Perpetual calendar mechanism with concentric cam

Abstract

The invention relates to a perpetual calendar mechanism for a watch movement, comprising a set of concentric cams (20) comprising a month cam (22) and a year cam (30). The mechanism further comprises: a rocker (50) having antennas (52) arranged to cooperate with the set of concentric cams (20); and a star wheel (70). The star wheel (70) is designed to be directly or indirectly actuated by the rocker (50) per day and to be further actuated on the last day of a month of less than 31 days depending on the angular position of the month cam (22) and the year cam (30) in order to catch up to the first day of the next month. The month cam (22) includes a radial opening (27) such that the feeler (52) of the rocker (50) may mate with one or the other of the month cam (22) and the year cam (30) depending on the angular position of the month cam (22).

Description

Technical Field

[0001] The invention relates to a perpetual calendar mechanism for a watch movement, comprising a month cam and a year cam concentrically nested in the month cam. The invention also relates to a timepiece, in particular a wristwatch, comprising a watch movement equipped with a perpetual calendar mechanism having concentric cams. Background Art

[0002] There are various mechanisms for indicating information related to the date. These mechanisms have a relatively simple structure for displaying the date without correction; there is an annual calendar type that can control the transition of the months with 30 days and 31 days to the first day of the next month; and there is a perpetual calendar type that includes a mechanical memory to a certain extent, not only enabling the control of the transition of the months with 30 days and 31 days to the first day of the next month, but also enabling the control of the transition from the end of February to the first day of March in consideration of the leap year.

[0003] Perpetual calendar mechanisms therefore generally have a complex and cumbersome construction, which may have a significant impact on the size of the case of a watch movement equipped with such a mechanism.

[0004] For example, EP3026504 discloses a perpetual calendar mechanism based on 48 cams, which include 48 notches, each associated with a month in a period of four consecutive years. The mechanism also includes a rocker including an angular tail intended to cooperate with the 48 notches.

[0005] EP3734373 discloses another example of a perpetual calendar mechanism. The mechanism comprises a month cam having an eccentric circular cutout in which a year cam is arranged. A large rocker is arranged to contact the profile of one or the other of the month cam and the year cam according to the respective angular position of each cam. Since the year cam is eccentric relative to the month cam, the perpetual calendar mechanism comprises a drive system capable not only of rotating the year cam about its axis at a speed of one revolution every four years, but also of driving the year cam and the month cam together in rotation about the center of the latter at a speed of one revolution per year.

[0006] This mechanism includes a drive system and therefore has the disadvantage that it is relatively complicated in order to impart two different movements to the year cam.

[0007] It is therefore an object of the present invention to provide a perpetual calendar mechanism which is at least free from the above-mentioned limitations.

[0008] More specifically, an object of the invention is to provide a compact perpetual calendar mechanism.

[0009] Another object of the invention is to provide a perpetual calendar mechanism that is simpler in construction, more robust and therefore more reliable.

[0010] An additional object of the invention is to provide a perpetual calendar mechanism comprising a drive system for the month and year cams that is simplified compared to the above mechanisms. Summary of the invention

[0011] These objects are achieved in particular by a perpetual calendar mechanism for a watch movement, comprising a set of concentric cams. The set comprises: a month cam arranged to be driven at a rate of one revolution per year; and a year cam arranged to be driven at a rate of one revolution every four years. The month cam comprises a central recess in which the year cam is located. The mechanism also comprises: a rocker with a feeler arranged to cooperate with the set of concentric cams; and a star wheel. The star wheel is arranged to be actuated directly or indirectly by the rocker every day and, depending on the angular position of the month cam and the year cam, is further actuated on the last day of a month with less than 31 days in order to achieve catch-up until it reaches a state corresponding to the first day of the next month. The month cam comprises a radial opening so that the feeler of the rocker can cooperate with the month cam or the year cam depending on the angular position of the month cam.

[0012] In one embodiment, the thickness of one of the month cam and the year cam is at least half the thickness of the other of the month cam and the year cam.

[0013] In one embodiment, at least 3 / 5, preferably at least 4 / 5, of the thickness of one of the month cam and the year cam is at the level of the thickness of the other of the month cam and the year cam.

[0014] In one embodiment, the top side of the month cam is substantially coplanar with the top side of the year cam.

[0015] In one embodiment, the bottom side of the month cam is substantially coplanar with the bottom side of the year cam.

