 ensures that at the end of the movement of the hammers 110, 120 and the movement of the zero-reset control unit 60, both zero-reset mechanisms 51, 52 return to their reference positions. In fact, when the hammers 110, 120 are actuated, and the second zero-reset mechanism 52 on the second counter is in the zero-reset position, the supplemental angular displacement of the hammers 110, 120 generates a stress in the second pane 126 of the second hammer 120 that is greater than the stiffness of the elastic coupling mechanism 116, thereby allowing the first reset mechanism 51 on the first counter to complete its zero-reset if it has not yet reached its reference position. The retrograde motion of the second hammer 120 relative to the first hammer 110 is thus initiated by counteracting the elastic stress of the elastic coupling mechanism 116.

[0061] The chronograph mechanism described below works as follows:

[0062] When the user presses the zero reset control unit 60 via the actuating bram stud 61, the zero reset control unit 60 pivots around its rotation axis 66, thereby engaging with the first hammer 110 via the actuating element 113, causing the first hammer 110 to pivot around the rotation axis 105.

[0063] When no stress is applied to the second pane 126 on the second hammer 120, the second hammer 120 is rotatably coupled to the first hammer 110 and is therefore also moved by the zero-reset control unit 60, pivoting around the rotation axis 105.

[0064] The two hammers 110 and 120 continue their angular motion under the action of the zero-reset control unit 60 until the pins 107 and 126 strike their respective zero-reset mechanisms 51 and 52.

[0065] As the second pin 126 advances on the second hammer 120, the second zero-reset mechanism 52 is reset to its reference position before the zero-reset control unit 60 reaches its full angular movement.

[0066] As the zero reset control unit 60 continues its angular displacement, the second zero reset mechanism 52 on the second counter, which is in a reference position which is a stationary position, exerts a stress on the second pane 126 that is greater than the stiffness of the elastic coupling mechanism 116. This stress elastically deforms the elastic coupling mechanism 116, changing the relative positions of the two hammers 110 and 120. This separation of the two hammers 110 and 120 allows the first hammer 110 to continue its angular motion driven by the zero reset control unit 60, ensuring that the first zero reset mechanism 51 on the first counter is completely reset.

[0067] When the zero reset control unit 60 reaches the end of its movement, the two panes 116 and 126 are aligned with each other, and the two zero reset mechanisms 51 and 52 are positioned at their reference positions.

[0068] The second hammer 120 further comprises a third pane 127 configured to reset the third zero-reset mechanism 53 to its reference position.

[0069] Advantageously, the zero-reset mechanism 100 is equipped with a pre-support mechanism 115 to ensure that the elastic coupling mechanism 116 is pre-supported in a fixed position and to facilitate the assembly of the two hammers 110 and 120 in the watch movement 1. The pre-support mechanism 115 also facilitates the installation of the elastic coupling mechanism 116 between the two hammers 110 and 120.

[0070] In the example shown in the figure, the pre-support mechanism 115 is positioned on the second hammer 110 so that the elastic coupling mechanism 116 can be pre-attached to the second hammer 120 before the two hammers 120 are assembled.

[0071] Of course, the pre-support mechanism 115 can also be positioned on the first hammer 110, which is a hammer actuated by the zero-reset control unit 60, so that the elastic coupling mechanism 116 can be pre-attached to the first hammer 110.

[0072] The pre-support mechanism 115 acts to elastically restrain the elastic coupling mechanism 116 on the second hammer 120 to a position known as the pre-assembled position. This position is shown particularly clearly in Figures 2 and 3.

[0073] The pre-support mechanism 115 is configured to support the first bracket 116.1 on the elastic coupling mechanism 116 so that the elastic coupling mechanism 116 can be elastically restrained to its pre-assembled position between the pre-support mechanism 115 and the second support mechanism 112 of the second hammer 120.

