Perpetual calendar mechanism for a clock movement

Abstract

The present invention relates to a perpetual calendar mechanism for a timepiece comprising in the leap year wheel set (11) a toothed member rotatable on the month cam (10), engaged with a fixed toothed member (12) and comprising n series of teeth each formed by a tooth of a first height (112) followed by three teeth of a second height (111) distinct from the first height for n greater than or equal to 1 for a total of 4n teeth, the month feeler (9) being arranged to bear on a tooth of second height (111) of the leap year wheel set (11) during the months of February of a standard year and either on a tooth of first height (112) or on the second portion (102) of the month cam (10) during the month of February of a leap year;and by the fact that the leap year wheel (11), the month cam (10) and the fixed toothed member (12) are arranged so that when the month cam (10) makes one turn the leap year wheel (11) makes x turns plus or minus one tooth for x greater than or equal to 1.;

Description

[0001] The present invention relates to a perpetual calendar mechanism for a clock movement.

[0002] A calendar mechanism can display at least the date, but often also the month, the day of the week, or even the year or the phases of the moon. A perpetual calendar mechanism is particularly designed to change the date at the end of each month of less than 31 days, including February for leap years. To do this, such a mechanism is designed to provide information on the leap year at the level of the month cam.

[0003] Several solutions are described in the book "Les Montres compliqués" by François Lecoultre on pages 216 to 236. In a first alternative, the perpetual calendar mechanism can be arranged with a month star that makes one revolution in 4 years. The month cam then includes forty-eight steps whose depth varies according to the length of the month they determine: 28 high steps for months with 31 days, 16 medium steps for months with 30 days, a special step for the month of February in a leap year and 3 deep steps for the months of February with 28 days. This solution has the disadvantage of being very bulky with wide mobiles.

[0004] In another solution, the size of the month star is reduced: it has twelve teeth and makes one turn per year. It is attached to a month cam comprising eleven steps whose depth determines the months of 30 or 31 days. Between the steps of the months of January and March, the month cam has an opening in which turns a leap year cam: this is a rectangle pivoted on the month star so that three sides are equidistant from the center of rotation of the star and one side is further away. When this last side faces the outside of the opening of the month cam, it indicates a month of February with 29 days and a leap year. The leap year cam must therefore make a quarter turn per year: to do this, a Maltese cross is adjusted square on the axis of the leap year cam and cooperates with a fixed finger attached to the plate.Thus, for each turn of the month star, the leap year cam makes a quarter turn. With this arrangement, an additional level is required for the finger and the Maltese cross.

[0005] In yet another alternative, the leap year cam pivoted on the month cam is secured to a satellite driven by fixed teeth. Replacing the Maltese cross with a satellite and the finger on the month star with fixed teeth does not reduce the thickness of the mechanism. Furthermore, in both cases, it is necessary to index the various components (Maltese cross and leap year cam, finger and month star) during assembly.

[0006] The aim of the present invention is to provide a perpetual calendar mechanism arranged to manage leap years in a very simple manner, without increasing the size of the device or the indexing steps required during assembly and pre-assembly.

[0007] The present invention relates to a perpetual calendar mechanism for a clockwork movement according to claim 1.

[0008] The attached figures illustrate schematically and by way of example an embodiment of the perpetual calendar mechanism according to the invention. In this embodiment, the perpetual calendar mechanism makes it possible in particular to display the date in a retrograde manner. There figure 1 is a top view of a portion of a calendar mechanism according to one embodiment of the invention as of January 31. The figure 2 is a top view of the mechanism of the figure 1 illustrating the transition from January 31 to February 1 (before the leap). The figures 3 And 4 are views from above and below of the mechanism on February 1 (after the jump). figure 5 is a top view of the mechanism illustrating the transition from February 1 to February 2 (before the jump). The figure 6 is a top view of the mechanism as of February 2 (after the jump). The figure 7 is a top view of the mechanism on February 28. The figure 8 is a top view of the mechanism illustrating the transition from February 28 to March 1 (before the jump). The figure 9 is a top view of the mechanism as of February 29. The figure 10 is a top view of the mechanism illustrating the transition from February 29 to March 1 (before the jump). The figure 11 is a top view of the mechanism on March 1 (after the jump). The figure 12 is a top view of the mechanism as of April 30. The figure 13 is a top view of the mechanism illustrating the transition from April 30 to May 1 (before the jump). The figure 14 is a view of the mechanism on May 1st.