[0016] In one embodiment, the central recess of the month cam comprises a cylindrical wall arranged to abut against at least a portion of the profile of the year cam so that said year cam can guide the month cam in rotation.

[0017] In one embodiment, the year cam is fixed to a large wheel meshing with at least one wheel arranged to be driven once a month by a star wheel. The month cam is arranged to be driven by a gear train comprising a first wheel fixed to the month cam and mounted coaxially therewith, a second wheel meshing with the first wheel and an intermediate wheel fixed to the second wheel and meshing with the teeth of the large wheel.

[0018] In one embodiment, the feeler of the rocker is arranged between the first wheel and the large wheel.

[0019] In one embodiment, the first wheel and the month cam form together a single part.

[0020] In one embodiment, the large wheel and the year cam are formed together as a single part.

[0021] In one embodiment, the profile of the year cam comprises three radial notches corresponding to the February sector of the cam in a non-leap year.

[0022] In one embodiment, the mechanism also includes a 24H wheel arranged to be driven at a speed of one revolution in 24 hours, and a 24H finger fixed to the 24H wheel. The rocker itself includes a first beak arranged to cooperate with the 24H finger, and a second beak arranged to actuate the rotation of a 31 star wheel typically fixed to the date indication of the month.

[0023] In one embodiment, the mechanism further comprises a wheel and a pusher dog fixed to the wheel. The rocker comprises a rake meshed with the wheel so that each time the rocker is actuated by the 24H pusher dog, the pusher dog is meshed with the 31 star wheel. In this way, the 31 star wheel can be rotated one step per day.

[0024] Other aspects of the invention relate on the one hand to a watch movement equipped with a calendar mechanism with concentric cams according to the invention, and on the other hand to a timepiece, in particular a wristwatch, comprising a watch movement equipped with a calendar mechanism with concentric cams according to the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Examples of embodiments of the invention are given in the description illustrated in the accompanying drawings, in which: - Figure 1 shows a top view of a perpetual calendar mechanism with concentric cams according to an embodiment; - Figure 2 Shows the arrangement with Figure 1 A top view of a rocker lever matched with a set of concentric cams of the mechanism; - Figure 3 Shows Figure 2 A cross-sectional view of the set of concentric cams and feelers; - Figure 4 Shows Figure 2 An exploded view of the set of concentric cams; - Figure 5 A perspective view of the month cam seen from below is shown; - Figure 6 Shows Figure 5 Bottom view of the month cam; - Figure 7 Shows Figure 4 A top view of the large wheel and year cam of the set of concentric cams; - Figure 1 and Figures 8a to 8dShows the transition from the last day of February to the first day of March during a non-leap year. Figure 1 A top view of an example of the operating sequence of the perpetual calendar mechanism; - Figure 9a and 9b Shows the transition from the last day of February to the first day of March during a leap year. Figure 1 A top view of an example of the operating sequence of the perpetual calendar mechanism, and - Figures 10a to 10d shows the transition from the 30th day of April to the first day of May Figure 1 A top view of an example of the operating sequence of the perpetual calendar mechanism. DETAILED DESCRIPTION

[0026] In a preferred embodiment, and in particular with reference to Figures 1 to 7 The perpetual calendar mechanism 10 includes a set of concentric cams 20 and a rocker 50, which is arranged to cooperate with the set of concentric cams 20 and actuate 31 the star wheel 70 according to the information given by the set of concentric cams 20. The set 20 includes a month cam 22 (commonly called a 12-month cam) and a year cam 30, which are coaxially mounted.

[0027] To this end, the month cam 22 comprises a central recess 28 defined by a cylindrical wall 28a and a radial opening 27 extending from the edge of the cam profile and opening into the central recess 28, as shown in FIG. Figure 5 and Figure 6 The year cam 30 is arranged in the central recess 28 of the month cam. Preferably, the central recess 28 consists of a through hole formed in the month cam 22. Also preferably, the opening is substantially circular in shape and will allow the year cam 30 to pass through the month cam 22.

[0028] according to Figure 6 and Figure 7 The month cam includes four sectors 25a corresponding to the months of 30 days in a year, and seven sectors 25b corresponding to the months of 31 days in a year, wherein two pairs of sectors corresponding to the paired months of July to August and December to January are each formed by adjacent sectors 25b. The sectors 25a and 25b and the radial opening 27 representing February are arranged in sequence to indicate the different months of a year in chronological order.