[0074] To pivot the elastic coupling mechanism 116 to its operating position when assembling the two hammers 110, 120 by relative axial displacement in a direction parallel to the rotation axis 105, the zero-reset mechanism 100 includes a clip-on mechanism 118 fixed to the hammer, which does not include the pre-support mechanism 115. In the illustrated exemplary embodiment, the clip-on mechanism 118 is positioned on the first hammer 110.

[0075] The clip-on mechanism 118 protrudes toward the second hammer 120 relative to the body of the first hammer 110. The clip-on mechanism 118 extends in a direction parallel to the rotation axis 105 of the hammers 110 and 120.

[0076] The clip-on mechanism 118 comprises a body 118a, part of which forms a first support mechanism 111 on the first hammer 110, and an end cone 118b located distal to the body of the first hammer and forming the free end of the clip-on mechanism 118.

[0077] The clip-on mechanism 118 is configured to contact the first bracket 116.1 on the elastic coupling mechanism 116 via the end cone 118b when the elastic coupling mechanism 116 is in a pre-assembled position on the second hammer 120. The end cone 118b engages the first bracket 116.1 and allows the first bracket 116.1 to be moved onto the support mechanism 111 on the first hammer by sliding it on the conical surface of the end cone 118b, thereby changing its support. When sliding on the conical surface of the end cone 118b, the elastic coupling mechanism is slightly compressed.

[0078] In particular, the first support mechanism 111 supports the first bracket 116.1 on the elastic coupling mechanism 116 and includes recesses 117, such as notches, cavities, recesses, and uneven surfaces, configured to fix the elastic coupling mechanism 116, more specifically the first bracket 116.1 on the elastic coupling mechanism 116, in an axial direction parallel to the rotation axis 105 of the hammers 110, 120. This prevents axial sliding of the first bracket 116.1 on the elastic coupling mechanism 116 and loss of support of the first bracket 116.1 on the first support mechanism 111 on the first hammer 110 when the two hammers 110, 120 are assembled.

[0079] The recess 117 is formed near the base of the end cone 118b. In addition to fixing the elastic coupling mechanism 116 axially, the recess 117 provides the watchmaker with auditory and tactile notification that the elastic coupling mechanism 116 is correctly positioned between the two hammers 110, 120, and therefore the elastic coupling of the two hammers 110, 120 is correctly positioned.

[0080] According to a modified embodiment, for example, a recess in the form of a notch, cavity, dimple, or uneven surface can be placed on the second support mechanism 112 of the second hammer 120 to support the second bracket 116.2 on the elastic coupling mechanism 116, thereby fixing the elastic coupling mechanism 116 in the axial direction.

[0081] Conventionally, the zero reset control unit 60 engages with an elastic zero reset element (not shown) configured to return the zero reset control unit 60 to a neutral locked position between each user's operations.

[0082] The zero-reset mechanism 100 may also include a retaining mechanism (not shown) to fix the zero-reset mechanism 100 and ensure that the zero-reset control unit 60 is fully operational. The retaining mechanism is configured to temporarily hold the operation of the zero-reset control unit 60, and consequently the operation of the hammers 110 and 120, unless a specific stress is applied to the zero-reset control unit 60. Such a retaining mechanism is a safety mechanism to prevent unintended zero-reset of the hands of the chronograph mechanism 10. The retaining member exhibits dynamic behavior similar to that of a mechanical fuse.

[0083] As shown in various diagrams, the chronograph mechanism 10 includes a column wheel 63 for pressing the columns or controlling the various movements of various levers located between the two columns. The operation of a chronograph mechanism 10 having such a column wheel 63 is widely known, so there is no need to further explain the operation of such a wheel.

[0084] Of course, the chronograph mechanism 10 may be a cam-mounted chronograph mechanism that replaces the column wheel 63 without departing from the scope of the present invention.

[0085] The present invention also relates to a timekeeping device, such as a wristwatch, that incorporates such a clock movement.

[0086] The present invention also relates to a method 400 for assembling a chronograph mechanism 10 according to the present invention, which is equipped with a zero-reset mechanism 100. More specifically, the assembly method according to the present invention facilitates the assembly and elastic coupling of two hammers 110, 120.

