Clock differential comprising a device for taking up play

Abstract

The invention relates to a watch differential (1) comprising at least: - a planet gear (10), - a reference toothed part (20), - a first part (30), as a first satellite, meshed with the reference toothed part (20) and with the planet gear (10), - a second part (40), as a second satellite, meshed with the reference toothed part (20) and with the planet gear (10), characterized in that the watch differential (1) includes a backlash compensation device provided to compensate for: - backlash between the reference toothed part (20) and at least one of the first part (30) and the second part (40) and / or - backlash between the planet gear (10) and at least one of the first part (30) and the second part (40).

Description

Technical field of the invention

[0001] The present invention relates generally to watch gears comprising a play-compensating device, and the invention relates in particular to a watch differential comprising a play-compensating device. State of the art

[0002] In the prior art of watch gears, for example, document EP1704448 B1 is known, which discloses toothed mobiles comprising play-compensating teeth comprising a flexible portion.

[0003] On the other hand, backlash-compensating teeth require a dedicated space greater than that of a conventional "rigid" tooth due to the flexible portion which is generally provided by a material recess. This document does not propose a solution to limit the overall size of a toothed wheel equipped with backlash-compensating teeth and forming part of a gear or a gear train. This space problem is exacerbated in the case where one wants to build a clockwork differential, that is to say an epicyclic train with typically a central sun gear, an outer ring gear and at least two satellites mounted on a planet carrier and meshing with the sun gear and the ring gear. The outside diameter of the differential is directly impacted by the size of the teeth of the different toothed wheels and flexible teeth lead to an increase in the external dimensions of the differential.

[0004] Furthermore, to avoid problems of hyperstaticity, unnecessary friction and / or untimely forces, a backlash (i.e. a tooth of a toothed wheel having a first face in contact with a tooth of another toothed wheel has a clearance between its second face and the next tooth of the other toothed wheel) is still desirable, even if backlash-compensating teeth are provided. Such a backlash must be taken up when reversing the direction of rotation, which implies a lost stroke at the very beginning of the reversal of the direction of rotation. Statement of the invention

[0005] An aim of the present invention is to address the drawbacks of the prior art mentioned above and in particular, first of all, to propose a clockwork gear and in particular a clockwork differential comprising a play-compensating device and which has reduced dimensions and / or minimal or reduced lost travel during a change of direction of rotation.

[0006] For this, a first aspect of the invention concerns a clock differential comprising at least: a planetary gear, a reference toothed part, a first part, such as a first satellite, meshed with the reference toothed part and with the planetary gear, a second part, such as a second satellite, meshed with the reference toothed part and with the planetary gear, characterized in that the clock differential comprises a play compensation device designed to compensate for: a clearance between the reference toothed part and at least one of the first part and the second part and / or a clearance between the sun gear and at least one of the first part and the second part.

[0007] The clockwork differential according to the above implementation makes it possible to take up a clearance between the reference toothed part and at least one of the first part and the second part and / or a clearance between the sun gear and at least one of the first part and the second part, so that when reversing the direction of rotation, the lost travel will be reduced. In addition, it is sufficient to take up a clearance between the reference toothed part and at least one of the first part and the second part or a clearance between the sun gear and at least one of the first part and the second part to guarantee a reduced overall clearance, which avoids the need to provide, for example, clearance-compensating teeth (flexible teeth) on the sun gear and on the reference toothed part, so that the overall size is reduced.

[0008] The clock differential may further have one or more of the following characteristics, taken alone or in combination.

[0009] According to one embodiment, the play compensation device comprises flexible teeth and rigid teeth, arranged so that: when one of the first part and the second part meshes with one of the sun gear and the reference gear via flexible teeth, then the other of the first part and the second part meshes with said one of the sun gear and the reference gear via rigid teeth. In other words, there is always one of the first part and the second part that meshes with one of the sun gear and the reference gear via flexible teeth while the other of the first part and the second part meshes with said one of the sun gear and the reference gear via rigid teeth. As a result, at the rigid teeth, the overall size is reduced, which offers more varied design possibilities.

