CH716783B1 - Timepiece comprising two regulating organs. - Google Patents

Abstract

The present invention relates to a timepiece comprising at least a first movement arranged to produce a first function and regulated by a first regulating organ (13) and a second movement arranged to produce a second function and regulated by a second regulating organ (15 ). At least one of the first and second regulating members (13, 15) is a flexible guide oscillator, the other of the first and second regulating members (13, 15) preferably being a spiral spring balance. The first movement may be a basic movement indicating the current time, the first regulating member (13) being a balance spring-spring, and the second movement may be an auxiliary movement, the second regulating member (15) being a guided oscillator flexible. This auxiliary movement can be a chronograph movement.

Description

The present invention relates to a timepiece comprising at least a first movement arranged to produce a first function and regulated by a first regulating member and a second movement arranged to produce a second function and regulated by a second regulating member.

[0002] When a timepiece comprises a basic movement provided with a main mechanism for indicating the time as well as an auxiliary mechanism, such as a complication such as a chronograph mechanism, a a single source of energy, such as a barrel, to power the main mechanism of the base movement and a single regulating organ to regulate said main mechanism, the auxiliary chronograph mechanism being punctually driven by the base movement by means of a clutch device. This single regulating organ is traditionally a spiral spring balance operating at low frequency, generally less than 5Hz. However, the disadvantage of such a spiral spring balance operating at low frequency is to obtain a precision of the chronograph which may not be sufficient when it is desired to produce a mechanical chronograph displaying the 100th of a second. Furthermore, the use of a single spiral spring balance operating at a higher frequency, for example greater than 10 Hz, may also prove to be unsatisfactory because this would induce, in particular at the level of the pivots of the axis of the spiral spring balance, greater friction which would have a negative influence on the performance of the regulating organ and on the behavior of the parts over time, as well as difficulties in managing lubrication.

[0003] Moreover, since the complication at least temporarily requires a surplus of energy to function, the single energy source will occasionally provide less torque, which will have a chronometric influence on the basic movement.

[0004] To solve these problems, it has for example been proposed in patent EP 1 333 345 a timepiece comprising a base movement, indicating the current time, regulated by a spiral spring balance at 4 Hz and a module autonomous chronograph, mounted superimposed on the basic movement, and regulated by a spiral spring balance wheel at 50 Hz. However, such a high frequency of a spiral spring balance wheel leads to the drawbacks already described above in particular at the level of the pivots of the axis of the spiral spring balance, even if they only have an influence on the autonomous chronograph mechanism. Furthermore, the timepiece comprises two independent motor organs, in the sense that neither of them supplies energy to the other, one dedicated to the base movement and the other dedicated to the module autonomous chronograph. The use of two independent movements makes it possible to avoid any chronometric influence between said movements, the chronograph not disturbing the rate of the base movement when the complication is in operation. Each driving member is in the form of a barrel comprising a drum, a spiral mainspring or "mainspring" housed in the drum, a barrel arbor and a cover. However, these two driving members as well as the other elements of the movements require a large volume since it is necessary to provide in the timepiece the volume necessary for the base movement indicating the current time and for the superimposed autonomous chronograph module.

The present invention aims to remedy these drawbacks by proposing a timepiece comprising two movements, each regulated by a regulating member, making it possible to optimize the overall operation of the timepiece.

The present invention also aims to provide a timepiece comprising two movements to avoid any chronometric influence between said movements, while occupying a limited volume.

To this end, the present invention relates to a timepiece comprising at least a first movement arranged to produce a first function and regulated by a first regulating member and a second movement arranged to produce a second function and regulated by a second regulating organ.

According to the invention, at least one of the first and second regulating members is a flexible guide oscillator.

[0009] Preferably, one of the first and second regulating members can be a flexible-guided oscillator and the other of the first and second regulating members can be a spiral spring balance.

[0010] Advantageously, the first and second regulating members have different frequencies, chosen according to the nature of the regulating member and the function of the movement.

[0011] Thus, the association of two types of regulating members with two specific types of movement allows optimum operation of the overall movement of the timepiece.

Other characteristics and advantages of the present invention will appear on reading the following detailed description of various embodiments of the invention, given by way of non-limiting examples, and made with reference to the accompanying drawings in which : FIG. 1 is a top view of a first embodiment of a timepiece according to the invention; Figure 2 is an axial sectional view of the two barrels and their respective winding devices according to the invention; and Figure 3 is a schematic sectional view of another embodiment of a timepiece according to the invention.

