CH714617B1 - Movement and timepiece. - Google Patents

Abstract

The object of the present invention is to propose a movement and a timepiece of reduced thickness while ensuring the level of power reserve of the main barrel spring. Such a movement comprises: a first mobile (42) which is rotatably mounted at the front of a plate (21) and to which a rotational force from a movement barrel (41) is transmitted; a third mobile which is rotatably mounted at the front of the plate (21) and to which a rotational force of the first mobile (42) is transmitted; a rear cog (33) rotatably mounted at the rear of the plate (21); and a central transmission wheel (45) which forms a connection between the rear wheel train (33) and the first wheel set (42), and which transmits the rotational force of the first wheel set (42) to the rear wheel train (33).

Description

BACKGROUND OF THE INVENTION

1. Field of the invention

The present invention relates to a movement and a timepiece.

2. Description of prior art

[0002] In the movement of a timepiece, a movement barrel is driven in rotation by the return force of a mainspring housed in the movement barrel, whereby a rotational force is transmitted to the various gear trains. For example, patent document 1 (JP-A-2004-170271) discloses a structure in which a large mobile and a third mobile are successively connected to the barrel of the movement.

In patent document 1, a third pinion of the third mobile meshes with a large wheel of the large mobile and a drive wheel. On the other hand, a third wheel of the third mobile meshes with a seconds pinion of a seconds mobile.

[0004] In this structure, the third wheel set is driven in rotation by the rotational force of the large wheel set, the second wheel set rotating every 60 seconds, and the drive wheel set rotating every 60 minutes.

SUMMARY OF THE INVENTION

[0005] An object of the present application is to achieve an improvement in a movement comprising a large mobile which is rotatably mounted at the front of a plate and to which a rotational force of a movement barrel is transmitted, a third mobile which is rotatably mounted at the front of the plate and to which a rotational force of the large mobile is transmitted, as well as a rear cog rotatably mounted at the rear of the plate. The desired improvement is more precisely an improvement in terms of degree of freedom for the arrangement of the third mobile.

[0006] In order to achieve the above object, it is proposed, according to the present invention, a movement comprising: a first mobile which is rotatably mounted at the front of a plate and to which a rotational force of a movement barrel is transmitted; a third mobile which is rotatably mounted at the front of the plate and to which a rotational force of the first mobile is transmitted; a rear cog rotatably mounted at the rear of the plate; and a central transmission wheel which forms a connection between the rear wheel train and the first wheel set, and which transmits the rotational force of the first wheel set to the rear wheel train.

[0007] According to the invention, the rear wheel train is kinematically connected to the first wheel set via the central transmission wheel, such that, compared to a conventional structure in which the third wheel set is kinematically connected to the first wheel set and to the rear wheel train ( for example, the driving mobile), it is possible to achieve the aforementioned improvement in terms of the degree of freedom for the arrangement of the third mobile. Thus it is possible to move the third wheel set far from the movement barrel, and it is possible, for example, to make an arrangement according to which the third wheel set and the movement barrel are not superimposed on each other according to a plan view. Therefore, it is possible to guarantee the thickness of the movement barrel while achieving a reduction in the thickness of the movement. By guaranteeing the thickness of the movement barrel, it is possible to house a large mainspring in the movement barrel, so that it is possible to ensure the duration of the power reserve of the main barrel spring.

[0008] In the above movement, the central transmission wheel can be arranged at the front of the plate, and the central transmission wheel and the rear cog can be connected to each other via an opening in communication formed in the plate.

In the presently described embodiment, it is possible to mount the central transmission wheel to the plate during the assembly process on the front side of the plate, thus making it possible to easily kinematically connect the first mobile to the wheel. transmission center.

[0010] In the above movement, the central transmission wheel can engage with a drive wheel constituting the rear wheel.

[0011] According to this embodiment, the rotational force of the first mobile is transmitted to the drive mobile via the central transmission wheel, so that, compared for example to the case where the central transmission wheel is kinematically connected to an hour wheel, it is possible to reduce the transmission ratio between the central transmission wheel and the rear wheel. Consequently, the transmission of the rotational force from the first mobile to the rear wheel can be carried out smoothly.

[0012] In the movement of the above mode, the third mobile can be located so as not to overlap the movement barrel according to a plan view taken in the direction of the thickness of the plate.

