MECHANISM OF A PERPETRAL CALENDAR WITH CONCENTRICAL CAMS

Description

technical field

[0001] The present invention relates to a perpetual calendar mechanism for a watch movement, comprising a month cam and a year cam concentrically nested within the month cam. The invention also relates to a timepiece, in particular a wristwatch, comprising a watch movement equipped with the concentric cam perpetual calendar mechanism. State of the art

[0002] There are different mechanisms for indicating date information. These mechanisms are of relatively simple construction for displaying the date without correction, of the annual calendar type capable of managing the transition from 30- and 31-day months on the 1st of the following month, and of the perpetual calendar type which has a mechanical memory, so to speak, allowing not only the transition from 30- and 31-day months on the 1st of the following month, but also the transition from the end of February to the 1st of March, taking into account leap years.

[0003] Perpetual calendar mechanisms therefore most often have a complex and bulky construction, which can have a significant impact on the size of the watch case incorporating a watch movement equipped with such a mechanism.

[0004] As an example, EP3026504 discloses a perpetual calendar mechanism based on a 48-inch cam comprising 48 notches, each associated with a month over a period of four consecutive years. This mechanism further includes a rocker with a probing tail designed to engage with these 48 notches.

[0005] EP3734373 discloses another example of a perpetual calendar mechanism. This one features a month cam with an off-center circular cutout in which a year cam is mounted. A large rocker is arranged to contact the profile of either the month or year cam, depending on the respective angular position of each cam. Because the year cam is off-center relative to the month cam, the perpetual calendar mechanism includes a drive system capable not only of rotating the year cam around its axis once every four years, but also of driving the year cam and month cam together around the center of the latter once per year.

[0006] This mechanism includes a drive system which consequently has the disadvantage of being relatively complex in order to impart two distinct movements to the years cam.

[0007] One aim of the present invention is therefore to propose a perpetual calendar mechanism at least free from the aforementioned limitations.

[0008] More specifically, one aim of the present invention is to provide a compact perpetual calendar mechanism.

[0009] Another aim of the present invention is to propose a perpetual calendar mechanism of simpler construction, more robust and therefore more reliable.

[0010] An additional object of the present invention is to propose a perpetual calendar mechanism comprising a drive system for the month and year cams which is simplified compared to the mechanisms mentioned above. Brief summary of the invention

[0011] These goals are achieved in particular by a perpetual calendar mechanism for a watch movement, comprising a concentric cam assembly. This assembly includes a month cam arranged to rotate once per year, and a year cam arranged to rotate once every four years. The month cam has a central housing in which the year cam is positioned. The mechanism further includes a rocker arm with a feeler arranged to cooperate with the concentric cam assembly, as well as a star wheel. This star wheel is arranged to be actuated daily, either directly or indirectly, by the rocker arm, and also to be actuated on the last day of months with fewer than 31 days, depending on the angular position of the month and year cams, in order to adjust the time to a state corresponding to the first day of the following month.The month cam has a radial opening so that the rocker feeler can cooperate with either the month cam or the year cam depending on the angular position of the month cam.

[0012] According to one embodiment, the thickness of one of the month cams and year cams is at least half the thickness of the other of the month cams and year cams.

[0013] According to one embodiment, at least 3 / 5, preferably at least 4 / 5 of the thickness of one of the month cams and the year cams is at the same level as the thickness of the other of the month cams and the year cams.

[0014] According to one embodiment, the upper face of the month cam is substantially coplanar with the upper face of the year cam.

[0015] According to one embodiment, the lower face of the month cam is substantially coplanar with the lower face of the year cam.

[0016] According to one embodiment, the central housing of the month cam has a cylindrical wall arranged against at least part of the profile of the year cam so that the year cam can guide the month cam in rotation.

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

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

[0019] According to one embodiment, the first wheel and the month cam together form a single piece.

[0020] According to one form of realization, the large wheel and the cam of the years together form a single piece.