The present invention relates to a timepiece comprising at least a first movement arranged to produce a first function and regulated by a first regulating member and a second movement arranged to produce a second function and regulated by a second regulating member, separate of the first regulating organ,

[0014] A watch movement essentially comprises a source of energy, constituted for example by a barrel, a watch mechanism which comprises a set of organs, and in particular cogs, arranged to produce its function, and supplied with energy by said source of energy, an escapement and a regulating organ.

[0015] In the present description, such a watch mechanism may comprise, for example, a gear train whose function is to transmit the energy from the energy source to the regulating member, equipping the basic movement of a part clock which manages the time to indicate the current time, for example. It can also be a mechanism having another well-defined function, for example a mechanism of a complication formed of a set of organs necessary for the operation of said complication. This mechanism can thus be, for example, a chronograph mechanism, in the broad sense of the term, comprising in particular a chronograph gear train as well as the other necessary elements or components arranged to produce all types of counting/counting down of time and fraction of time, such as as, for example, a standard chrono, a countdown, a regatta chrono, rattrapante, lightning and fraction of a second. Such a mechanism can also be a date mechanism with a date wheel, a moon mechanism with a moon wheel, or an alarm or striking mechanism.

[0016] Thus, the first movement comprises a first barrel, a first mechanism arranged to produce the first function, a first escapement and a first regulating member, constituting a first kinematic chain. The second movement comprises a second barrel, a second mechanism arranged to produce the second function, a second escapement and a second regulating organ distinct from the first regulating organ, constituting a second kinematic chain.

According to the invention, at least one of the first and second regulating members is a flexible guide oscillator. Such an oscillator with flexible guidance is described for example in publication EP 3 502 784 by the applicant.

[0018] Preferably, one of the first and second regulating members may be an oscillator with flexible guidance and the other of the first and second regulating members may be a traditional spiral spring balance.

Advantageously, the first and second regulating members have different frequencies, chosen according to the nature of the regulating member and the function of the movement.

[0020] More particularly, the first movement can be a basic movement which manages the hours to indicate, for example, the current time, the first regulating organ being a spiral spring balance and the second movement can be an auxiliary movement managing a complication, the second regulating member being an oscillator with flexible guidance.

[0021] Preferably, the auxiliary movement is a chronograph movement.

Thus, with reference to Figures 1 and 2 representing a preferred embodiment of the invention, the timepiece comprises a first movement, such as a basic movement to indicate the current time, powered by a first motor member in the form of a first barrel 1, and regulated by a spiral spring balance 13, and a second movement or auxiliary movement managing a complication, such as a chronograph, supplied with energy by a second motor member under the shape of a second barrel 2 and regulated by a flexible guide oscillator 15.

Advantageously, the first and second regulating members 13, 15 have different frequencies, independently of their nature. More particularly for a timepiece combining a basic movement and a chronograph movement, the first regulating organ 13 of the basic movement can have a low frequency, less than 10 Hz, and preferably less than or equal to 5 Hz, and the second regulating member 15 of the chronograph movement may have a high frequency, greater than 10 Hz, preferably greater than or equal to 20 Hz, and more preferably greater than or equal to 50 Hz. More specifically, the first regulating member 13 of the base movement is a spiral spring balance having a low frequency, less than 10 Hz, for example 5 Hz, and the second regulating member 15 of the chronograph movement is a flexible-guided oscillator having a high frequency, for example 50 Hz.

[0024] The hairspring balance, which has the advantage of being robust to external disturbances for low frequencies, is particularly suitable for use in the basic movement managing the current time. The flexible-guided oscillator, which has the advantages of reliability and low energy for high frequencies, and can eliminate dry friction, is particularly suitable for use in the chronograph movement. The association of these two types of regulating members with the two specific types of base and chronograph movements is therefore optimal for the overall movement of the timepiece.

In the example shown, the first and second barrels 1, 2 are separate from each other so that the first kinematic chain constituting the first movement is independent of the second kinematic chain constituting the second movement.

