Leap year display mechanism of a perpetual calendar clock

Description

Technical field of the invention

[0001] The invention falls within the field of watchmaking, and in particular watch parts with perpetual calendar display.

[0002] More specifically, the invention relates to a leap year display mechanism for a perpetual calendar display watch movement. Technological background

[0003] Among the horological complications that allow the display of a date, we know of perpetual calendar display mechanisms that allow the date to be indicated by automatically adapting, that is to say without manual intervention, to the length of the month, notably taking into account leap years.

[0004] In some timepieces, the perpetual calendar display mechanism is linked to a display indicating whether the current year is a leap year or a normal year; see, for example, document EP 3 040 787 A1 in the name of Montres Breguet SA

[0005] These mechanisms are complex to manufacture and assemble. Furthermore, they generally consume a lot of energy. Summary of the invention

[0006] The invention solves the aforementioned drawbacks by proposing a solution for displaying leap years with a relatively simple design and minimal energy consumption.

[0007] The mechanism according to the invention is particularly suited to a roller display.

[0008] To this end, the present invention relates to a leap year display mechanism for a perpetual calendar watch movement comprising: A drive element connected to a month wheel rotated one step per month; a transmission star intended to be fixed to a structure of the clock movement, arranged on the travel of the drive element so as to be driven in rotation by the latter when the month wheel completes a full revolution; a leap year display connected to the transmission star by means of a reduction gear so that with each revolution completed by the month wheel, the leap year display is driven in rotation one step; the leap year display having the form of a roller comprising a display face on which are represented indications representative of the type of year in progress, including a leap year and normal years.

[0009] In particular embodiments, the invention may further comprise one or more of the following features, taken individually or in all technically possible combinations.

[0010] In particular embodiments, the drive element has the form of a finger fixed eccentrically on the mobile of the months by means of a mechanical connection of the fixed type.

[0011] In particular embodiments, the transmission star has four teeth.

[0012] In particular embodiments, the leap year display includes an annular bearing by which it is fixed to the reduction gear, said annular bearing being connected to the display wall by means of an end wall.

[0013] In particular embodiments, the leap year display includes a mechanism for adjusting its angular position formed by a radial tab fixed to the annular bearing, by which said annular bearing is connected to the end wall, said radial tab comprising a tapped hole with which cooperates a screw engaged in an oblong hole made in the end wall and extending in a curvilinear direction.

[0014] In particular embodiments, the reduction gear comprises a first wheel fixed coaxially to the transmission star with which it is rotationally fixed and a second wheel fixed coaxially to the leap year display with which it is rotationally fixed.

[0015] In particular embodiments, the reduction gear is configured so that one step of the leap year display corresponds to one eighth of a turn of the latter. Brief description of the figures

[0016] Other features and advantages of the invention will become apparent from the following detailed description, given by way of non-limiting example, with reference to the accompanying drawings in which: there figure 1 represents a partially exploded perspective view of a leap year display mechanism for a perpetual calendar watch movement according to a preferred embodiment of the invention; the figure 2 represents a cross-sectional view of a detail of the display mechanism of the figure 1 ; there figure 3 represents a cross-sectional view along the cutting axis AA of the figure 2 ; there figure 4 represents a cross-sectional view along the cutting axis BB of the figure 2 .

[0017] Note that the figures are not necessarily drawn to scale for reasons of clarity. Detailed description of the invention

[0018] As seen in the exploded view of the figure 1 The invention relates to a leap year display mechanism for a perpetual calendar display watch movement.

[0019] The leap year display mechanism 10 includes a month wheel 20 driven in rotation by one step per month, to which is connected a drive element 21. The drive element 21 advantageously has the shape of a finger in the preferred embodiment of the invention, and is fixed by means of a mechanical connection of the type of fixed joint on the month wheel 20, i.e. without degree of freedom.

[0020] The drive element 21 is advantageously fixed eccentrically with respect to the axis of rotation of the mobile of months 20, as shown in the figure 1, and is designed to drive a transmission star 30 in rotation by one step for each revolution made by the month wheel 20. In particular, the transmission star 30 is intended to be fixed in a movable manner relative to a structure of the watch movement (not shown in the figures), such as a mainplate or a bridge, preferably by means of a support structure 31 shown in the figures 2 And 3 .