[0010] In other words, the invention may relate to a gear train for a timepiece, comprising at least: a reference toothed part, a first part, meshed with the reference toothed part, a second part, meshed with the reference toothed part, wherein at least one of the reference toothed part, the first part and the second part comprises flexible teeth, and wherein at least one of the reference toothed part, the first part and the second part comprises rigid teeth, characterized in that the flexible teeth and the rigid teeth are arranged so that: when one of the first part and the second part meshes with the reference toothed part via flexible teeth, then the other of the first part and the second part meshes with the reference toothed part via rigid teeth.

[0011] According to one embodiment, the reference toothed part forms a crown of the clockwork differential and comprises: at least one first toothed portion with flexible teeth, at least one second toothed portion with rigid teeth, a first outer diameter opposite said at least one first toothed portion, a second outer diameter opposite said at least one second toothed portion, and the first outer diameter is greater than the second outer diameter. According to this implementation, the reference toothed part (forming a crown) comprises an alternation of first toothed sectors (first toothed portions) comprising only flexible teeth and second toothed sectors (second toothed portions) comprising only rigid teeth. The second toothed portions have a smaller outer diameter, because the root of the rigid teeth does not require a recess or recessed parts to form flexible portions necessary for the flexible teeth.

[0012] According to one embodiment: said at least one first toothed portion with flexible teeth comprises between 1 and 7 flexible teeth, preferably between 2 and 6 flexible teeth and very preferably between 3 and 5 flexible teeth and for example 3 flexible teeth, said at least one second toothed portion with rigid teeth comprises between 1 and 7 rigid teeth, preferably between 2 and 6 rigid teeth and very preferably between 3 and 5 rigid teeth and for example 3 rigid teeth.

[0013] According to one embodiment, said at least one first toothed portion comprises as many flexible teeth as said at least one second toothed portion comprises rigid teeth.

[0014] According to one embodiment, the clock differential comprises a crown carrier, and: the reference toothed part contacts the crown carrier at the second diameter, and / or the reference toothed part has a clearance with the crown carrier at the first diameter. The assembly or adjustment between the reference toothed part and the crown carrier is carried out on the lateral part of the reference toothed part, which has the smallest diameter, which makes it possible to provide adequate and nevertheless reduced thicknesses and dimensions at the crown carrier.

[0015] According to one embodiment, the reference toothed part is driven into the crown holder.

[0016] According to one embodiment, the reference toothed part is crimped or riveted or welded or glued or screwed into the crown holder.

[0017] According to one embodiment, the crown comprises an odd number of first toothed portions and an odd number of second toothed portions.

[0018] According to one embodiment, with for example the play-compensating device formed by an alternation of rigid teeth and flexible teeth, the first part and the second part are diametrically opposed with respect to a center or with respect to an axis of symmetry of the reference toothed part. In other words, the reference toothed part has at least one shape of revolution (for example a primitive diameter or a primitive circle can be defined by the teeth of the reference toothed part) and the first part and the second part are carried by the same diameter of the reference toothed part. In other words, in this embodiment, the first part and the second part are mounted symmetrically with respect to a plane which contains a central axis of the clockwork differential.

[0019] According to another embodiment, with for example the play-compensating device which is not formed by an alternation of rigid teeth and flexible teeth, each tooth of the reference toothed part has a first face (or a first flank) arranged in a clockwise direction and a second face (or a second flank) arranged in an anti-clockwise direction, and the play-compensating device is arranged to simultaneously impose: a contact of the first part on the first face of a first tooth of the reference toothed part, a contact of the second part on the second face of a second tooth of the reference toothed part. In other words, the play compensation device is arranged to simultaneously impose: a contact between the first part, the sun gear and the reference toothed part in a first direction of rotation, and a contact between the second part, the sun gear and the reference toothed part in a second direction of rotation. According to this implementation, the clockwork differential can guarantee a reversal of the direction of rotation without lost travel, because whatever the direction of rotation, one of the satellites is in contact with the sun gear and the crown. In other words, the first part and the second part are mounted asymmetrically with respect to a plane which contains a central axis of the clockwork differential.For example, the clearance adjustment device may consist of an angular offset of one of the first part and the second part.