[0013] In this embodiment, it is possible to guarantee the thickness of the movement barrel while eliminating any interference between the third mobile and the movement barrel. Consequently, it is possible to achieve a reduction in the thickness of the movement while ensuring the duration of the power reserve of the main barrel spring.

[0014] The movement can be according to claim 5.

[0015] According to the present embodiment, the external diameter of the second mobile (seconds wheel) itself can be reduced, so that it is possible to eliminate the overlap or overlap according to a plan view of the second mobile -towards a peripheral element (for example, a ratchet). Therefore, it is possible to achieve an additional reduction in thickness for the movement. Furthermore, it is possible to reduce the external diameter of the second mobile, so that there is no need to excessively reduce the dimensions of the module (diameter of the internal pitch circle / number of teeth) of the second mobile in order to guarantee the acceleration ratio of the second mobile relative to the escape mobile. Consequently, it is possible to effectively transmit the rotational force of the second wheel set to the escape wheel set.

[0016] Furthermore, the outer diameter of the second mobile is reduced, whereby it is also possible to improve the possibilities of arrangement of the third mobile.

[0017] The movement can be according to claim 6.

[0018] According to the present mode, the speed of rotation in revolutions per minute (often indicated via the acronym RPM, for "rounds per minute") of the third mobile and that of the central transmission wheel are increased compared to that of the first mobile, so that the number of teeth of the first mobile can be easily adjusted. Therefore, unlike the conventional case, where the third mobile is used for both accelerating the first mobile and braking the driving mobile, it is possible to realize an improvement in rotational force transmission efficiency.

[0019] A timepiece according to one mode of this patent application can be fitted with a movement of the above mode.

[0020] According to this embodiment, it is possible to provide a fine timepiece, but whose power reserve is high (long life of the barrel spring).

[0021] According to one mode of the present application, it is possible to propose a fine movement and a timepiece ensuring the power reserve of the mainspring.

BRIEF DESCRIPTION OF DRAWINGS

Figure 1 is an external view of a timepiece. Figure 2 is a plan view of a movement seen from the front side. Figure 3 is a plan view of the movement seen from the rear side. Figure 4 is a sectional view along the IV-IV axis of Figure 2. Figure 5 is a sectional view along the V-V axis of Figure 2. Figure 6 is a sectional view along the axis VI-VI of figure 2.

Description of preferred embodiments

In the following, an embodiment of the present invention will be described with reference to the drawings.

timepiece

[0024] Figure 1 is an external view of a timepiece 1. In the following drawings, certain timepiece components are omitted and each timepiece component is represented in a simplified manner so as to to facilitate the understanding of the drawings.

As can be seen in Figure 1, in the timepiece 1 according to the present embodiment, a movement 2, a dial 3, indicator hands 4 to 6, etc. are incorporated in a case 7 of a timepiece.

The case 7 of the timepiece is equipped with a middle case 11, a case back (not shown), and a protective glass 12 (the crystal). A crown 15 is provided at the level of a side surface of the middle 11 of the case corresponding to the position at 3 o'clock (see the right side in FIG. 1). Crown 15 is used to operate movement 2 from outside middle 11 of the case. The crown 15 is fixed to a winding stem 19 inserted in the middle 11 of the case.

Movement

[0027] In movement 2, several wheels etc. are rotatably mounted on a plate 21 constituting the base plate of the movement 2. The aforementioned winding stem 19 is inserted into the plate 21. The winding stem 19 is used when correcting the date and time. The winding stem 19 is rotatable around its axis, and can be moved in the axial direction. In the following description, reference is made to the side of the protective glass or glass 12 (the side of the dial 3) of the case 7 of the timepiece relative to the plate 21 as being the "rear side" of the movement 2 , and to the rear side of the case (the side opposite that of dial 3) as the "front side" of movement 2. Each toothed wheel described below is arranged such that its axial direction is the front-rear direction of movement 2.

Figure 2 is a plan view of the movement 2 seen from the front side. Figure 3 is a bottom view of movement 2 seen from the rear side.

The movement 2 mainly has a front gear train 31 and an escapement-regulator 32 arranged at the front of the plate 21, as illustrated in FIG. 2, and a rear cog 33 arranged at the rear of the plate 21, as can be seen in Figure 3.

Front gear train

[0030] Figure 4 is a sectional view along line IV-IV of Figure 2.