[0021] According to one embodiment, the profile of the year cam has three radial notches corresponding to the sectors of the month of February of non-leap years of the cam.

[0022] In one embodiment, the mechanism further comprises a 24-hour wheel arranged to rotate once every 24 hours and a 24-hour finger attached to the 24-hour wheel. The rocker itself comprises a first beak arranged to cooperate with a 24-hour finger and a second beak arranged to rotate the 31-hour star, typically attached to the day-of-the-month indicators.

[0023] In one embodiment, the mechanism further comprises a wheel and a finger attached to the wheel. The rocker arm includes a rake that engages with the wheel to lock the finger to the 31-point star wheel each time the rocker arm is operated by the 24-hour finger. In this way, the 31-point 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 the concentric cam date mechanism according to the invention, and on the other hand to a timepiece, in particular a wristwatch, comprising a watch movement equipped with the concentric cam date mechanism according to the invention. Brief description of the figures

[0025] Examples of implementation of the invention are shown in the description illustrated by the accompanying figures, in which: there figure 1illustrates a top view of a perpetual calendar mechanism with concentric cams in one embodiment; the figure 2 illustrates a top view of a rocker arm arranged to cooperate with a concentric cam assembly of the mechanism of the figure 1 ; there figure 3 illustrates a cross-sectional view of the concentric cam assembly and the probe of the figure 2 ; there figure 4 illustrates an exploded view of the concentric cam assembly of the figure 2 ; there figure 5 illustrates a perspective view from below of the month's cam; the figure 6 illustrates a bottom view of the cam from the months of the figure 5 ; there figure 7 illustrates a top view of the large wheel and cam from the years of the concentric cam assembly of the figure 4 ; THE Figures 1 And 8a to 8d illustrate top views of an example of an operational sequence of the perpetual calendar mechanism of the figure 1during the transition from the last day of February to the first day of March in a non-leap year; figures 9a And 9b illustrate top views of an example of an operational sequence of the perpetual calendar mechanism of the figure 1 during the transition from the last day of February to the first day of March in a leap year, and the figures 10a to 10d illustrate top views of an example of an operational sequence of the perpetual calendar mechanism of the figure 1 during the transition from the 30th day of April to the first day of May. Examples of embodiments of the invention

[0026] According to a preferred form and with reference in particular to figures 1 to 7The perpetual calendar mechanism 10 comprises a concentric cam assembly 20 and a rocker 50 arranged to cooperate with the concentric cam assembly 20 and to actuate a star of 31 - 70 according to the information given by the concentric cam assembly 20. This assembly 20 includes a month cam 22, commonly called the 12 cam, and a year cam 30 which are mounted coaxially.

[0027] The cam of months 22 comprises for this purpose a central housing 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 housing 28 as illustrated in particular by the figures 5 and 6The 30s cam is arranged inside the central housing 28 of the month cam. Preferably, this central housing 28 consists of a through opening formed in the month cam 22. Even more preferably, this opening is essentially circular in shape and would allow the passage of the 30s cam through the month cam 22.

[0028] According to the figures 6 And 7 The month cam comprises four sectors 25a corresponding to the 30-day months of the year, and seven sectors 25b corresponding to the 31-day months of the year. Two pairs of sectors, corresponding to the July-August and December-January pairs, are each formed of contiguous 25b sectors. Sectors 25a and 25b, as well as the radial opening 27 representing the month of February, are arranged successively to represent, in chronological order, the different months of the year.

[0029] Thus, the radial aperture 27 is bordered by two sectors 25b corresponding to the months of January and March. Sectors 25a and 25b are typically circular sectors whose distal edges define arcs of circles with the same center. As described in detail below, the radial aperture 27 allows the flip-flop 50 to retrieve the year information from the cam in order to perform an adjustment on the star 70 at the end of February, depending on whether it is a non-leap year or a leap year.

[0030] With reference to the figure 7The cam profile from the 1930s features three radial notches 34a spaced 90° apart. These three notches allow for correcting the date display at the end of February in a non-leap year. The cam profile from the 1930s also includes a sector 34b extending between two radial notches 34a that are substantially diametrically opposite. Sector 34b allows for correcting the date display at the end of February in a leap year.