[0020] According to one embodiment, each tooth of the planetary gear has a first face (or a first flank) arranged in a clockwise direction and a second face (or a second flank) arranged in a counterclockwise direction, and the play-compensating device is arranged to simultaneously impose: a contact of the first part on the first face of a first tooth of the sun gear, a contact of the second part on the second face of a second tooth of the sun gear. In other words, the play compensation device is arranged to simultaneously impose: a contact between the first part, the sun gear and the reference toothed part in a first direction of rotation, and a contact between the second part, the sun gear and the reference toothed part in a second direction of rotation. According to this implementation, the clockwork differential can guarantee a reversal of the direction of rotation without lost travel, because whatever the direction of rotation, one of the satellites is in contact with the sun gear and the crown. In other words, the first part and the second part are mounted asymmetrically with respect to a plane which contains a central axis of the clockwork differential.For example, the clearance adjustment device may consist of an angular offset of one of the first part and the second part.

[0021] According to one embodiment, the clock differential comprises an elastic catch-up portion, arranged: between the reference part and one of the first part and the second part, and / or between the first part and the second part, and / or between the sun gear and one of the first part and the second part.

[0022] According to one embodiment, the play-compensating device comprises a common support, on which the first part and the second part are mounted in a pivot connection, and the common support defines a mounting position of one of the first part and the second part with an angular offset from a nominal position between the reference toothed part and said one of the first part and the second part, in which the nominal position is a position in which the first part and the second part have a tooth clearance with the reference toothed part distributed on either side of each meshed tooth, and in which the angular offset is less than an angular sector value defined by the tooth clearance.In the present application, the angular sector defined by the backlash covers the possible positions of the first part or the second part (i.e. of a satellite) included in an angular sector going from a first position of the satellite in which the teeth of the satellite are in abutment with the sun gear or the crown in a first direction of rotation, to a second position in which the teeth are in abutment with the sun gear or the crown in a second direction of rotation, the remainder of the differential being fixed. The angular sector defined by the backlash is therefore an angular sector encompassing the theoretical positions permitted by the clearance (the play, without interference) of the satellite relative to the sun gear and the crown, which are fixed and engaged with each other by another satellite (in contact with the sun gear and the crown in a direction of rotation), to determine this angular sector.

[0023] According to one embodiment, the play compensation device comprises a common support comprising: at least one first bearing on or in which the first part is mounted in a pivot connection, a second bearing on or in which the second part is mounted in a pivot connection, at least one flexible structure provided to impose on one of the first bearing and the second bearing an angular offset from a nominal position between the reference toothed part and said one of the first part and the second part, and the nominal position is a position in which the first part and the second part have a tooth clearance with the reference toothed part distributed on either side of each meshed tooth, and the angular offset is less than an angular sector value defined by a tooth clearance.

[0024] According to one embodiment, the angular sector defined by the tooth clearance is preferably less than 3°, preferably less than 2°, and very preferably less than or equal to 1°.

[0025] A second aspect of the invention relates to a timepiece comprising a clockwork differential according to the first aspect. Description of figures

[0026] Other characteristics and advantages of the present invention will appear more clearly on reading the following detailed description of an embodiment of the invention given by way of non-limiting example and illustrated by the appended drawings, in which: [ fig. 1 ] represents a top view of a clock differential according to a first implementation of the invention; [ fig. 2 ] represents a sectional view of the clock differential of the figure 1 along the AA axis of the figure 1 ; [ fig. 3 ] represents a top view of a clock differential according to a second implementation of the invention; [ fig. 4 ] represents a top view of a clock differential according to a third implementation of the invention. Detailed description of embodiment(s)

[0027] There figure 1 represents a top view of a clock differential 1 according to a first implementation of the invention and comprising: a sun gear 10, a reference toothed part 20 forming a crown, a first part 30, forming a first satellite, meshed with the reference toothed part 20 and with the sun gear 10, a second part 40, forming a second satellite, meshed with the reference toothed part 20 and with the sun gear 10, a planet carrier 60, supporting the first part 30 and the second part 40, here mounted in pivot connection on the planet carrier 60 and diametrically opposite each other, a crown carrier 50, itself comprising external teeth and supporting the reference toothed part 20, here mounted in recessed connection in the crown carrier 50.