[0029] Thus, radial opening 27 borders two sectors 25b, corresponding to January and March. Sectors 25a and 25b are typically circular sectors whose distal edges define an arc having the same center. As described in detail below, radial opening 27 enables rocker 50 to obtain information from the year cam in order to adjust star wheel 70 at the end of February depending on whether the year is a non-leap year or a leap year.

[0030] refer to Figure 7 The profile of the year cam 30 includes three radial notches 34a spaced 90° apart from each other. These three notches are used to correct the date display at the end of February in a non-leap year. The profile of the year cam 30 also includes a sector 34b extending between two radial notches 34a that are substantially diametrically opposite. The sector 34b is used to correct the date display at the end of February in a leap year.

[0031] Preferably, the top and bottom sides of the month cam 22 and the year cam 30 are flat and perpendicular to the common axis of rotation of these cams. Figure 3 , the top side 23a of the month cam 22 is substantially coplanar with the top side 32a of the year cam 30, i.e. the misalignment between the respective top sides of the two cams does not exceed 20%, preferably 10%, of the thickness of one of the cams. The same applies to the respective bottom sides 23b, 32b of the month cam 22 and the year cam 30. Thus, the year cam 30 is preferably integrally nested in the month cam 22, wherein the cam profile of constant diameter rests on the cylindrical wall 28a of the central recess 28, so that the month cam can thereby be guided in rotation by the year cam.

[0032] However, in an embodiment not shown, the thickness of the month cam may be significantly different from the thickness of the year cam. The thickness of the month cam 22 may be much smaller than the thickness of the year cam 30, and may be, for example, half the thickness of the year cam. The opposite is also possible, i.e. the thickness of the year cam 30 may be much smaller than the thickness of the month cam 22, for example half the thickness of the latter.

[0033] Advantageously, the cylindrical wall 28a defining the central recess 28 of the month cam 22 is arranged against the cam profile of constant diameter of the year cam 30. Preferably, this arrangement is made with just enough clearance so that one of the cams 22, 30 does not drag the other due to friction. Thus, the year cam can rotate at a speed of one revolution every four years, while guiding the month cam 22 to rotate around its profile at a speed of one revolution per year. Thus, the month cam 22 and the year cam 30 remain unconnected and rotate at different speeds.

[0034] Special References Figure 4 , the year cam 30 is connected to a large wheel 36. This wheel is typically meshed with a gear train, which preferably includes such Figure 1 The first and second wheels 37, 38 shown in FIG. The first wheel 37 is arranged to be driven once a month by a driving finger 76 attached to a star wheel 70. This star wheel is fixed on a display (not shown) comprising the numbers 1 to 31 so that they can be successively displayed, for example through a dial hole. The gear train 37, 38 allows the large wheel 36 to be driven to rotate a full circle every four years to drive the year cam 30 so that the latter also rotates a full circle every four years.

[0035] Large wheel 36 and year cam 30 are made in a single part, but they can also be made separately and fixed against each other. Month cam 22 itself is arranged to be driven by a gear train comprising a first wheel 42 connected to month cam 22 and mounted coaxially therewith, a second wheel 44 meshing with first wheel 42, and an intermediate wheel 46 connected to second wheel 44 and meshing with the teeth of large wheel 36. Like large wheel 36 and year cam 30, month cam 22 and first wheel 42 are made in a single part, but they can also be made separately and fixed against each other.

[0036] according to Figure 1 The second wheel 44 has twelve teeth and cooperates with a jumper spring 47 so as to drive the month cam 22 to rotate at a speed of 30° (one twelfth of a turn) per month through the second wheel 44, and the jumper spring 47 allows the jump to be completed. The perpetual calendar mechanism 10 also includes a 24H wheel 80, which is arranged to be driven at a speed of one turn per day. The 24H finger 82 is fixed to the 24H wheel 80 to actuate the rocker 50, which in turn rotates the wheel 62, which meshes with the rake 58 connected to the rocker 50, so as to rotate the star wheel 70 through the finger 66 connected to the wheel 62, so that the star wheel 70 jumps once a day. In addition, if necessary, adjustments are made at the end of the month depending on the angular position of the month cam 22 and the year cam 30.