[0031] Preferably, the upper and lower faces of the 22-month and 30-year cams are flat and perpendicular to the common axis of rotation of these cams. Referring to the figure 3The upper face 23a of the month cam 22 is substantially coplanar with the upper face 32a of the year cam 30, meaning that the offset between the respective upper faces of the two cams does not exceed 20%, preferably 10%, of the thickness of either cam. The same applies to the respective lower faces 23b and 32b of the month cam 22 and the year cam 30. Consequently, the year cam 30 is preferably fully nested within the month cam 22, with its constant-diameter cam profile positioned against the cylindrical wall 28a of the central housing 28, so that the month cam can be guided in rotation by the year cam.

[0032] The thickness of the month cam can, however, differ significantly from the thickness of the year cam depending on the specific design variations not shown. The thickness of the month 22 cam can be considerably less than the thickness of the year 30 cam, for example, half the thickness of the year cam. Conversely, the thickness of the year 30 cam can be considerably less than the thickness of the month 22 cam, for example, half the thickness of the latter.

[0033] Advantageously, the cylindrical wall 28a defining the central housing 28 of the month cam 22 is arranged against the constant-diameter cam profile of the year cam 30. Preferably, this arrangement is set with just enough clearance so that neither cam 22, 30, drives the other by friction. The year cam can thus be driven in rotation at a rate of one revolution every four years while simultaneously guiding the rotation of the month cam 22 around its profile at a rate of one revolution per year. The month cam 22 and the year cam 30 therefore remain independent and rotate at different speeds.

[0034] With particular reference to the figure 4 The cam from the 1930s is attached to a large wheel 36. This is typically engaged with a gear train preferably comprising a first and a second wheel 37, 38 as illustrated in the figure 1The first wheel 37 is arranged to be driven once a month by the passage of a drive finger 76 attached to the star 70. This star is attached to a display (not shown) bearing the numbers 1 to 31 so that they can be scrolled successively, for example, through a window on a clock face. The gear train 37, 38 drives the large wheel 36 through a complete revolution every four years, which in turn drives the 1930 cam so that it also completes a full revolution every four years.

[0035] The large wheel 36 and the 1930s cam are made in one piece but could just as easily be made separately and fixed together. The 22 months cam is arranged to be driven by a gear train comprising a first wheel 42 integral with the 22 months cam and mounted coaxially to it, a second wheel 44 meshing with the first wheel 42, and a drive 46 integral with the second wheel 44 and meshing with the teeth of the large wheel 36. Like the large wheel 36 and the 1930s cam, the 22 months cam and the first wheel 42 are made in one piece but could just as easily be made separately and fixed together.

[0036] According to the figure 1The second wheel 44 has twelve teeth and cooperates with a jumper 47 to drive the month cam 22 by the second wheel 44, rotating it by a jump of 30° (one-twelfth of a turn) every month. The jumper 47 completes the jump. The perpetual calendar mechanism 10 also includes a 24-hour wheel 80 arranged to rotate once a day. A 24-hour finger 82 is fixed to the 24-hour wheel 80 to actuate the rocker 50, which in turn rotates the wheel 62. This wheel is meshed with a rake 58 attached to the rocker 50, which in turn rotates the star 70 via the finger 66 attached to the wheel 62, so that the star 70 completes one jump each day. Furthermore, where necessary, a catch-up at the end of the month is carried out based on the angular position of the cam for months 22 and the cam for years 30.

[0037] With reference to the figure 2The rocker 50 includes for this purpose a feeler 52 arranged to cooperate with the profile of either the month cam or the year cam, depending on the respective angular position of each cam. In particular, the feeler 52 is arranged to bear against the profile of one of the aforementioned cams. Being located at different radial distances from the common center of rotation of the cams 22 and 30, these different profiles allow the amplitude of the rocker 50's movement to be varied when it is actuated by the 24H finger 82.