[0028] It can be noted that the clock differential 1 of the figure 1 comprises a backlash compensation device, here in the form of an alternation of backlash compensation teeth, or flexible teeth 21, and conventional teeth, rigid teeth 22. In this exemplary embodiment, the backlash compensation device aims to reduce a tooth backlash normally present between the satellites and the internal teeth. There may remain a certain backlash (a reduced backlash compared to a known assembly of the prior art) with the reference toothed part 20, in particular between one of the first part 30 and the second part 40, and the reference toothed part 20 (the one which is engaged with the rigid teeth 22).

[0029] In detail, and in the implementation of the figure 1 , the reference toothed part includes a succession or an alternation: first toothed portions P1 comprising flexible teeth 21 and second toothed portions P2 comprising rigid teeth 22.

[0030] In the example of the figure 1 , each first toothed portion P1 comprises three flexible teeth 21 and each second toothed portion P2 comprises three rigid teeth 22. Other numbers of flexible or rigid teeth can be provided. It can be noted that each first toothed portion P1 only comprises flexible teeth 21 and that each second toothed portion P2 only comprises rigid teeth 22.

[0031] As regards the toothed part of reference 20, that is to say the crown of the clockwork differential 1, the figure 1 shows that each first toothed portion P1 has a first outer diameter D1 and each second toothed portion P2 has a second outer diameter D2, smaller than the first outer diameter D1. Indeed, the flexible teeth 21 have a flexible portion and a recess is provided (a slot) over the entire height of each flexible tooth 21, to allow clearance of the flexible portion. Consequently, each flexible tooth 21 requires a space at the root of the tooth greater than that required for a rigid tooth 22, which leads to having a second outer diameter D2 smaller than the first outer diameter D1.

[0032] It may also be noted that the reference toothed part 20 comprises seven first toothed portions P1 and seven second toothed portions P2. Other numbers of first toothed portions P1 and second toothed portions P2 may be provided, but it may be noted that according to the figure 1 , we have an odd number of first toothed portions P1 and an odd number of second toothed portions P2, so that: when one of the first part 30 and the second part 40 meshes with one of the sun gear 10 and the reference toothed part 20 via flexible teeth 21, then the other of the first part 30 and the second part 40 meshes with said one of the sun gear 10 and the reference toothed part 20 via rigid teeth.

[0033] In the example of the figure 1 , the first part 30 meshes with the reference toothed part 20 via rigid teeth 22, and the second part 40 meshes with the reference toothed part 20 via flexible teeth 21, so that the tooth play which normally exists within a clockwork differential comprising only conventional teeth, i.e. rigid teeth without play compensation, can be greatly reduced.

[0034] In particular, it can be noted that each tooth of the second part 40 engaged with the reference toothed part 20 simultaneously presents: a face oriented in the clockwise direction in contact with the thick part of a flexible tooth 21, a face oriented in the counterclockwise direction in contact with the flexible part of another flexible tooth 21. There is no tooth play between the second part 40 and the reference toothed part 20.

[0035] As shown in the section of the figure 2 : the sun gear 10 here forms a central shaft with two cylindrical ends intended to be driven into a frame of a timepiece, the sun gear 10 supports the crown carrier 50 in pivot connection via bearings 80, the crown carrier 50 supports on the one hand the reference toothed part 20 which is driven into the crown carrier 50, and on the other hand supports a pinion 70 intended to engage with another part of a mechanism of the timepiece, the sun gear 10 supports the planet carrier 60 in pivot connection via a bearing 80, the planet carrier 60 comprises two pins 61 to allow coupling with another part of a mechanism of the timepiece.

[0036] In detail, it can be noted that the reference toothed part 20 is driven into the crown carrier 50 at the level of the second external diameter D2, and a clearance is provided between the reference toothed part 20 and the crown carrier 50 at the level of the first external diameter D1. Indeed, as discussed above, the first external diameter D1 is greater than the second external diameter D2.

[0037] Consequently, a first zone 51 of the crown holder 50 has a much lower material thickness than a second zone 52 of the crown holder 50, as clearly shown in figure 2 . Providing radial contact and clamping at the second outer diameter D2 and therefore at the second zone 52 of the crown holder 50 ensures good mechanical strength and a reliable and robust assembly. It could even be provided to completely pass through the material at the first zone 51 of the crown holder 50.