[0021] The transmission star 30 is connected to a leap year display 40 via a reduction gear 32 so that with each turn made by the month wheel 20 the leap year display 40 is driven in rotation by one step.

[0022] In the embodiment shown in the figures, the present invention is advantageously applied to a roller date display. Alternatively, it can be adapted to any type of date display without presenting any design difficulties for those skilled in the art. In particular, the present invention can be adapted to a disc date display.

[0023] As seen on the Figures 1 And 2The month display 20 is in the form of a roller comprising a plurality of panels 22 indicating the names of the months. These panels 22 are arranged to be supported by a frame that rotates relative to the support structure 31 and, in the preferred embodiment of the invention, are also rotated relative to said frame. In particular, the month display 20 comprises six panels 22, each indicating two different months, arranged to complete a half-turn for every full rotation of the frame. The frame is driven in rotation by a calendar mechanism known per se to those skilled in the art, so as to complete one full rotation in six months. Such a month display 20 is described in more detail in patent EP3267266.

[0024] The chassis is, for example, formed by a shaft 23, each end of which is rotationally fixed to a flange 24, as seen in the exploded view of the figure 1or on the cross-sectional view of the figure 2 In particular, each end of the shaft 23 is arranged to pivot within a support structure 31 intended to be fixed to the structure of the watch movement. The drive element 21 is preferably fixed to one of these flanges 24 so as to pivot around the longitudinal axis of the shaft 23 when the month wheel 20 is driven in rotation.

[0025] The support structure 31 may include a groove 310 extending in a circle whose center is aligned with the axis of rotation of the shaft 23, such that the drive element 21 can be housed in said groove 310 throughout its stroke. This feature makes it possible to reduce the dimensions of the display mechanism according to the invention.

[0026] Advantageously, as the figure 1The reduction gear 32 comprises a first wheel 320 fixed coaxially to the transmission star 30, with which it is rotationally fixed, and a second wheel 321 fixed coaxially to the leap year display 40, with which it is rotationally fixed. As can be seen in the cross-sectional view of the figure 2 The second wheel 321 comprises a tubular portion 323 with which it is arranged on the support structure 31 in a rotationally movable manner. In the preferred embodiment of the invention, the leap year display 40 cooperates with the tubular portion 323 of the second wheel 321 in order to exhibit a degree of rotational mobility relative to the support structure 31, as described in more detail below.

[0027] As shown by Figures 1 , 2 And 4 , the reduction gear 32 therefore preferentially comprises only two wheels.

[0028] Furthermore, the axes of rotation of the drive element 21, the transmission star 30, the first and second wheels 320 and 321 of the reduction gear 32 and the leap year display 40 are parallel to each other.

[0029] Advantageously, the reduction gear 32 can include a retaining star 322 fixed in rotation with the second wheel 321 and configured to cooperate with a jumper 33 so as to hold the second wheel 321, and consequently the leap year display 40, in a predefined discrete angular position.

[0030] Preferably, as shown in the exploded view of the figure 1 and the cross-sectional view of the figure 4 , the jumper 33 is configured to be held in contact against the retaining star 322 by a jumper spring 34.

[0031] Alternatively, the jumper 33 can itself be formed by an elastic blade and can be positioned to support the retaining star 322 by deforming said elastic blade. In this case, the leap year display mechanism 10 does not then have a separate jumper spring.

[0032] In the preferred embodiment of the invention, the reduction gear 32 is configured so that one step of the leap year display 40 corresponds to one-eighth of a turn. In particular, the drive element 21 drives the transmission star 30 through a quarter turn, and the reduction gear 32 is dimensioned to generate a reduction ratio of one-half, the retaining star 322 having eight teeth. Since the month wheel 20 completes two full rotations in one year, the leap year display 40 is driven to rotate at a rate of one full rotation every four years.

[0033] The leap year display 40 carries indications 41 representative of the type of year in question, including a leap year and normal years. In particular, the indications 41 of the leap year display 40 present a sequence of eight characters intended to be visible one after the other, with two successive characters displayed per year. In the preferred embodiment, these characters are formed by the following sequence: 1, 1, 2, 2, 3, 3, B, B.

[0034] The indications 41 can be seen through a window in a dressing piece covering the leap year display 40 (not shown in the figures).