[0038] The feeler 52 is arranged between the first wheel 42 and the large wheel 36 as illustrated in the figure 3According to this illustration, the radial opening 27 of the month 22 cam is positioned opposite the feeler 52 so that the feeler can be inserted into this opening to come into contact with the profile of the year 30 cam in order to make the necessary correction at the end of February taking into account leap years.

[0039] The rocker 50 also includes a first beak 54 positioned on the trajectory of the 24H finger 82 and a second beak 56 arranged to actuate the star 70 by means of a catching finger 72 attached to the star 70, which cooperates with a jumper 74 as shown in the figure 1 It should be noted that the adjusting finger 72 is mounted on a spring blade 73 arranged to flex under the action of the second beak 56 of the rocker against the adjusting finger 72 so that the rocker 50 is not blocked by this finger when the feeler 52 falls back against the concentric cam assembly 20.

[0040] A rocker spring 60, for example in the form of a spiral, is fixed to the wheel 62 in order to constrain the latter in the angular position illustrated in the figure 1 This arrangement, including the rake 58, the wheel 62, and the rocker spring 60, allows the feeler 52 of the rocker 50 to be pressed against the profile of either the month cam 22 or the year cam 30 when the rocker is at rest. A finger 66 is attached to the wheel 62 so that the star 70 can be actuated daily by one jump, that is, one step. It should be noted that the figure 1 illustrates the state of the mechanism on the 28th day of February in a non-leap year.

[0041] Since the compensating finger 72 is fixed to the star 70, it therefore rotates every month. This finger is clear of the path of the second beak 56 of the rocker 50 throughout the month so that the rocker 50 actuates the star 70 each day solely via the finger 66, thus ensuring the transition from one day's indication to the next. At the end of each month of fewer than 31 days, the compensating finger 72 comes to rest on the path of the second beak 56 of the rocker 50, as illustrated in particular in the figure 1 .

[0042] When the 24H finger again activates the rocker 50, the latter will drive the star 70 by the action of the second beak 56 on the catching finger 72 according to the amplitude of the displacement of the rocker 50, directly linked to the angular position of each of the month and year cams 22, 30, so that the star 70 can make one or more additional jumps to make a catch-up in the night of the last day of a month of less than 31 days to the first day of a following month.

[0043] Using a year cam nested within a month cam, instead of a conventional 48mm cam, allows for a larger and therefore more robust feeler. This results in a more reliable perpetual calendar mechanism that is less susceptible to machining defects. Furthermore, the assembly and adjustment of the mechanism are simplified.

[0044] The operation of the perpetual calendar mechanism 10 will now be described with reference to Figures 1 And 8a to 10d .

[0045] THE Figures 1 And 8a to 8d represent an operational sequence at the end of February in a non-leap year. As mentioned above, the figure 1 illustrates the state of the mechanism on the 28th day of February in a non-leap year. At this moment, the lateral edges of a portion of the feeler 52 are against the edges of the radial opening 27 of the month cam. The distal part of the feeler 52 is, for its part, inside one of the notches 34a of the year cam 30 ( figure 7 ).

[0046] There figure 8aThis illustrates the mechanism when the 24H finger 82 comes into contact with the first beak 54 of the rocker 50 and exerts a force on the latter in order to disengage the feeler 52 from the radial notch 34a of the year cam. The second beak 56 of the rocker 50 in turn exerts a force on the compensating finger 72 of the star 31, which initiates the rotation of the latter.

[0047] The movement of the second beak 56, illustrated between the representations of the figures 8a And 8b This allows the star 70 to be rotated, via the catching finger 72, so that it makes three successive jumps. The amplitude of the movement of the rocker 50 is therefore at its maximum during this period. During the movement of the rocker 50, its rake rotates the wheel 62, which progressively pivots the finger 66 until it actuates the star 70 by one step as shown in the diagram. figures 8c And 8d. Thus, on the night of February 28 to March 1 of a non-leap year, the second beak 56 of the rocker 50 activates the star 70 so that it makes three successive jumps, then the finger 66 activates the star so that it makes an additional jump.