[0038] As a result, the clock differential 1 of the figures 1 et 2 has reduced tooth clearance, reduced dimensions and a robust assembly, particularly between the reference toothed part 20 and the crown carrier 50.

[0039] It may be noted that the alternation of rigid teeth 22 and flexible teeth 21 may be provided on other parts.

[0040] There figure 3 represents a top view of a clock differential 1A according to a second implementation of the invention. In this implementation, only a few parts are specific compared to the clock differential 1 of the figures 1 et 2 , and are as follows: the reference toothed part 20A only comprises rigid teeth, the planet carrier 60A is designed to impose an angular offset DA on the second part 40 relative to a nominal position in which the first part 30 and the second part 40 have a tooth clearance with the reference toothed part 20A distributed on either side of each meshed tooth.

[0041] However, and as the figure 3 , we can note the following points: at least one tooth of the first part 30 engaged with the reference toothed part 20A has a face oriented in the counterclockwise direction in contact with a tooth of the reference toothed part 20A, at least one tooth of the first part 30 engaged with the sun gear 10 has a face oriented in the counterclockwise direction in contact with a tooth of the sun gear 10, at least one tooth of the second part 40 engaged with the reference toothed part 20A has a face oriented in the clockwise direction in contact with a tooth of the reference toothed part 20A, at least one tooth of the second part 40 engaged with the sun gear 10 has a face oriented in the clockwise direction in contact with a tooth of the sun gear 10.

[0042] Accordingly, if an input torque is applied to the reference gear 20A to obtain an output torque to the sun gear 10 with the planet carrier 60A locked, there is "no backlash" or at least extremely low backlash (typically at least to avoid buckling) if the reference gear 20A is rotated clockwise because the torque passes from the reference gear 20A to the sun gear 10 directly through the first part 30 in contact with these two parts. There is also "no backlash" or at least extremely low backlash if the reference gear 20A is rotated counterclockwise because the torque passes from the reference gear 20A to the sun gear 10 directly through the second part 40 also in contact with these two parts.Consequently, in one direction of rotation, the torque is transmitted directly by the first part 30, and in the opposite direction of rotation, the torque is transmitted directly by the second part 40. When reversing the direction of rotation, "no play" or at least extremely low tooth play has to be made up, there is no or almost no lost travel.

[0043] This implementation is made possible by the angular offset DA imposed by the planet carrier 60A on the second part 40. The representation of the angular offset DA is exaggerated in the figure 3 , because if we consider a tooth clearance of approximately 0.02 mm, for a primitive diameter of the second part of 2 millimeters mounted at 3 millimeters from the center of rotation of the planet carrier, then the angular offset can be approximately 1°. It can be noted that the second part 40 can have a plurality of nominal positions (with the tooth clearance distributed on either side of each engaged tooth), all spaced by an angle separating two teeth of the planetary 10. In any case, the offset DA is chosen to have at best: at least one tooth of the first part 30 engaged with the reference toothed part 20A which has a face oriented in the counterclockwise direction in contact with a tooth of the reference toothed part 20A, at least one tooth of the first part 30 engaged with the sun gear 10 which has a face oriented in the counterclockwise direction in contact with a tooth of the sun gear 10, at least one tooth of the second part 40 engaged with the reference toothed part 20A which has a face oriented in the clockwise direction in contact with a tooth of the reference toothed part 20A, at least one tooth of the second part 40 engaged with the sun gear 10 which has a face oriented in the clockwise direction in contact with a tooth of the sun gear 10. The angular offset DA therefore acts as a play-compensating device to reduce a total tooth play of the clockwork differential 1A.

[0044] There figure 4 represents a top view of a clock differential 1B according to a third implementation of the invention. In this implementation, only a few parts are specific compared to the clock differential 1 of the figures 1 et 2 , and are as follows: the reference toothed part 20B comprises only rigid teeth, the planet carrier 60B is provided to impose an angular offset DA on the second part 40 relative to a nominal position in which the first part 30 and the second part 40 have a tooth clearance with the reference toothed part 20B distributed on either side of each meshed tooth. Furthermore, it can be noted that the planet carrier 60B comprises an elastic portion 61B (a curved and elongated arm) which carries the fixing bearing of the second part 40, so that the position of the latter can automatically adapt to the position of the other parts, to avoid any interference and / or any untimely force / friction.