With more specific reference to Figure 2, the first barrel 1 comprises a first drum 3 whose bottom 3a has at its outer periphery a first toothing 4 meshing with a pinion 6a of a wheel 6 of a going train belonging to the first mechanism 7 of the first basic movement, a first spring 8 housed in the first drum 3 and a first barrel shaft 10 around which the first drum 3 is rotatably mounted, as will be described more precisely below. The outer end of the first spring 8 is coupled to the inner surface of the wall of the first drum 3 in a traditional way, for example by means of a flange, which can be slippery to avoid an overtension of the spring in case excessive winding. The inner end of the first spring 8 is coupled to a hook provided on a first bung 10c of the first barrel shaft 10 in a traditional way as well.

The last wheel 9 of the first mechanism 7 meshes with the escapement wheel 11a of the first escapement 11 whose lever 11b cooperates with the first regulating member 13.

Thus, the first barrel 1, the first mechanism 7, the first escapement 11 and the first regulating member 13 form the first timepiece movement, namely the basic movement of the timepiece to indicate the current time, following a first kinematic chain.

The second barrel 2 comprises a second drum 12 whose bottom 12a has at its outer periphery a second toothing 14 meshing with a pinion 16a of a wheel 16 of a chronograph gear train belonging to the second chronograph mechanism 17 of the second chronograph movement, a second spring 18 housed in the second drum 12 and a second barrel shaft 20 around which the second drum 12 is rotatably mounted, as will be described more precisely below. The outer end of the second spring 18 is coupled to the inner surface of the wall of the second drum 12 in a traditional way, for example by means of a flange, which can be slippery to avoid over-tensioning of the spring in the event of excessive winding. The inner end of the second spring 18 is coupled to a hook provided on a second bung 20a of the second barrel shaft 20 in a traditional manner as well.

The last wheel 19 of the second mechanism 17 meshes with the escapement wheel 21a of the second escapement 21 whose anchor 21b cooperates with the second regulating member 15.

Thus, the second barrel 2, the second mechanism 7, the second escapement 21 and the second regulating member 15 form the second watch movement, namely a chronograph movement, following a second kinematic chain, different from the first kinematic chain .

[0032] It is obvious that the combination described here of a first basic movement with a going train to indicate the current time and of a second chronograph movement, powered by their respective energy source, can be replaced by any other possible combination of two movements provided respectively with a regulating organ and with a mechanism arranged to produce an appropriate function and powered by their respective energy source, the type of regulating organ and its frequency being chosen according to the movement. For example, the two movements can be movements to each indicate a different time, or one of the movements can be a basic movement to indicate the current time, the other movement being an alarm or bell movement, such as a minute repeater.

[0033] Preferably, the timepiece comprises a single and unique plate 30 and the first and second barrels 1, 2 are arranged to be mounted superimposed and movable in rotation on said plate 30, between said plate 30 and a bridge of barrel 31 (cf. FIG. 2), the first and second barrel shafts 10, 20 being coaxial along an axis 22 and the interior of the first and second drums 3, 12 facing each other. More particularly, the housings defined by the drums 3 and 12 receiving the first and second springs 8, 18 respectively are arranged facing each other, the bottoms 3a and 12a of the first and second drums 3, 12 respectively being located axially opposite each other, and the first and second barrels 1, 2 having no cover, the first and second springs 8, 18 being separated from each other by a gap.

[0034] In addition, at least the first and second mechanisms 7 and 17 are also mounted on said same plate 30. This means for example that the shafts of the organs of the going train of the first mechanism 7 and of the chronograph train of the second mechanism 17 are pivotally mounted between plate 30 and corresponding bridges fixed to plate 30. Preferably, the shafts of the gear train members of the first mechanism 7 as well as the shafts of the chronograph gear train members of the second mechanism the same side of the plate 30.

Advantageously, the other elements of the first and second kinematic chains of the first and second movements, such as the first and second exhausts 11, 21 as well as the first and second regulating members 13, 15, are also mounted on the same plate 30. This means for example that the shafts of the escapements 11, 21 and of the regulating members 13, 15 are pivotally mounted between the plate 30 and corresponding bridges fixed on the plate 30. Preferably, the shafts of the escapements 11, 21 and regulating organs 13, 15 are mounted on the same side of plate 30.

[0036] Preferably, the first and second barrels 1, 2, the shafts of the gear train members of the first mechanism 7, the shafts of the gear train members of the second mechanism 17, as well as the shafts of the escapements 11, 21 and regulating members 13, 15 are mounted on the same side of the plate, as shown in Figures 1 and 3.