[0037] refer to Figure 2 To this end, rocker 50 comprises a feeler 52 arranged to cooperate with the profile of one or the other of the month cam and the year cam, depending on the respective angular position of the respective cam. In particular, feeler 52 is arranged to abut against the profile of one of the aforementioned cams. Since these different profiles are located at different radial distances from the common rotation center of cams 22 and 30, these different profiles allow the amplitude of movement of rocker 50 to vary when it is actuated by 24H finger 82.

[0038] The feeler 52 is arranged between the first wheel 42 and the large wheel 36. Figure 3 According to this illustration, radial opening 27 of month cam 22 is positioned facing feeler 52 so that it can be introduced into this opening to come into contact with the profile of year cam 30 in order to be able to make the necessary corrections at the end of February to take into account leap years.

[0039] Rocker 50 also comprises a first beak 54 located on the trajectory of 24H finger 82, and a second beak 56 arranged to actuate star wheel 70 via a catch finger 72 connected to star wheel 70, the latter cooperating with a jumper spring 74, as shown in FIG. Figure 1It should be noted that the capture finger 72 is mounted on a leaf spring 73 arranged to bend against the capture finger 72 under the action of the second beak 56 of the rocker so that the rocker 50 is not blocked by the finger when the feeler 52 falls back against the set of concentric cams 20.

[0040] A rocker spring 60 (for example in the form of a spiral) is fixed to the wheel 62 so as to push the latter into the Figure 1 The arrangement (in particular comprising rake 58, wheel 62 and rocker spring 60) enables the feeler 52 of rocker 50 to be pushed against the profile of one or the other of month cam 22 and year cam 30 when the rocker is stationary. Pusher 66 is fixed to wheel 62 so as to actuate star wheel 70 to jump once a day (i.e. one step). It should be noted that Figure 1 Shows the status of the institution on the 28th day of February in a non-leap year.

[0041] Since the catching finger 72 is fixed to the star wheel 70, the finger rotates once a month. The finger is separated from the track of the second beak 56 of the rocker 50 throughout the month, so that the rocker actuates the star wheel 70 only through the finger 66 every day, thereby ensuring the transition from the indication of one day to the indication of the next day. At the end of each month with less than 31 days, the catching finger 72 is located on the track of the second beak 56 of the rocker 50, as shown in FIG. Figure 1 Specifically shown in.

[0042] When the 24H finger actuates the rocker 50 again, the rocker 50 will drive the star wheel 70 through the action of the second beak 56 on the catching finger 72 according to the movement amplitude of the rocker 50 (which is directly related to the angular position of each of the month cam 22 and the year cam 30), so that the star wheel 70 can make one or more additional jumps to catch up at night from the last day of the month with less than 31 days to the first day of the next month.

[0043] The use of a year cam nested in the month cam, instead of the traditional 48 cams, advantageously enables a larger and therefore more robust feeler. This makes the perpetual calendar mechanism more reliable and less susceptible to machining defects. It also makes the mechanism easier to assemble and adjust.

[0044] Now refer to Figure 1 and Figures 8a to 10d The operation of the perpetual calendar mechanism 10 will be described.

[0045] Figure 1 and 8a 8d represents the running order of the end of February in a non-leap year. As mentioned above, Figure 1The mechanism state on the 28th day of February in a non-leap year is shown. At this time, the side edge of a portion of the feeler 52 abuts against the edge of the radial opening 27 of the month cam. The distal end portion of the feeler 52 is located in one of the notches 34a of the year cam 30 ( Figure 7 ).

[0046] Figure 8a The mechanism is shown when the 24H finger 82 contacts the first beak 54 of the rocker 50 and pushes the latter to disengage the feeler 52 from the radial notch 34a of the year cam. The second beak 56 of the rocker 50 in turn pushes the catching finger 72 of the 31 star wheel, which starts the rotation of the latter.

[0047] exist Figure 8a and 8b The movement of the second beak 56 shown between the illustrations enables the star wheel 70 to rotate by catching the finger 72, causing the star wheel to perform three consecutive jumps. Therefore, the amplitude of the movement of the rocker 50 is at its maximum during this period. As the rocker 50 moves, its rake rotates the wheel 62, which gradually pivots the finger 66 until it moves the star wheel 70 one step, as shown in FIG. Figure 8c and 8d Thus, in the night between the 28th day of February and the 1st day of March in a non-leap year, the second beak 56 of the rocker 50 activates the star wheel 70, causing the star wheel 70 to make three consecutive jumps, and then the finger 66 activates the star wheel, causing the star wheel to make an additional jump.