[0048] We will note, by referring to the figure 8cthat the actuation of the star 70 at the end of this month drives the first wheel 37 via the drive finger 76. The first wheel, via the second 38, drives the large wheel 36, causing it to rotate one forty-eighth of a turn. This rotation drives the year cam 30 by one forty-eighth of a turn as well, and the month cam 22 by one twelfth of a turn via the gear train comprising the first and second wheels 42, 44 and the gearbox 46. A sector 25b of the month cam, corresponding to a month of 31 days, in this case March, is thus located on the path of the feeler 52 of the rocker, as can be seen on the figure 8d . Once the 24H finger 82 is freed from the first beak 54 of the rocker, the feeler 52 is brought back against the sector 25b under the action of the spiral spring 60.

[0049] From March 1st, the compensating finger 72 is clear of the path of the beak 56 of the rocker 50 throughout the month so that the rocker 50 actuates the star 70 each day solely via the finger 66, thus ensuring the transition from one day's indication to the next. The contact of the rocker's feeler 52 against sector 25b of the month cam positions the rocker 50 so that the second beak 56 is clear of the path of the compensating finger 72, particularly at the end of the month during its passage between March 30th and 31st. No correction is therefore made for this month. The same applies to all months that, like March, have 31 days.

[0050] THE figures 9a And 9b illustrate an operational sequence at the end of February in a leap year. figure 9arepresents the mechanism on the 29th day. The feeler 52 of the rocker 50 is at this moment positioned against a sector 34b of the profile of the year cam. During the night of the 29th to March 1st, the 24H finger 82 exerts a push on the first jaw 54 of the rocker 50, driving the latter until the second jaw 56 in turn exerts a push on the compensation finger 72 of the star 70 ( figure 9b ) so that it makes two successive jumps. Then finger 66 activates star 70 according to the description above, which makes an additional jump in order to make the transition from the indication of the 29th to the indication of the 1st of March.

[0051] THE figures 10a to 10d represent an operational sequence at the end of April. The figure 10arepresents the mechanism on the 30th day of April. The feeler 52 of the rocker 50 is positioned at this moment against a sector 25a of the profile of the month cam. The finger of 24H 82 exerts a push on the first beak 54 of the rocker 50 according to the figure 10b then the second beak 56 of this one drives the star 70 via the catching finger 72 according to the figure 10c so that the star makes a jump followed by an additional jump under the action of finger 66 which is pivoted thanks to the action of the rocker rake on wheel 62.

[0052] We will note according to the figure 10bThe actuation of the star wheel 70 at the end of the month drives the first wheel 37 via the drive finger 76. The gear train 37, 38 connecting the star wheel 70 to the large wheel 36, as well as the gear train 44, 46 connecting the large wheel 36 to the first wheel 42, as described previously, drive the month cam by one-twelfth of a turn. A sector 25b of the month cam corresponding to a 31-day month, in this case May, is thus located on the path of the feeler 52 of the rocker.

[0053] According to the figure 10d , once the 24H 82 finger is released from the first beak 54 of the rocker, the feeler 52 is brought against the sector 25b under the action of the spiral spring 60.

[0054] The functioning of the sequence described above with reference to the month of April remains identical for the other months of the year which, like the month of April, also have 30 days.