For this purpose, the plate 30 includes different recesses to accommodate the different elements of the first and second movements. Advantageously, recesses are arranged on the same side of the plate 30 so that elements of the first movement are arranged substantially next to elements of the second movement in an optimized manner to occupy approximately half of the surface available on platinum. For example, starting from the first and second superimposed barrels 1 and 2, the going train of the first mechanism 7, the first escapement 11 and the first regulating member 13 are arranged next to the chronograph gear train of the second mechanism 17, of the second escapement 21 and the second regulating member 15 in an optimized manner in order to reduce the size. This arrangement also advantageously makes it possible to be able to mount on plate 30 and disassemble elements of the basic movement indicating the current time and elements of the chronograph movement independently of each other as well as to test each of the corresponding kinematic chains independently of one of the other. It is obvious that any other arrangement, starting from the first and second barrels 1 and 2 superimposed, of the elements of the basic movement indicating the current time and of the elements of the chronograph movement on the plate 30 can be envisaged, all or part of the mobiles can be nested on top of each other.

In a particularly advantageous manner, all the elements constituting the first and second movements are mounted on the same plate 30.

Preferably, as shown in Figure 3, other elements of the first and second mechanisms 7, 17 can be mounted on the side of the plate 30 opposite the side which carries in particular the first and second barrels 1, 2. For example, the other elements of the second mechanism 17 which are different from the chronograph gear train, such as the chronograph control 55, a column wheel, etc., are mounted on the plate 30 and a corresponding bridge 57, on the side opposite to the chronograph gear train. Shaft 51 carrying a chronograph hand 53 is also mounted on plate 30, on the side opposite the chronograph gear train.

According to the particularly advantageous embodiment shown in Figure 3, the plate 30 is arranged between the bottom 64 and the dial 66 of the timepiece so that at least the regulating members 13, 15 are mounted side background. Preferably, the first and second barrels 1, 2, the shafts of the components of the going train of the first mechanism 7, the shafts of the components of the chronograph gear train of the second mechanism 17, as well as the shafts of the escapements 11, 21 and of the components regulators 13, 15 are mounted on plate 30 and corresponding bridges 31, 59, bottom side. The second barrel 2 is here mounted closest to the plate 30, unlike the constructions shown in the other figures. The other elements of the second mechanism 17 are mounted on the dial side. In particular, the shaft 51 carrying the chronograph hand 53, as well as the chronograph control 55 are mounted on the dial side.

This advantageous arrangement allows on the one hand to be able to easily access the regulating members 13, 15 located on the bottom side, in particular after casing, in order to be able to adjust the adjustment of the rate, if necessary. This arrangement also makes it possible to use shafts 51 carrying the chronograph hands 53 of shorter length than when they have to cross the two sides of the plate. These shafts can then be manufactured more simply, which makes it possible to increase their reliability. In addition, the needle display system can easily be replaced by a disc display positioned just under dial 66.

[0042] It is obvious that it is also possible to mount a movement on each side of the plate, by providing the references and passages necessary for the mechanism of the movement which is on the side of the plate opposite to that of the barrels can cooperate with its associated barrel.

In the variant shown in Figures 1 and 2, the timepiece according to the invention comprises two winding devices, that is to say a winding device for each of the barrels 1, 2 of so that the two barrels 1, 2 are independent when winding and unwinding their respective springs 8, 18.

[0044] More specifically, there is provided a first device for winding the first barrel 1 comprising a first winding wheel 52 coaxial along the axis 22 with the first barrel 1, the first barrel arbor 10 and the first winding wheel winding 52 being integral in rotation and arranged to be driven in rotation coaxially along the axis 22 to wind the first spring 8 and to be fixed during the unwinding of said first spring 8. The first winding wheel 52 is mounted at the end of the first barrel shaft 10, on the side of the bottom 3a of the first drum 3, preferably by driving in order to limit the play of said first drum 3.