[0009] The perpetual calendar mechanism according to the invention is intended to equip a clockwork movement to enable the display of at least the date of the month by automatically changing the date at the end of months of less than 31 days, including February.

[0010] In the embodiment illustrated, the perpetual calendar mechanism allows the date to be displayed retrogradely, that is to say, the date indicator moves along a path on the dial so that when it reaches the end of the month on the 28th, 29th, 30th or 31st, it instantly returns to its starting point on the number 1.

[0011] A 24-hour wheel (not shown) is pivoted at A and is arranged to be driven one revolution per day by the clockwork movement comprising the calendar mechanism. This 24-hour wheel carries a 24-hour finger 1 arranged to drive once a day a large lever 2 pivoted at B on the clockwork movement. Preferably and as shown in the figures, the 24-hour finger 1 cooperates with a correction pawl 21 of the large lever to allow the time display of the clockwork movement to be set counterclockwise without correcting the date and without breaking the mechanism.

[0012] The large lever 2 is subjected to the action of a return spring 22 which tends to keep it in a first rest position resting against a stop not shown. When the 24-hour finger 1 drives the large lever 2, it pivots it at B against the action of its return spring 22.

[0013] A drive pawl 23 is pivoted on the large lever 2 and is subjected to the action of a return spring 230. The drive pawl 23 is intended to cooperate with a date wheel 3 with triangular teeth to advance the latter by one step in a first direction when the large lever 2 pivots driven by the 24-hour finger 1. The date wheel 3 carries a date indicator (not illustrated) which can take any suitable form.

[0014] A jumper 4 positions the date wheel 3 and prevents it from pivoting in a second direction opposite to the first. To do this, the jumper 4 comprises a first positioning arm 41 arranged to cooperate with the teeth 31 of the date wheel 3 for positioning and locking the latter. A return spring 40 is arranged to force the jumper 4 against the teeth 31 of the date wheel 3.

[0015] A blocker 5 is pivoted at C and comprises a first arm 51 arranged to cooperate with a second blocking arm 42 of the jumper 4. The blocker 5 is subjected to the action of its return spring 53 which tends to push said blocker 5 into a position in which the first arm 51 is in abutment against a stud 54 driven into the clockwork movement. The blocker 5 further comprises a second arm 52 arranged to cooperate with an arm 24 of the large lever 2. As will be seen later, the blocker 5 makes it possible to retain the jumper 4 outside the toothing 31 of the date wheel 3 when passing the end of a month to allow the retrograde return of the date wheel 3.

[0016] A date pinion 6 is integral with the date wheel 3 and is engaged with a date rack 7 pivoted at D. The date rack 7 is subjected to the action of its return spring 74 which tends to pivot it towards a stop 75 fixed on the watch movement. In particular, the date rack 7 tends to pivot the pinion 6 and the date wheel 3 in a second direction opposite to the first direction (direction of actuation of the large lever 2 on the date wheel 3). The date rack 7 carries a month pin 71 arranged to cooperate with an intermediate lever 8 pivoted at E on a month lever 9 itself pivoted at F on the watch movement.

[0017] The intermediate lever 8 has a slot 81 crossed by a pin 43 fixed on the jumper 4 of the date wheel 3. When the date rack 7 reaches its high position at the passage from the last day of the month to the first day of the following month, the month pin 71 pushes the intermediate lever 8 which pivots at E and acts on the second pin 43 to pivot the jumper 4 which then releases the date wheel 3 and the blocker 5. The latter then falls to block the jumper 4 outside the teeth 31 of the date wheel 3.