[0087] Referring to Figure 5, the method includes a step 410 in which the elastic coupling mechanism 116 is pre-mounted, which involves pre-positioning the elastic coupling mechanism 116 on one of the hammers, for example, the second hammer 120, so that the elastic coupling mechanism 116 is maintained in a pre-assembled position in a first compressed state between a pre-support mechanism 115 held by the second hammer 120 and a second support mechanism 112 on the second hammer 120. Figure 3 shows this first compressed state of the elastic coupling mechanism 116 in particular, in a fixed position on the second hammer 120.

[0088] Once the elastic coupling mechanism 116 is pre-attached to the second hammer 120, the method includes step 420, in which the two hammers 110, 120 are assembled by translating them in a direction parallel to the axis of rotation 105.

[0089] As the two hammers 110 and 120 converge axially, the clip-on mechanism 118 can contact the first bracket 116.1 on the elastic coupling mechanism 116 that presses against the pre-support mechanism 115. With axial displacement, the end cone 118b gradually compresses the elastic coupling mechanism 116, releasing pressure on the pre-support mechanism 115. As the first bracket 116.1 passes the base of the end cone 118b, the first bracket 116.1 is clipped into the recess 117 of the clip-on mechanism 118 by the elastic return of the first bracket 116.1, as shown in Figure 4. The elastic coupling mechanism 116 is then in its operating position, which is more compressed than the first compressed state in the pre-assembled position, in a second compressed state, pressing against the first hammer 110 and the second hammer 120 to ensure a rotatable elastic coupling between the two hammers 110 and 120. In the operating position, the elastic coupling mechanism 116 is fixed axially to prevent unintended contact loss. [Explanation of Symbols]

[0090] 1. Watch movement 10. Zero Reset Mechanism 100 Zero Reset Mechanism 51. First Zero Reset Mechanism 52 Second Zero Reset Mechanism 110 The First Hammer 120 The Second Hammer 105 Rotation axis 116 Elastic coupling mechanism 116.1 First bracket 116.2 Second bracket 115 Pre-support mechanism 118 Clip-on mechanism

Claims

1. A chronograph mechanism (10) for a watch movement (1) equipped with a zero-reset mechanism (100), wherein the zero-reset mechanism (100) is A first hammer (110) and a second hammer (120) configured in two levels to engage with a first zero-reset mechanism (51) on a first chronograph counter and a second zero-reset mechanism (52) on a second chronograph counter, respectively, wherein the first hammer (110) and the second hammer (120) pivot independently of each other around at least one axis of rotation (105), The system includes an elastic coupling mechanism (116) positioned between the first hammer (110) and the second hammer (120), having an operating position in which the first bracket (116.1) presses against the first hammer (110) and the second bracket (116.2) presses against the second hammer (120), The zero reset mechanism (100) is A preliminary support mechanism (115) for the elastic coupling mechanism (116) is positioned on the second hammer (120) and configured to support the first bracket (116.1) on the elastic coupling mechanism (116) in the pre-assembled position, A clip-on mechanism (118) fixed to the first hammer (110), which engages with the first bracket (116.1) on the elastic coupling mechanism (116), and is configured to ensure that when assembling the hammers (110, 120) by moving the elastic coupling mechanism (116) to its operating position where the first bracket (116.1) presses the clip-on mechanism (118), the first hammer (110) and the second hammer (120) are rotatably elastically coupled during relative axial displacement between them in a direction parallel to the at least one rotation axis (105), A chronograph mechanism (10) characterized by having the following:

2. The chronograph mechanism (10) according to claim 1, characterized in that the elastic coupling mechanism (116) ensures a rotatable coupling between the first hammer (110) and the second hammer (120) when there is no stress greater than a value predetermined by the rigidity of the elastic coupling mechanism (116) applied to one of the hammers (110, 120).

3. The chronograph mechanism (10) according to claim 1, wherein the clip-on mechanism (118) is configured to ensure deflection of the elastic coupling mechanism (116) when assembling the two hammers (120, 120), so that the elastic coupling mechanism (116) has a second compressed state at the operating position that is more compressed than the first compressed state of the elastic coupling mechanism (116) at the pre-assembled position on the second hammer (110).