As illustrated in Figure 4, the front gear train 31 is mainly equipped with a movement barrel 41, a large mobile 42 (corresponding to what is called the first mobile in the claims), d a third wheel set 43, a second wheel set 44 constituting the second wheel set, and a central transmission wheel 45 (see FIG. 6). The front gear train 31 constitutes an acceleration cog in which the speed of rotation in revolutions per minute (RPM for "rounds per minute") of a wheel is all the higher as the steps of transmission.

[0032] The movement barrel 41 is rotatably mounted between the plate 21 and a barrel bridge 51. The movement barrel 41 contains a mainspring, also called the main spring (not shown) serving as a source of energy for the part. watchmaking 1. The mainspring is wound via a ratchet 46, for example, by turning the winding stem 19. The movement barrel 41 is driven in rotation by the rotational force (return force of the spring wound on itself ) when the mainspring is in its wound state. In the timepiece 1 of this embodiment, the mainspring can also be wound under the action of the rotation of an oscillating mass 40 following the movements of the user. Movement 2, however, may consist of a structure having no oscillating mass 40.

[0033] The large mobile 42 is rotatably mounted between the plate 21 and the gear bridge 52. The axis of the large mobile 42 is arranged so as not to overlap the movement barrel 41 according to a plan view taken in the direction before behind. A center pinion 42a of the large mobile 42 meshes with a barrel wheel 41a of the movement barrel 41. Therefore, the large mobile 42 is rotated by the rotational force transmitted from the movement barrel 41.

The third mobile 43 is rotatably mounted between the plate 21 and the gear bridge 52. The axis of the third mobile 43 is arranged so as not to overlap the movement barrel 41 and the large mobile 42 according to a view in plan. A third pinion 43a of the third mobile 43 meshes with a large wheel 42b (corresponding to what is called the wheel of the first mobile in the appended claims) of the large mobile 42. According to the present embodiment, the number of teeth of the third pinion 43a is less than the number of teeth of the big wheel 42b.

A third wheel 43b of the third mobile 43 is arranged so as not to overlap the movement barrel 41 in a plan view. More specifically, the third wheel 43b is arranged in height in a space comprising the thickness of the movement barrel 41 (that is to say of the barrel drum 41b) in the front-rear direction. The third wheel 43b, however, can be arranged to be offset relative to the barrel drum 41b in the front-rear direction.

The second mobile 44 is rotatably mounted between the plate 21 and the gear bridge 52. The second mobile 44 is arranged coaxially with respect to the center of the movement 2. A second pinion 44a of the second mobile 44 meshes with the third wheel 43b. A second shaft 44b of the second mobile 44 is rotatably inserted into a central tube 47 fixed to the plate 21. The central tube 47 extends through the plate 21 in the front-rear direction and protrudes from the rear side of the plate 21. In the second mobile 44, the rear end of the second shaft 44b protrudes from the rear side beyond the central tube 47.

Exhaust-regulator

As illustrated in Figure 2, the escapement-regulator 32 is kinematically connected to the output of the front gear train 31 via an intermediate escapement wheel 48. The escapement-regulator 32 controls the rotation of the movement barrel 41. The escapement-regulator 32 has an escapement wheel set 61, an anchor 62 and a spiral balance wheel 63.

[0038] Figure 5 is a sectional view along the line V-V of Figure 2.

As illustrated in Figure 5, the escape wheel set 61 is rotatably mounted between the plate 21 and an escape wheel bridge 54. An escape pinion 61a of the escape wheel set 61 meshes with an intermediate wheel 48a of the intermediate escapement wheel 48. The intermediate escapement wheel 48 is rotatably mounted between the gear train bridge 52 and the escapement wheel bridge 54. An intermediate pinion 48b of the intermediate escapement wheel 48 meshes with a seconds wheel 44c of the second mobile 44. The escape pinion 61a can mesh directly with the seconds wheel 44c.

As illustrated in Figure 2, the anchor 62 is rotatably mounted between the plate 21 and an anchor bridge 55, in a front-rear direction corresponding to the front-rear direction of the movement. The anchor 62 is fitted with a pair of vanes 65a and 65b. When pallet 62 alternately rotates back and forth, pallets 65a and 65b engage alternately with an escape wheel 61b of escape wheel set 61. Rotation of escape wheel set 61 is temporarily stopped when one of the pallets of the pair of pallets 65a and 65b is engaged with the escapement wheel 61b. The escape wheel set 61 rotates when the pair of pallets 65a and 65b are disengaged from the escape wheel 61b. These operations are repeated continuously, and through the latter, the escape wheel set 61 rotates intermittently.