[0048] refer to Figure 8c It should be noted that the actuation of star wheel 70 at the end of the month enables first wheel 37 to be driven via drive finger 76. The first wheel drives large wheel 36 via second wheel 38, causing the latter to rotate by one forty-eighth of a turn. This rotation also drives year cam 30 by one forty-eighth of a turn, and month cam 22 by one twelfth of a turn, via the gear train comprising first and second wheels 42, 44 and intermediate wheel 46. Sector 25 of the month cam corresponding to a month of 31 days (in this case March) is therefore in the trajectory of feeler 52 of the rocker, as shown in FIG. Figure 8d As soon as the 24H pusher 82 is disengaged from the first beak 54 of the rocker, the feeler 52 will return to the position against the sector 25b under the effect of the coil spring 60.

[0049] From the first day of March, throughout the month, the catch finger 72 is out of the track of the beak 56 of the rocker 50, so that the rocker 50 actuates the star wheel 70 only through the finger 66 every day, thus ensuring the transition from the indication of one day to the indication of the next day. The contact of the feeler 52 of the rocker against the sector 25b of the month cam enables the rocker 50 to be positioned so that the second beak 56 is out of the track of the catch finger 72, in particular at the end of the month, during its passage through March 30-31. Therefore, no correction is required for this month. The same applies to all months with 31 days like March.

[0050] Figure 9a and 9b The running sequence at the end of February in a leap year is shown. Figure 9a The mechanism is shown on the 29th day. The feeler 52 of the rocker 50 is now arranged to abut against the sector 34b of the profile of the year cam. During the night from the 29th day to the 1st day of March, the 24H finger 82 exerts a thrust on the first beak 54 of the rocker 50, driving the latter until the second beak 56 in turn exerts a thrust on the catch finger 72 of the star wheel 70 ( Figure 9b ), so that the latter jumps twice in succession. Then, finger 66 actuates star wheel 70 as described above, and star wheel 70 makes an additional jump to change the indication from the 29th to the 1st of March.

[0051] Figures 10a to 10d The running order for the end of April is shown. Fig.10a The mechanism is shown for the 30th day of April. At this time, the feeler 52 of the rocker 50 is arranged to abut against the sector 25a of the profile of the month cam. The 24H finger 82 exerts a thrust on the first beak 54 of the rocker 50, as shown in FIG. Fig.10b Then the second beak 56 of the rocker drives the star wheel 70 by catching the pusher 72, as shown in FIG. Fig.10c , so that the star wheel jumps under the action of finger 66 and then makes an additional jump, the action of the rocker's rake on wheel 62 causing finger 66 to pivot.

[0052] from Fig.10b It can be seen that the actuation of the star wheel 70 at the end of the month enables the first wheel 37 to be driven by the driving finger 76. As described above, the gear trains 37, 38 connecting the star wheel 70 and the large wheel 36 and the gear trains 44, 46 connecting the large wheel 36 and the first wheel 42 enable the month cam to be driven by one twelfth of a turn. Therefore, the sector 25b of the month cam corresponding to the month with 31 days (in this case, May) is on the trajectory of the feeler 52 of the rocker.

[0053] according to Fig.10d Once the 24H pusher finger 82 is disengaged from the first beak 54 of the rocker, the contact 52 abuts against the sector 25 b under the action of the coil spring 60 .

[0054] The order of operation described above for April remains the same for other months of the year that also have 30 days like April.

[0055] Various modifications may be made to the calendar mechanism just described without departing from the invention as defined in the claims. For example, rocker 50 may be shaped so as to directly actuate 31 star wheel per day, so that the latter may perform a single jump, in particular independently of the amplitude of the movement of the rocker, which would make it possible, for example, to eliminate the need for finger 66. According to another variant, the rocker may be replaced by a conventional large rocker comprising a large pawl cooperating with cam 31 fixed to 31 star wheel, instead of capturing the finger. Reference Numbers List Perpetual calendar mechanism 10 A set of concentric cams 20 Cam of the Month 22 Top side 23a Bottom side 23b 30-day month sector 25a 31-day month sector 25b Radial opening 27 Center recess 28 Cylindrical wall 28a Year Cam 30 Top side 32a Bottom side 32b Radial notch 34a Sector 34b Big Wheel 36 Gear Train First and second round 42, 44 Intermediate wheel 46 Jumping spring 47 Gear Train First and second round 37, 38 Rocker 50 Tentacle 52 First Beak 54 Second Beak 56 Rake 58 Rocker spring 60 (eg, spiral) Wheel 62 Claw 66 31 Star Wheel 70 Capture claw 72 Leaf spring 73 Jumping spring 74 Driving finger 76 24H round 80 24H finger 82.