[0045] However, and as the figure 4 , we can note the points below (as for the figure 3 ) : at least one tooth of the first part 30 engaged with the reference toothed part 20B has a face oriented in the counterclockwise direction in contact with a tooth of the reference toothed part 20B, at least one tooth of the first part 30 engaged with the sun gear 10 has a face oriented in the counterclockwise direction in contact with a tooth of the sun gear 10, at least one tooth of the second part 40 engaged with the reference toothed part 20B has a face oriented in the clockwise direction in contact with a tooth of the reference toothed part 20B, at least one tooth of the second part 40 engaged with the sun gear 10 has a face oriented in the clockwise direction in contact with a tooth of the sun gear 10.

[0046] Accordingly, if an input torque is applied to the reference gear 20B to obtain an output torque to the sun gear 10 with the planet carrier 60B locked, there is no backlash if the reference gear 20B is rotated clockwise because the torque passes from the reference gear 20B to the sun gear 10 directly through the first part 30 in contact with these two parts. There is also no backlash if the reference gear 20B is rotated counterclockwise because the torque passes from the reference gear 20B to the sun gear 10 directly through the second part 40 also in contact with these two parts. Consequently, in one direction of rotation, the torque is transmitted directly by the first part 30, and in the opposite direction of rotation, the torque is transmitted directly by the second part 40. When reversing the direction of rotation, no tooth play needs to be made up, there is no lost travel.

[0047] This implementation is made possible by the angular offset DA imposed by the planet carrier 60B on the second part 40. The representation of the angular offset DA is exaggerated in the figure 3 , because if we consider a tooth clearance of approximately 0.02 mm, for a primitive diameter of the second part of 2 millimeters mounted at 3 millimeters from the center of rotation of the planet carrier, then the angular offset can be approximately 1°. It can be noted that the second part 40 can have a plurality of nominal positions (with the tooth clearance distributed on either side of each engaged tooth), all spaced by an angle separating two teeth of the planetary 10. In any case, the offset DA is chosen to have at best: at least one tooth of the first part 30 engaged with the reference toothed part 20B which has a face oriented in the counterclockwise direction in contact with a tooth of the reference toothed part 20B, at least one tooth of the first part 30 engaged with the sun gear 10 which has a face oriented in the counterclockwise direction in contact with a tooth of the sun gear 10, at least one tooth of the second part 40 engaged with the reference toothed part 20B which has a face oriented in the clockwise direction in contact with a tooth of the reference toothed part 20B, at least one tooth of the second part 40 engaged with the sun gear 10 which has a face oriented in the clockwise direction in contact with a tooth of the sun gear 10. The angular offset DA and / or the elastic portion 61B therefore act as a play-compensating device to reduce a total tooth play of the clockwork differential 1B. Industrial application

[0048] A clock differential according to the present invention, and its manufacture, are capable of industrial application.

[0049] It will be understood that various modifications and / or improvements obvious to those skilled in the art may be made to the various embodiments of the invention described in the present description without departing from the scope of the invention. In particular, it may be noted that the rigid teeth and the flexible teeth of the first embodiment may be implanted on other parts of the clockwork differential. Their number and the number of portions with flexible / rigid teeth may also be modified. Flexible teeth may also be provided in the second and third embodiments. Provision may be made to implant the planet carrier of the second or third embodiment in the first embodiment.

Claims

1. Clock differential (1; 1A; 1B) comprising at least: - a sun gear (10), - a reference toothed part (20; 20A; 20B), - a first part (30), such as a first satellite, meshed with the reference toothed part (20; 20A; 20B) and with the sun gear (10), - a second part (40), such as a second satellite, meshed with the reference toothed part (20; 20A; 20B) and with the sun gear (10), characterized in that the clock differential (1; 1A; 1B) comprises a play-compensating device designed to compensate for: - play between the reference toothed part (20; 20A; 20B) and at least one of the first part (30) and the second part (40) and / or - play between the sun gear (10) and at least one of the first part (30) and the second part (40).

2. Clock differential (1) according to claim 1, wherein the play-compensating device comprises flexible teeth (21) and rigid teeth (22), arranged so that: - when one of the first part (30) and the second part (40) meshes with one of the sun gear (10) and the reference toothed part (20) via flexible teeth (21), - then the other of the first part (30) and the second part (40) meshes with said one of the sun gear (10) and the reference toothed part (20) via rigid teeth (22).