[0018] The month rocker 9 comprises a feeler 91 which is arranged to bear against a month cam 10. The month cam 10 comprises a first portion 101 whose profile is calculated to determine the months with 30 or 31 days between March and January and a second portion 102 for the month of February. This second portion 102 has in its center a notch 1022 to allow a tooth of a leap year cam 11 pivotally mounted on the month cam 10 to pass.

[0019] The role of the leap year cam 11 is to determine whether the current year is a leap year or not, i.e. whether the month of February has 28 or 29 days. According to the invention, the leap year cam 11 is a satellite pivoted on the month cam 10. In the illustrated embodiment, the satellite 11 is formed of 8 teeth, of which six teeth 111 are whole for non-leap years and the months of February with 28 days and 2 teeth 112 are truncated for leap years and the months of February with 29 days (the reverse is of course possible, i.e. six truncated teeth and two whole teeth). The leap year cam 11 is driven by a fixed wheel 12 which is coaxial with the month cam 10 and has 9 teeth in the illustrated embodiment. Therefore, according to the invention, satellite 11 acts directly as a leap year cam.

[0020] The leap year cam 11 and the month cam 10 are arranged so that when a whole tooth 11 is visible in the notch 1022, the latter is filled and the second portion 102 then has the same height or depth over its entire length, while when a truncated tooth 112 is opposite the notch 1022, the feeler 91 of the month lever 9 then falls into said notch 1022 and comes to bear on the truncated tooth 112.

[0021] Alternatively, the second portion 102 of the month cam 10 could not include a notch 1022: in this case, each truncated tooth 112 is arranged so as not to exceed this second portion 102 when they are opposite the latter and facing the outside of the month cam 10. Thus, in February of a leap year, the feeler 91 of the month lever 9 comes to bear on said second portion 102. The whole teeth 111 are arranged to exceed this second portion 102 when they are opposite the latter and facing the outside of the month cam 10. Thus, in February of a non-leap year, the feeler 91 of the month lever 9 comes to bear on one of said whole teeth 111 projecting from the second portion 102 of the month cam 10.

[0022] With this arrangement, the thickness of the calendar mechanism is limited since the fixed wheel 12 and the leap year cam 11 are at the same level and there is no need to provide another wheel.

[0023] In addition, the assembly or pre-assembly of the calendar mechanism is made easier since there is no particular indexing to be done between the satellite and the leap year cam since it is a single mobile, the satellite acting as a cam.

[0024] To return to the calendar mechanism illustrated, thanks to the month cam 10 and the leap year cam 11, the month lever 9 and by extension the intermediate lever 8 can take four different positions depending on the current month.

[0025] To complete the description of the illustrated embodiment, the date rack 7 also carries a month finger 72 pivotally mounted on said rack 7 and subjected to the action of a return spring 73. The month finger 72 is arranged to drive a month star 13 secured to the month cam 10 when the date rack 7 falls. The month star 13 is subjected to the action of its positioning jumper 14 and for its part drives the display of the months.

[0026] This display of months can take any suitable form and will not be described in further detail here.

[0027] The operation of the calendar mechanism according to the embodiment of the invention illustrated in the figures will now be described.

[0028] THE figures 1 , 7 , 9 , 12illustrate the calendar mechanism as described above at the end of the month, respectively January 31, February 28 (non-leap year), February 29 (leap year) and April 30. The large lever 2 is held in its rest position resting on its stop by its return spring 22. The feeler 91 of the month lever 9 rests on the area of ​​the profile of the month cam 10 corresponding to the current month.

[0029] In this end-of-month position, jumper 4 is pushed by its return spring into a position in which its first arm 41 is held in the teeth 31 of date wheel 3. Date wheel 3, date pinion 6 and consequently date rack 7 are thus blocked by jumper 4. Arm 51 of blocker 5 bears against second arm 42 of jumper 4 pushed by its return spring 53. Date rack 7 is engaged with date pinion 6 blocked by jumper 4 but does not cooperate with intermediate lever 8 or month star 13.

[0030] In the figure 1 , the feeler 91 is supported on an area of ​​the first portion 101 of the month cam 10 corresponding to the month of January with 31 days.