[0041] The spiral balance wheel 63 regulates the escapement wheel set 61 (ie causes the escapement wheel set 61 to rotate at a fixed speed). More specifically, the spiral balance 63 is rotatably mounted between the plate 21 and a balance bridge 56, its axial direction corresponding to the front-rear direction of the movement. More specifically, the spiral balance wheel 63 is rotated reciprocating at a fixed frequency by virtue of the energy transmitted by a spiral spring 67 (see FIG. 5). The spiral balance 63 comes into engagement with a fork 62a of the lever 62, and disengages therefrom repeatedly (see FIG. 5) in synchronization with the alternating rotational movement. Consequently, via the alternating rotation of the anchor 62, the pallets 65a and 65b engage with the escapement wheel set 61 and disengage from it repeatedly.

Rear wheel

[0042] Figure 6 is a sectional view along the VI-VI axis of Figure 2.

As illustrated in Figures 3 and 6, the rear wheel 33 mainly has a drive wheel 71, a minute wheel 72 (see Figure 3), and an hour wheel 73.

As shown in Figure 6, at the rear of the plate 21, the mobile drive 71 is rotatably inserted into the central tube 47 mentioned above. The mobile drive 71 is kinematically connected to the front gear train 31 via the central transmission wheel 45.

As illustrated in Figure 3, the minute wheel set 72 is rotatably mounted on the plate 21. A minute wheel 72a of the minute wheel set 72 meshes with a driving pinion 71a of the drive wheel set 71.

As shown in Figure 5, the hour wheel 73 is inserted into the drive wheel set 71. The hour wheel 73 can rotate between the plate 21 and an hour wheel support 58 relative to the wheel set. drive 71. A minute pinion 72b (see Figure 3) of the minute wheel set 72 meshes with the hour wheel 73.

According to the present embodiment, the number of teeth of the second mobile 44 (the second mobile) mentioned above is set so that it performs one rotation every 60 seconds. In the seconds mobile 44, the seconds hand 6 is mounted on the rear end of the second shaft 44b.

The number of teeth of the mobile drive 71 is adjusted so that it performs one rotation every 60 minutes. The minute hand 5 is mounted on the part of the driving wheel set 71 protruding from the rear of the movement, beyond the hour wheel support 58.

The number of teeth of the hour wheel 73 is adjusted so that it completes one rotation in 12 hours. The hour hand 4 is mounted at the part of the hour wheel 73 protruding from the rear of the movement beyond the hour wheel support 58.

Here, as illustrated in Figure 6, the central transmission wheel 45 mentioned above performs the connection between the large mobile 42 and the mobile drive 71, that is to say ensures the kinematic connection between these two motives. The central transmission wheel 45 is rotatably mounted on the part of the plate 21 located at the rear of the barrel 41 of the movement. According to the plan view of Figure 6, the entire central transmission wheel 45 overlaps the movement barrel 41. The central transmission wheel 45, however, can be arranged so as to only partially overlap the movement barrel 41 according to a plan view, or it can be arranged so as not to overlap the barrel 41 of the movement at all in a plan view.

According to this embodiment, the central transmission wheel 45 is located at the rear of the third wheel 43b. A transmission wheel 45a of the central transmission wheel 45 meshes with the large wheel 42b. In other words, the rotational force of large mobile 42 is transmitted to central transmission wheel 45 and to third mobile 43 via large wheel 42b.

At the part of the plate 21 adjacent to the central transmission wheel 45, a communication opening 21a is formed, establishing communication between the front and the rear of the plate 21. A drive wheel 71b of the mobile drive 71 and a transmission pinion 45b of the central transmission wheel 45 faces the communication opening 21a. The driving wheel 71b and the transmission pinion 45b mesh with each other through the communication opening 21a. While in the embodiment described above the main wheel set 42 and the driving wheel set 71 are connected to each other by a central transmission wheel 45, this should not be interpreted restrictively. For example, the large mobile 42 and the drive mobile 71 could be kinematically linked through a plurality of center transmission wheels.

Operation of the timepiece

In what follows, the operation of the timepiece 1 described above will be described.