4. The chronograph mechanism (10) according to claim 1, characterized in that the clip-on mechanism (118) extends in a direction parallel to the at least one axis of rotation (105) of the hammers (110, 120).

5. The chronograph mechanism (10) according to claim 1, characterized in that the clip-on mechanism (118) comprises a body (118a) having a portion that forms a first support mechanism (111) that supports the first bracket (116.1) on the elastic coupling mechanism (116) at the operating position of the elastic coupling mechanism (116), and an end cone (118b) that forms the free end of the clip-on mechanism (118).

6. The chronograph mechanism (10) according to claim 5, characterized in that the first support mechanism (111) on the first hammer (110) has a recess (117) for axially fixing the first bracket (116.1) on the elastic coupling mechanism (116) in an axial direction parallel to the at least one rotation axis (105) of the hammers (110, 120).

7. The chronograph mechanism (10) according to claim 6, characterized in that the recess (117) is formed near the base of the end cone (118b).

8. The chronograph mechanism (10) according to claim 1, wherein the second hammer (120) comprises a second support mechanism (112) configured to support the second bracket (116.2) of the elastic coupling mechanism (116), and the second support mechanism (112) has a recess for axially fixing the second bracket (116.2) on the elastic coupling mechanism (116) in an axial direction parallel to the at least one rotation axis (105) of the hammers (110, 120).

9. The chronograph mechanism (10) according to claim 1, further comprising a zero-reset control unit (60) which can be operated by a user and configured to rotate the first hammer (110).

10. The chronograph mechanism (10) according to claim 1, characterized in that the elastic coupling mechanism (116) is formed to elastically restrain the second hammer (120) when the second hammer (120) presses against the stopping surface (128) of the first hammer (110).

11. The chronograph mechanism (10) according to claim 10, characterized in that the second hammer (120) is pressed by the support surface (128) of the first hammer (110) by a stopping mechanism (122).

12. The chronograph mechanism (10) according to claim 1, characterized in that the first hammer (110) and the second hammer (120) have a shared axis of rotation (105) or separate axes of rotation parallel to each other.

13. A watch movement (1) comprising the chronograph mechanism (10) described in claim 1.

14. A timekeeping device comprising the clock movement (1) described in claim 13.

15. A method (400) for assembling a chronograph mechanism (10) equipped with a zero-reset mechanism (100), wherein the zero-reset mechanism (100) is A first hammer (110) and a second hammer (120) are configured in two levels to pivot around at least one axis of rotation (105) and engage with a first zero-reset mechanism (51) on a first chronograph counter and a second zero-reset mechanism (52) on a second chronograph counter, respectively, An elastic coupling mechanism (116) is positioned between the first hammer (110) and the second hammer (120) and configured to rotatably connect the first hammer (110) and the second hammer (120), The method comprises, Step (410) includes: The elastic coupling mechanism (116) is positioned on the second hammer (120), and the elastic coupling mechanism (116) is held in a pre-assembled position in a first compressed state between a pre-support mechanism (115) held by the second hammer (120) and a second support mechanism (112) on the second hammer (120); The first hammer (110) and the second hammer (120) are assembled by the relative axial displacement of the two hammers (110, 120) in a direction parallel to the at least one axis of rotation (105), and the relative axial displacement between the two hammers (110, 120) ensures an elastic connection between the two hammers (110, 120), step (420), A method (400) characterized by including the following.

16. The method (400) of claim 15, characterized in that the elastic coupling between the two hammers (110, 120) in step (420) is achieved by a clip-on mechanism (118), which is fixed to the first hammer (110), engages with the elastic coupling mechanism (116) in the pre-assembled position, and is configured to move the elastic coupling mechanism (116) to an operating position in a second compressed state in which the elastic coupling mechanism (116) is compressed between the clip-on mechanism (118) and the second support mechanism (112) on the second hammer (120).

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