[0035] The leap year display 40 has the form of a roller comprising a cylindrical display wall 42 on which are displayed the indications 41 representing the type of year in question. Furthermore, the leap year display 40 has an annular bearing 43 by means of which it is fixed without degrees of freedom to the second wheel 321 of the reduction gear 32, and in particular to the tubular portion 323, as shown in the figure 2 More specifically, the annular bearing surface 43 can be pressed or bonded to the tubular portion 323. The latter may advantageously include splines or any other rotational locking element, such as a key, etc. The annular bearing surface 43 is connected to the display wall 42 via an end wall 44, as shown in the embodiment example visible on the figure 2 .

[0036] Advantageously, the leap year display 40 can include a mechanism for adjusting its angular position. More precisely, as schematically shown in the figure 2 The adjustment mechanism can be formed by a radial tab 45 fixed to the annular bearing 43, by which said annular bearing 43 is connected to the end wall 44 and thus to the display wall 42. In particular, the radial tab 45 includes a tapped hole with which a screw 46 is intended to cooperate, engaged in an oblong hole 47 extending in a curvilinear direction made in the end wall 44. The curvilinear direction is defined by an arc of a circle whose center is aligned with the axis of rotation of the leap year display 40.

[0037] Thus, when the screw 46 is loosened, the display wall 42 has a mobility relative to the annular bearing 43 corresponding to an angular displacement defined by the stroke of the screw 46 between the two ends of the oblong hole 47. When the screw 46 is tightened, the leap year display 40 is held in position.

[0038] Several adjustment mechanisms corresponding to the one described above can be considered, i.e. several radial tabs 45, screws 46 and oblong holes 47, as visible on the figure 1 .

[0039] Advantageously, the annular bearing 43, and consequently the second wheel 321 and the leap year display 40, is fixed in translation relative to the support structure 31 by means of a central screw 48 provided to cooperate with a threaded hole made in said support structure 31. In particular, as can be seen in the cross-sectional view of the figure 2, the tubular portion 323 is interposed between two axial stops materialized by a screw head of the central screw 48 and by the support structure 31, thus eliminating any translational mobility of the second wheel 321 and the leap year display 40.

[0040] More generally, it should be noted that the implementation and realization methods considered above have been described as non-limiting examples, and that other variants are therefore conceivable without departing from the scope of the invention as defined by the attached claims.

Claims

1. Leap-year display mechanism (10) for a horological movement with a perpetual calendar display comprising: - a drive element (21) connected to a month wheel set (20) rotated by one step per month, - a transmission star (30) intended to be attached to a structure of the horological movement, arranged along the stroke of the drive element (21) so as to be rotated thereby when the month wheel set (20) completes one full revolution, - a leap-year display (40) connected to the transmission star (30) via a reduction gear train (32) so that with each revolution of the month wheel set (20), the leap-year display (40) is rotated by one step the leap-year display (40) taking the form of a roller comprising a display wall (42) on which indications (41) representative of the current type of year are shown, including a leap year and normal years.

2. Display mechanism according to claim 1, wherein the drive element (21) takes the form of a finger attached eccentrically to the month wheel set (20) by a mechanical connection of the embedded type.

3. Display mechanism according to claim 1 or 2, wherein the transmission star (30) has four teeth.

4. Display mechanism according to claim 1, wherein the leap-year display (40) includes an annular bearing surface (43) by which it is attached to the reduction gear train (32), said annular bearing surface (43) being connected to the display wall (42) by means of an end wall (44).

5. Display mechanism according to claim 4, wherein the leap-year display (40) includes a mechanism for adjusting the angular position thereof, formed by a radial lug (45) attached to the annular bearing surface (43), by means whereof said annular bearing surface (43) is connected to the end wall (44), said radial lug (45) comprising a threaded hole cooperating with a screw (46) engaged in an oblong hole (47) made in the end wall (44) and extending in a curvilinear direction.

6. Display mechanism according to one of claims 1 to 5, wherein the reduction gear train (32) includes a first wheel (320) rigidly attached coaxially to the transmission star (30) for rotation therewith, and a second wheel (321) rigidly attached coaxially to the leap-year display (40) for rotation therewith.

7. Display mechanism according to one of claims 1 to 6, wherein the reduction gear train (32) is configured such that one step of the leap-year display (40) corresponds to one eighth of a revolution.