In the timepiece 1 of this embodiment, when the movement barrel 41 is driven by the return force of the mainspring, the large mobile 42, the third mobile 43, and the second mobile 44 are driven in rotation while being controlled by the escapement-regulator 32.

The rotational force of the large mobile 42 is transmitted to the central transmission wheel 45 in addition to the third mobile 43. Consequently, the central transmission wheel 45 rotates, and, thanks to the latter, the mobile drive 71 is also spinning. The rotational force of drive wheel 71 is transmitted to hour wheel 73 via minute wheel 72, which in turn rotates hour wheel 73.

[0056] Consequently, the timepiece 1 counts the passing time.

Thus, according to this proposed embodiment, a central transmission wheel 45 is provided kinematically connecting the large mobile 42 to the rear cog 33 (formed by the mobile drive 71).

In such a configuration, the rear cog 33 is kinematically connected to the large mobile 42 via the central transmission wheel 45, so that in comparison with a conventional structure, in which the third mobile is kinematically connected to the large mobile and to the driving mobile, it is possible to achieve an improvement in terms of degree of freedom for the arrangement of the third mobile 43. Consequently, it is possible to move the third mobile 43 away from the movement barrel 41, making it possible, for example, an arrangement of the third mobile 43 and the movement barrel 41 such that they do not overlap each other in a plan view. Therefore, it is possible to guarantee the thickness of the barrel 41 of the movement while achieving a reduction in thickness of the movement 2. By guaranteeing the thickness of the movement barrel 41, it is possible to accommodate a large mainspring in the barrel 41 of the movement, so that it is possible to ensure the power reserve, that is to say the life of the mainspring.

According to this embodiment, the central transmission wheel 45 is arranged at the front of the plate 21, and the central transmission wheel 45 and the mobile drive 71 are connected to each other. via the communication opening 21a of the plate 21.

In such a structure, it is possible to mount the central transmission wheel 45 to the plate 21 during the assembly process of the front of the plate 21, and the kinematic connection of the large mobile 42 to the central wheel transmission 45 is facilitated.

According to the present embodiment, the central transmission wheel 45 is kinematically connected to the mobile drive 71 of the rear cog 33.

In such a structure, the rotational force of the large mobile 42 is transmitted to the mobile drive 71 via the central transmission wheel 45, so that compared, for example, to the case where the central transmission wheel 45 is connected to the hour wheel 73, it is possible to decrease the transmission ratio between the central transmission wheel 45 and the rear cog 33. Consequently, it is possible to transmit the rotational force of the gear train more smoothly. front gear 31 to rear cog 33.

In this embodiment, the third mobile 43 is arranged so as not to overlap the movement barrel 41 in a plan view.

In such a configuration, it is possible to guarantee the thickness of the movement barrel 41 while eliminating the interference between the third mobile 43 (the third wheel 43b) and the movement barrel 41. Consequently, it is possible to achieve a reduction in the thickness of movement 2 while ensuring the power reserve duration of the main spring of the barrel.

According to the present embodiment, the second mobile 44 and the escapement mobile 61 are kinematically connected to each other via the intermediate escapement wheel 48.

[0066] In such a configuration, it is possible to reduce the external diameter of the seconds wheel 44 (the seconds wheel 44c), so that it is possible to eliminate any overlap between the seconds wheel 44c and a peripheral element. (eg ratchet 46) in plan view. This helps to achieve an additional reduction in thickness for movement 2. Furthermore, it is possible to decrease the external diameter of the seconds wheel 44c, so that there is no need to excessively reduce the dimensions of the module (diameter of the pitch circle/number of teeth) of the seconds wheel 44c in order to guarantee the acceleration ratio of the seconds wheel 44c with respect to the escape wheel set 61 (the escape pinion 61a). Consequently, it is possible to effectively transmit the rotational force of the second wheel set 44 to the escape wheel set 61.

[0067] In addition, the external diameter of the seconds wheel 44c is reduced, so that it is possible to achieve an improvement in terms of flexibility for the arrangement of the third mobile 43.

In the present embodiment, the number of teeth of the third mobile 43 (the third wheel 43b) and the number of teeth of the central transmission wheel 45 (the transmission wheel 45a) are lower than the number of teeth of the large mobile 42 (the big wheel 42b).