[0031] In the figure 12 , the feeler 91 rests on a portion of a step 101 of the month cam 10 whose depth corresponds to a month of 30 days (April).

[0032] There figure 7 illustrates the case of a non-leap year, the month of February ending on the 28th. In this case, the feeler 91 is supported against an entire tooth 111 of the leap year cam 11 which is located in the notch 1022 of the second portion 102 of the month cam 10.

[0033] There figure 9 illustrates the case of a leap year, the month of February ending on the 29th. In this case, the feeler 91 rests against a truncated tooth 112 of the leap year cam 11 which is located in the notch 1022 of the second portion 102 of the month cam 10.

[0034] THE figures 2 , 8 , 10 And 13 illustrate the passage from the last day of the month to the 1st day of the following month just before the retrograde jump, i.e. respectively the passage from January 31 to February 1, from February 28 to March 1, from February 29 to March 1 and from April 30 to May 1.

[0035] At the end of a month, the 24-hour finger 1 driven by the 24-hour wheel comes into contact with the correction pawl 21 and pivots the large lever 2. The drive pawl 23 comes into contact with the toothing 31 of the date wheel 3 to advance the latter by one step in a first direction. Simultaneously, the arm 24 of the large lever 2 comes into contact with the second arm 52 of the blocker 5 and pivots it against the action of its return spring 53.

[0036] By pivoting, the date wheel 3 drives the date pinion 6 which in turn drives the date rack 7 which pivots against the action of its return spring 74 to reach its high position. The month pin 71 then comes into contact with the intermediate lever 8, the position of which is determined by the month lever 9 resting on the month cam 10, and pivots it. The intermediate lever 8 acts on the pin 43 of the jumper 4 and then lifts said jumper 4 into a raised position in which the first arm 41 of said jumper 4 is no longer in the teeth 31 of the date wheel 3 ( figures 2 , 8 , 10 And 13 ).

[0037] The date wheel 3 is released and can then pivot in the second direction under the action of the date rack 7 to bring the date indicator back to the 1st of the month. This retrograde return is detailed below.

[0038] The 24-hour finger 1 continues its rotation until it releases the correction pawl 21. The large lever 2 then returns to its rest position pushed by its return spring 22: the drive pawl 23 comes out of the teeth 31 of the date wheel 3 and the arm 24 of the large lever releases the blocker 5 ( figures 3 And 4 , 11 And 14). In doing so, the blocker 5 pivots until it comes to rest on its stud 54 pushed by its return spring 53. In this position, it prevents the jumper 4 from falling back into the teeth 31 of the date wheel 3 and keeps said jumper 4 in its raised position. Thus, since nothing holds the date wheel 3, the date rack 7 pivots under the action of its return spring 74 and falls until it comes to rest against the stop 75. In doing so, the date rack 7 drives the date pinion 6 which pivots so that the date indicator it carries returns back to indicate the number 1 again.

[0039] According to the illustrated embodiment, when falling, the date rack 7 drives the month star 13 by one step thanks to the month finger 72 which in the high position of the rack, when passing the end of a month, comes into the teeth of the month star 13. The month star 13 drives the month cam 10 which is integral with it and the feeler 91 of the month lever 9 is now opposite the area of ​​the month cam 10 indicating the following month. It is noted that in the illustrated embodiment, the month lever is not subject to the action of a spring. Thus, this month rocker is not always constrained against the month cam 10. At the end of the month, the month pin 71 comes into contact and pushes the intermediate rocker 8 and the month rocker 9 until the feeler 91 of the latter comes to bear against the month cam 10.

[0040] With the rotation of the month cam 10, the leap year cam 11 is driven around the fixed wheel 12. With the ratio of the teeth of the fixed wheel 12 and the leap year cam 11, the latter makes one revolution and one step when the month cam 10 makes one revolution, that is to say one revolution and one step per year. Thus, every February, the leap year cam 11 has a new tooth in the notch 1022 of the month cam 10 (which is the tooth that follows the one that was in the notch 1022 the previous year).