[0055] Various modifications can be made to the date mechanism just described without departing from the invention as defined by the claims. For example, the rocker arm 50 could be configured to directly actuate the star wheel 31 each day so that the latter can, in particular, perform a single jump independently of the rocker arm's amplitude of movement, thus eliminating the need for the finger 66. According to another embodiment, the rocker arm could be replaced by a large conventional rocker arm comprising a large pawl cooperating with a cam 31 fixed to the star wheel 31 in place of the catching finger. Reference list

[0056] Perpetual calendar mechanism 10 Concentric cam assembly 20 Month cam 22 Upper face 23a Lower face 23b 30-day month sectors 25a 31-day month sectors 25b Radial opening 27 Central housing 28 Cylindrical wall 28a Year cam 30 Upper face 32a Lower face 32b Radial notches 34a Sector 34b Large wheel 36 Gear train First and second wheels 42, 44 Drive 46 Jumper 47 Gear train First and second wheels 37, 38 Rocker 50 Feeler 52 First beak 54 Second beak 56 Rake 58 Rocker spring 60 (e.g., spiral) Wheel 62 Finger 66 Star 31-70 Compensating finger 72 Spring blade 73 Jumper 74 Drive finger 76 24-hour wheel 80 24-hour finger 82

Claims

1. Perpetual calendar mechanism (10) for a watch movement, comprising: a set of concentric cams (20) comprising a month cam (22), which comprises a central recess (28) and is arranged to be driven at the rate of one revolution per year, and a year cam (30), which is positioned in the central recess (28) of the month cam (22) and is arranged to be driven at the rate of one revolution every four years, a lever (50) comprising a feeler (52) arranged to cooperate with the set of concentric cams (20), and a star (70) arranged to be actuated daily directly or indirectly by the lever (50) and to be further actuated on the last day of months of less than 31 days, according to the angular position of the month cam (22) and of the year cam (30) in order to effect a catch-up, wherein the month cam (22) comprises a radial opening (27) so that the feeler (52) of the lever (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. Mechanism (10) of claim 1, wherein the thickness of one of the month cam (22) and of the year cam (30) is at least half the thickness of the other of the month cam (22) and of the year cam (30).

3. Mechanism (10) of any preceding claim, wherein at least 3 / 5, preferably at least 4 / 5 of the thickness of one of the month cam (22) and of the year cam (30) is at the level of the thickness of the other of the month cam (22) and of the year cam (30).

4. Mechanism (10) of any preceding claim, wherein the top side (23a) of the month cam (22) is substantially coplanar with the top side (32a) of the year cam (30).

5. Mechanism (10) of any preceding claim, wherein the bottom side (23b) of the month cam (22) is substantially coplanar with the bottom side (32b) of the year cam (30).

6. Mechanism (10) of any preceding claim, wherein the central recess (28) of the month cam (22) comprises a cylindrical wall (28a) arranged against at least a part of the profile of the year cam (30) so that said year cam can guide the month cam in rotation.

7. Mechanism (10) of any preceding claim, wherein the year cam (30) is fixed to a large wheel (36) meshing with at least one wheel (37, 38) arranged to be driven once a month by the star (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. Mechanism (10) of the preceding claim, wherein the feeler (52) of the lever (50) is arranged between the first wheel (42) and the large wheel (36).

9. Mechanism of claim 7 or 8, wherein the first wheel (42) and the month cam (22) form together a single piece.

10. Mechanism of any of claims 7 to 9, wherein the large wheel (36) and the year cam (30) form together a single piece.

11. Mechanism (10) of any preceding claim, wherein the profile of the year cam (30) comprises three radial notches (34a) corresponding to the sectors of the non-leap years of the cam.

12. Mechanism (10) of any preceding claim, further comprising a 24H wheel (80) arranged to be driven at the rate of one revolution in 24H and a 24H finger (82) fixed to the 24H wheel (80), the lever (50) comprising a first beak (54) arranged to cooperate with the 24H finger (82) and a second beak (56) arranged to actuate the star (70) in rotation via a catch finger (72) fixed to the said star.

13. Mechanism (10) of the preceding claim, further comprising a subsequent wheel (62) and a finger (66) fixed to the subsequent wheel (62), the lever (50) comprising a rake (58) in mesh with said subsequent wheel (62) in order to engage the finger (66) with said star (70) each time the lever is actuated by the 24H finger (80).

14. Watch movement comprising the mechanism of any preceding claim.

15. Timepiece, in particular a wristwatch, comprising the watch movement of the preceding claim.