In such a configuration, the number of revolutions per minute (rpm, acronym for "rounds per minute") of the third mobile 43 and that of the central transmission wheel 45 is increased compared to that of the large mobile 42, such that the number of teeth of the large wheel 42b can be easily set. Therefore, unlike the conventional case where the third mobile (the third pinion) is used both for the acceleration of the large mobile (the large wheel) and the braking of the driving mobile, it is possible to achieve an improvement in terms of transmission efficiency of the rotational drive force.

The timepiece 1 of this embodiment is equipped with the movement 2 described above, so that it is possible to provide a timepiece 1 which is thin, and which moreover has a long-lasting power reserve.

Other possible variants

The preferred embodiment of the present invention described above should not be construed restrictively. It is possible to add, delete, replace, and make other modifications to components without departing from the scope and spirit of the present invention. The present invention is not restricted to the above description but is restricted only to the appended claims.

[0072] For example, whereas according to the embodiment described above the large mobile 42 and the driving mobile 71 are kinematically connected to each other via the central transmission wheel 45, this should not be interpreted restrictively. For example, the central transmission wheel 45 can be connected to any wheel (for example, the hour wheel 73) constituting the rear cog 33.

[0073] While in the embodiment described above the central transmission wheel 45 is arranged at the front of the plate 21, this should not be interpreted restrictively either. The central transmission wheel 45 can be arranged at the rear of the plate 21.

[0074] While in the embodiment described above the central transmission wheel 45 increases the number of revolutions per minute of the large mobile 42 and transmits this speed of rotation to the rear cog 33, this should not be interpreted in such a way restrictive. The central transmission wheel 45 could also reduce the number of revolutions per minute of the large mobile 42.

Apart from these modifications, the components of the embodiment described above can be replaced by known components without departing from the scope of the spirit of the present invention. Further, the modifications and variations described above can be appropriately combined as needed.

Description of reference numbers and signs

[0076] 1 timepiece 2 movement 21 plate 21a communication opening 32 escapement-regulator 33 rear wheel train 41 movement barrel 42 large mobile 43 third mobile 44 seconds mobile 45 central transmission wheel 61 escapement mobile 71 mobile d 'training

Claims (8)

1. Movement (2) comprising: a first mobile (42) which is rotatably mounted at the front of a plate (21), that is to say on the side opposite that of the dial (3), and to which rotational force of a movement barrel (41) is transmitted; a third mobile (43) which is rotatably mounted at the front of the plate (21) and to which a rotational force of the first mobile (42) is transmitted; a rear cog (33) rotatably mounted at the rear of the plate (21); And a central transmission wheel (45) which forms a connection between the rear wheel train (33) and the first wheel set (42), and which transmits the rotational force of the first wheel set (42) to the rear wheel train (33). 2. Movement (2) according to claim 1, in which the central transmission wheel (45) is arranged at the front of the plate (21), and the central transmission wheel (45) and the rear cog (33) are connected to each other via a communication opening (21a) formed in the plate (21). 3. Movement according to one of claims 1 and 2, wherein the central transmission wheel (45) meshes with a mobile drive (71) constituting the rear wheel. 4. Movement according to one of claims 1 to 3, wherein the third mobile (43) is arranged not to overlap the movement barrel (21) according to a plan view taken in the direction of the thickness of the plate . 5. Movement according to one of claims 1 to 4, in which are arranged: a second wheel set which is a seconds wheel set (44), which is rotatably mounted at the front of the plate (21) and to which the rotational force of the third wheel set (43) is transmitted, an escapement-regulator (32) which has an escapement mobile (61) capable of repeatedly coming into engagement with an anchor (62) via a reciprocating rotary movement of this anchor (62), so to rotate intermittently, and which controls the rotation of the movement barrel (41), and an intermediate escape wheel providing the connection between the escape wheel set (61) and the second wheel set (44). 6. Movement according to one of claims 1 to 5, wherein the third mobile (43) comprises a third pinion (43a), and wherein the number of teeth of the third pinion (43a) meshing with a wheel (42b) of the first mobile (42), and the number of teeth of the central transmission wheel (45a) meshing with the wheel (42b) of the first mobile (42) are lower than the number of teeth of the wheel (42b) of the first mobile (42 ). 7. Movement according to one of claims 1 to 6, wherein the first mobile (42) is a large average mobile, the third mobile (43) being an average mobile. 8. Timepiece equipped with a movement according to claim 6 or 7.