[0041] THE figures 3 And 4 illustrate the case of the transition to February 1 of a non-leap year, the feeler 91 therefore coming to bear on an entire tooth 111 of the leap year cam 11 which is located in the notch 1022 of the second portion 102 of the month cam 10 intended for the month of February.

[0042] THE figures 11 And 14illustrate the case of the transition to March 1, respectively to May 1, the feeler 91 therefore coming opposite a zone of the first portion 101 of the month cam 10 corresponding to the month of March, respectively May.

[0043] Just after the jump, on the 1st of a month, the blocker 5 is still resting on its stud 54 in a position in which it prevents the jumper 4 from falling back into the teeth 31 of the date wheel 3. Said date wheel 3 is positioned by the rack 7 resting on its stop 75. This is preferably adjustable to avoid any display shift between the 1st and the other days of the month.

[0044] THE figures 5 And 6 illustrate the passage from the 1st to the 2nd day of the month, more precisely, the passage from February 1st to February 2nd.

[0045] Starting from the situation of the figure 3 illustrating the 1st of February of a non-leap year, at the end of a day, the 24-hour finger 1 driven by the 24-hour wheel comes into contact with the correction pawl 21 and pivots the large lever 2. The drive pawl 23 comes into contact with the teeth 31 of the date wheel 3 to advance it by one step in a first direction. Simultaneously, the arm 24 of the large lever 2 comes into contact with the second arm 52 of the blocker 5 and pivots it away from the stud 54 against the action of its return spring 53. In doing so, the blocker 5 releases the jumper 4 which falls back into the teeth 31 of the date wheel 3 and resumes its role for positioning and blocking this wheel.

[0046] The date pinion 6 secured to the date wheel 3 in turn drives the date rack 7 which pivots against the action of its return spring 74 and moves away from the stop 75. The indicator carried by the date pinion 6 displays the 2. The date wheel 3 pivots until the arm 41 of the jumper 4 falls back into the teeth 31 ( figure 5 ).

[0047] The 24-hour finger 1 continues its rotation until it releases the correction pawl 21. The large lever 2 returns to its rest position pushed by its return spring 22: the drive pawl 23 comes out of the teeth 31 of the date wheel 3 and the arm 24 of the large lever 2 releases the blocker 5. In doing so, the blocker 5 falls back to rest on the second arm 42 of the jumper 4 ( figure 6 ) which has returned to its position in toothing 31 of date wheel 3. The date indicator now displays 2.

[0048] When the normal date changes during the month, the sequence is substantially the same: The 24-hour finger 1 driven by the 24-hour wheel comes into contact with the correction pawl 21 and pivots the large lever 2. The drive pawl 23 comes into contact with the toothing 31 of the date wheel 3 to advance it by one step in the first direction. Simultaneously, the arm 24 of the large lever 2 comes into contact with the second arm 52 of the blocker 5 and pivots it. The jumper 4 lifts when the date wheel 3 rotates, actuated by the drive pawl 23. As it lifts, the pin 43 of the jumper 4 slides in the slot 81 of the intermediate lever 8 without affecting the position of the latter or of the month lever 9.

[0049] The date pinion 6, secured to the date wheel 3, in turn drives the date rack 7, which pivots a little more against the action of its return spring 74. The date indicator takes one step.

[0050] The 24-hour finger 1 continues its rotation until it releases the correction pawl 21. The large lever 2 returns to its rest position pushed by its return spring 22: the drive pawl 23 comes out of the teeth 31 of the date wheel 3 and the arm 24 of the large lever 2 releases the blocker 5. In doing so, the blocker 5 falls back to rest on the second arm 42 of the jumper 4.

[0051] As stated, the embodiment illustrates a retrograde date display. Alternatively, the arrangement of the leap year cam, fixed wheel, and month cam could work for a standard display.