There is also provided a second device for winding the second barrel 2 comprising a second winding wheel 54 coaxial along the axis 22 with the second barrel 2, the second barrel shaft 20 and the second winding wheel 54 being integral in rotation and arranged to be driven in rotation coaxially along the axis 22 to arm the second spring 18 and to be fixed during the disarming of the said second spring 18. The second winding wheel 54 is mounted at the end of the second shaft barrel 20, on the side of the bottom 12a of the second drum 12, by driving on the second barrel shaft 20. It is also possible to provide a free assembly with a square portion to guarantee the transmission of torque.

The first and second winding wheels 52, 54 are more specifically of the ratchet type and cooperate respectively in a known manner with a pawl to be immobilized in the direction of disarming of the spring 8, 18 corresponding. The first winding wheel 52 is preferably arranged to mesh with a crown wheel driven by the winding stem 56 of the base movement or with a pinion of an oscillating weight to wind the first barrel 1. The second winding wheel winding 54 can be arranged to mesh with a wheel of a winding train driven by another actuating member, such as another stem. Such winding mechanisms are known to those skilled in the art and do not require a more detailed description here.

In the variant shown, one of the first and second barrel shafts 10, 20 is pivotally mounted on the plate 30 and around which the other of the first and second barrel shafts 10, 20 is mounted free to rotate.

In another variant not shown, there may be provided a fixed central common shaft around which the first and second barrels 1, 2 are mounted to pivot freely, collars or any other arrangement being provided on the central common shaft to be able to carry barrel shafts 10, 20 freely in rotation.

More specifically, in the variant represented here, the two ends or pivots 10a, 10b of the first barrel arbor 10 are guided in a traditional manner in bearings or stones 60a, 60b respectively provided in the plate 30 and the bridge barrel 31 of the timepiece to allow the first barrel arbor 10 to rotate around the axis 22 relative to the plate 30 and the barrel bridge 31 fixed.

The bottom 3a of the first drum 3 has a central orifice 26 into which is inserted the barrel 52a of the first winding wheel 52 driven onto the end of the first barrel arbor 10. The bottom 3a of the first drum 3 is mounted to pivot freely around the barrel 52a of the first winding wheel 52.

In another variant not shown, the first winding wheel 52 does not include a barrel inserted in the central hole 26 of the bottom 3a of the first drum 3, and is driven directly onto the first barrel arbor 10. In In this case, the first drum 3 is mounted free to rotate directly around the first barrel arbor 10, a stone being able to be placed in the central orifice 26 of the bottom 3a, around the first barrel arbor 10.

The second barrel arbor 20 is hollow and mounted to pivot freely around the first barrel arbor 10. The second barrel arbor 20 is shortened, ending in its bung 20a, said bung 20a being arranged to rest on a surface of guide 62 provided around the first barrel shaft 10, above its bung 10c, when the two barrels 1, 2 are mounted superimposed, the inside of the drums 3, 12 facing each other. The second barrel arbor 20 is held in Z between the stone 60b and the guide surface 62 of the first barrel arbor 10. The height of the guide surface 62 as well as the thicknesses of the first and second springs 8, 18 are chosen to that the first and second springs 8, 18 are separated from each other by a small axial gap, the covers of the first and second barrels 1, 2 being removed. This interval prevents the turns of the first and second springs from intermingling. However, a single cover can be kept to separate the first and second springs 8, 18. A separation washer 42 can also be arranged in said gap maintained in guiding around the guide surface 62 of the first barrel shaft 10. The washer 42 can also be mounted on one of the first and second drums 3, 12 in the traditional manner by clipping. This separating washer 42 is preferably made of a material with a low coefficient of friction. It makes it possible to avoid friction between the first and second springs and to prevent their coils from becoming entangled. Its diameter is preferably at least equal to the diameter of the first and second drums 3, 12 in order to avoid friction also between the barrel drums.

The bottom 12a of the second drum 12 has a central hole 43 in which a stone can be placed, to allow the second drum 12 to rotate freely around the second barrel arbor 20. The second winding wheel 54 allows the maintenance in Z of the second drum 12.

According to another variant not shown, the ends of the peripheral walls of the first and second drums can be of complementary shapes to nest one inside the other while allowing the free rotation of the first and second drums one relative to each other without friction. Thus, the first and second drums together form a closed box containing the first and second springs 8, 18.

The present invention makes it possible to optimize the overall movement of the timepiece by combining two different types of regulating members, including an oscillator with flexible guidance, with two specific types of base and chronograph movements.