Claims

1. A perpetual calendar mechanism (10) for a watch movement, comprising: A set of concentric cams (20) comprising: a month cam (22) comprising a central recess (28) and arranged to be driven at a rate of one revolution per year; and a year cam (30) located in the central recess (28) of the month cam (22) and arranged to be driven at a rate of one revolution every four years, a rocker (50) comprising a feeler (52) arranged to cooperate with the set of concentric cams (20), and a star wheel (70) arranged to be actuated daily directly or indirectly by the rocker (50) and further actuated on the last day of a month with fewer than 31 days, depending on the angular positions of the month cam (22) and the year cam (30), in order to achieve catch-up, in The month cam (22) comprises a radial opening (27) so that the feeler (52) of the rocker (50) can cooperate with one or the other of the month cam (22) and the year cam (30) depending on the angular position of the month cam (22).

2. The mechanism (10) according to claim 1, wherein: The thickness of one of the month cam (22) and the year cam (30) is at least half the thickness of the other of the month cam (22) and the year cam (30).

3. The mechanism (10) according to any one of the preceding claims, wherein: At least 3 / 5, preferably at least 4 / 5, of the thickness of one of the month cam (22) and the year cam (30) is at the same level as the thickness of the other of the month cam (22) and the year cam (30).

4. The mechanism (10) according to any one of the preceding claims, wherein: The top side (23a) of the month cam (22) is substantially coplanar with the top side (32a) of the year cam (30).

5. The mechanism (10) according to any one of the preceding claims, wherein: The bottom side (23b) of the month cam (22) is substantially coplanar with the bottom side (32b) of the year cam (30).

6. The mechanism (10) according to any one of the preceding claims, wherein: The central recess (28) of the month cam (22) comprises a cylindrical wall (28a) arranged to abut against at least a portion of the profile of the year cam (30) so that the year cam can guide the month cam in rotation.

7. The mechanism (10) according to any one of the preceding claims, wherein: The year cam (30) is fixed to a large wheel (36) which meshes with at least one wheel (37, 38) arranged to be driven once a month by the star wheel (70), and wherein the month cam (30) is arranged to be driven by a gear train comprising a first wheel (42) fixed to the month cam (12) and mounted coaxially therewith, a second wheel (44) meshing with the first wheel (42) and an intermediate wheel (46) fixed to the second wheel (44) and meshing with the teeth of the large wheel (36).

8. The mechanism (10) according to the preceding claim, wherein: The feeler (52) of the rocker (50) is arranged between the first wheel (42) and the large wheel (36).

9. The mechanism according to claim 7 or 8, wherein: The first wheel (42) and the month cam (22) form together a single part.

10. The mechanism according to any one of claims 7 to 9, wherein: The large wheel (36) and the year cam (30) together form a single part.

11. The mechanism (10) according to any one of the preceding claims, wherein: The profile of the year cam (30) comprises three radial notches (34a) corresponding to the non-leap year sectors of the cam.

12. The mechanism (10) according to any one of the preceding claims, further comprising: a 24H wheel (80) arranged to be driven at a speed of one revolution in 24 hours; and a 24H pusher claw (82) fixed to the 24H wheel (80); the rocker (50) comprises: a first beak (54) arranged to cooperate with the 24H pusher claw (82); and a second beak (56) arranged to actuate the star wheel (70) in rotation via a capture finger (72) fixed to the star wheel.

13. The mechanism (10) according to the preceding claim, further comprising a wheel (62) and a pusher dog (66) fixed to the wheel (62), said rocker (50) comprising a rake (58) meshing with said wheel (62) so as to bring said pusher dog (66) into engagement with said star wheel (70) each time said rocker is actuated by said 24H pusher dog (80).

14. A watch movement comprising a mechanism according to any one of the preceding claims.

15. A timepiece, in particular a wristwatch, comprising a watch movement according to the preceding claim.

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