[0052] Generally speaking, the perpetual calendar mechanism according to the invention comprises: a date wheel arranged to be driven one step per day at the end of the day; a month cam comprising a first portion whose profile determines the 30-day or 31-day months from March to January and a second portion intended for the month of February, the month cam being arranged to advance one step at the end of each month; a leap year wheel pivoted on the month cam in the second portion; a month feeler arranged to bear on the month cam or on the leap year wheel depending on the month and the year and arranged to cooperate with the date wheel when passing from the last day of the month to the first day of the following month depending on the length of the month; a fixed toothed member arranged to cooperate with the leap year wheel.

[0053] According to the invention, the leap year wheel set is a rotating toothed member, engaged with the fixed toothed member and comprising n series of teeth each formed by a tooth of a first height followed by three teeth of a second height distinct from the first for n greater than or equal to 1 for a total of 4n teeth. The month feeler rests on a second height tooth of the cam of the leap year wheel set during the months of February of a standard year and either on a first height tooth or on the second portion of the month cam during the month of February of a leap year. The leap year wheel set, the month cam and the fixed toothed member are arranged so that when the month cam makes one revolution the leap year wheel set makes x revolutions plus or minus one tooth, for x greater than or equal to 1.According to the illustrated embodiment, there are two sets of three whole teeth 111 (second height) followed by a truncated tooth 112 (first height) for a total of 8 teeth, and n is therefore 2. The fixed wheel has 9 teeth so that when the month cam 10 makes one turn, the leap year cam 11 makes 2 turns + 1 tooth.

[0054] This creates a perpetual calendar mechanism in which the leap year information is provided reliably but without encumbering the mechanism, particularly in terms of thickness. Furthermore, special and restrictive indexing is avoided during assembly or pre-assembly of the mechanism.

Claims

1. Perpetual calendar mechanism for a timepiece comprising: • a date wheel set (3, 6) arranged to be driven one step per day at the end of the day; • a month cam (10) comprising a first portion (101) whose profile determines the months of 30 or 31 days from March to January and a second portion (102) intended for the month of February, the month cam (10) being arranged to advance one step at the end of each month; • a leap year wheel set (11) pivoted on the month cam (10) in the second portion (1021); • a month feeler (9) arranged to bear on the month cam (10) or on the leap year wheel set (11) depending on the month and the year and arranged to cooperate with the date wheel set (3, 6) when passing from the last day of the month to the first day of the following month depending on the length of the month; • a fixed toothed member (12) arranged to cooperate with the leap year wheel (11); the mechanism being characterized by the fact thatthe leap year wheel (11) is a toothed member movable in rotation, engaged with the fixed toothed member (12) and comprising n series of teeth each formed by a tooth of a first height (112) followed by three teeth of a second height (111) distinct from the first height for n greater than or equal to 1 for a total of 4n teeth, the month feeler (9) being arranged to come to bear on a tooth of second height (111) of the leap year wheel (11) during the months of February of a standard year and either on a tooth of first height (112) or on the second portion (102) of the month cam (10) during the month of February of a leap year; and by the fact that the leap year wheel (11), the month cam (10) and the fixed toothed member (12) are arranged so that when the month cam (10) makes one revolution the leap year wheel (11) makes x revolutions plus or minus one tooth for x greater than or equal to 1.

2. Perpetual calendar mechanism according to the preceding claim, characterized by the fact that the second portion (102) of the month cam (10) has the shape of a step higher than the first portion (101); and by the fact that the leap year wheel (11) is arranged so that the first height tooth(s) do not protrude from this second portion regardless of their position, while the second height teeth protrude from said portion when they extend radially relative to the month cam (10) and outwards from the latter so that, during a month of February, the month feeler (9) bears either on the second portion of the month cam (10) or on a second height tooth (111) of the leap year wheel (11).

3. Perpetual calendar mechanism according to claim 1, characterized by the fact thatthe second portion (102) of the month cam (10) has an opening (1022) through which the teeth of the leap year mobile (11) pass so that, during a month of February, the month feeler (9) rests either on a first height tooth (112) or on a second height tooth (111) of the leap year mobile (11).

4. Movement comprising a perpetual calendar mechanism according to one of the preceding claims.

5. Timepiece comprising a movement according to the preceding claim.

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