3. Clock differential (1) according to claim 2, in which the reference toothed part (20) forms a crown of the clock differential (1) and comprises: - at least a first toothed portion (P1) with flexible teeth (21), - at least a second toothed portion (P2) with rigid teeth (22), - a first outside diameter (D1) opposite said at least one first toothed portion (P1), - a second outside diameter (D2) opposite said at least one second toothed portion (P2), and in which the first outside diameter (D1) is greater than the second outside diameter (D2).

4. Clock differential (1) according to claim 3, comprising a crown carrier, in which: - the reference toothed part (20) contacts the crown carrier at the level of the second diameter, and / or - the reference toothed part (20) has play with the crown carrier at the level of the first diameter.

5. Clock differential (1) according to claim 4, in which the reference toothed part (20) is driven into the crown holder.

6. Clock differential (1) according to claim 4 or 5, in which the reference toothed part (20) is crimped or riveted or welded or glued or screwed into the crown holder.

7. Clock differential (1) according to one of claims 3 to 6, in which the crown comprises an odd number of first toothed portions (P1) and an odd number of second toothed portions (P2).

8. Clock differential (1) according to one of claims 1 to 7, in which the first part (30) and the second part (40) are diametrically opposed relative to a center or relative to an axis of symmetry of the reference toothed part (20).

9. Clock differential (1; 1A; 1B) according to one of the preceding claims, in which each tooth of the reference toothed part (20; 20A; 20B) has a first face arranged in a clockwise direction and a second face arranged in a counterclockwise direction, and in which the play-compensating device is arranged to simultaneously impose: - contact of the first part (30) on the first face of a first tooth of the reference toothed part (20; 20A; 20B), - contact of the second part (40) on the second face of a second tooth of the reference toothed part (20; 20A; 20B).

10. Clock differential (1; 1A; 1B) according to one of the preceding claims, in which each tooth of the sun gear (10) has a first face arranged in a clockwise direction and a second face arranged in a counterclockwise direction, and in which the play compensation device is arranged to simultaneously impose: - contact of the first part (30) on the first face of a first tooth of the sun gear (10), - contact of the second part (40) on the second face of a second tooth of the sun gear (10).

11. Clock differential (1; 1A; 1B) according to one of the preceding claims, comprising an elastic take-up portion (61B), arranged: - between the reference part and one of the first part (30) and the second part (40), and / or - between the first part (30) and the second part (40), and / or - between the sun gear (10) and one of the first part (30) and the second part (40).

12. Clock differential (1; 1A; 1B) according to one of the preceding claims, wherein the play-compensating device comprises a common support, on which the first part (30) and the second part (40) are mounted in pivot connection, and the common support defines a mounting position of one of the first part (30) and the second part (40) with an angular offset (DA) from a nominal position between the reference toothed part (20; 20A; 20B) and said one of the first part (30) and the second part (40), in which the nominal position is a position in which the first part (30) and the second part (40) have a tooth clearance with the reference toothed part (20; 20A; 20B) distributed on either side of each meshed tooth, and in which the angular offset (DA) is less than an angular sector value defined by the play of teeth.

13. Clock differential (1; 1A; 1B) according to one of claims 1 to 11, wherein the play-compensating device comprises a common support comprising: - at least one first bearing in which the first part (30) is mounted in a pivot connection, - a second bearing in which the second part (40) is mounted in a pivot connection, - at least one flexible structure provided to impose on one of the first bearing and the second bearing an angular offset (DA) from a nominal position between the reference toothed part (20; 20A; 20B) and said one of the first part (30) and the second part (40), in which the nominal position is a position in which the first part (30) and the second part (40) have a tooth clearance with the reference toothed part (20; 20A; 20B) distributed on either side of each meshed tooth, and in which the angular offset (DA) is less than to an angular sector value defined by a tooth clearance.

14. Clock differential (1; 1A; 1B) according to one of claims 12 or 13, in which the angular sector defined by the set of teeth is 1°.

15. Timepiece comprising a clockwork differential (1; 1A; 1B) according to one of the preceding claims.

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