[0056] Furthermore, the use of a power source, of a mechanism comprising a specific gear train, and of a regulating organ dedicated to an auxiliary movement managing a complication, such as a chronograph, makes it possible to never disrupt basic movement.

In addition, the present invention makes it possible to optimize the size of two independent energy sources provided in the same timepiece. More particularly, the arrangement proposed by the present invention allows the two barrels to occupy a very compact volume, by eliminating at least one barrel cover (the first and second springs then being separated from each other by an interval ), an intermediate bridge, between the two barrels, as well as at least one of the pivots which would have been present during a simple superimposition of two barrels.

Thus, the use of two superposed independent barrels 1, 2 as well as their assembly with other elements (in particular the gear train of the mechanism 7, the chronograph gear train of the mechanism 17, the escapements 11, 21, the regulating organs 13, 15) of the first and second movements on the same side of the plate 30 makes it possible to optimize the arrangement of the two base and complication movements on the plate 30 and to obtain a timepiece comprising two independent movements , one regulated by a flexible-guided oscillator and the other by a spiral spring balance, on the same plate within the dimensions of a basic movement, while avoiding any chronometric influence between said mechanisms.

It is obvious that the present invention is not limited to the use of two superposed independent barrels, the number of superposed independent barrels possibly being greater than or equal to 2. Thus, it can be envisaged to superimpose three or four, or even more, independent barrels, as described above for two independent barrels, the corresponding mechanisms powered by these independent barrels being arranged accordingly around the superposed independent barrels.

[0060] Moreover, it is also quite obvious that in a variant embodiment not shown, the first barrel and the second barrel can be combined, the first and second movements then being supplied with energy by the same common barrel. The first and second kinematic chains can join for example at the level of the common energy source. The two regulating members can operate at the same frequency, said frequency being chosen to obtain optimal overall operation of the timepiece. The two regulating organs can also operate at different frequencies, as described above, provided that the common barrel can rotate at the same speed for the two kinematic chains. For example, two different toothings can be provided on the drum of the barrel of the common barrel.

Claims (13)

1. Timepiece comprising at least a first movement arranged to produce a first function and regulated by a first regulating member (13) and a second movement arranged to produce a second function and regulated by a second regulating member (15), characterized in that at least one of the first and second regulating members (13, 15) is a flexible guided oscillator. 2. Timepiece according to claim 1, characterized in that one of the first and second regulating members (13, 15) is an oscillator with flexible guidance and the other of the first and second regulating members is a spring balance. spiral. 3. Timepiece according to one of the preceding claims, characterized in that the first movement is a basic movement indicating the current time, the first regulating member (13) being a spiral spring balance and in that the second movement is an auxiliary movement, the second regulating member (15) being an oscillator with flexible guidance. 4. Timepiece according to claim 3, characterized in that the auxiliary movement is a chronograph movement. 5. Timepiece according to one of the preceding claims, characterized in that the first and second regulating members (13, 15) have different frequencies. 6. Timepiece according to one of claims 1 to 4, characterized in that the first and second movements are powered by the same common barrel. 7. Timepiece according to one of claims 1 to 5, characterized in that the first movement is powered by a first barrel (1) comprising a first drum (3), a first barrel arbor (10) around which the first drum (3) is rotatably mounted, and a first spring (8) housed in the first drum (3), said first movement constituting a first kinematic chain and the second movement is powered by a second barrel (2) comprising a second drum (12), a second barrel shaft (20) around which the second drum (12) is rotatably mounted, and a second spring (18) housed in the second drum (12), said second movement constituting a second kinematic chain independent of the first kinematic chain. 8. Timepiece according to claim 7, characterized in that it comprises a plate (30), and in that said first and second barrels (1, 2) are mounted superposed on said plate (30), the interior of the first and second drums (3, 12) facing each other and the first and second barrel shafts (10, 20) being coaxial. 9. Timepiece according to claim 8, characterized in that the first and second movements are mounted on said same plate (30). 10. Timepiece according to claim 9, characterized in that the first and second movements are mounted on the same side of said plate (30). 11. Timepiece according to one of claims 7 to 10, characterized in that it comprises a first winding device for the first barrel (1) comprising a first winding wheel (52) integral in rotation with the first barrel arbor (10) and a second device for winding the second barrel (2) comprising a second winding wheel (54) integral in rotation with the second barrel arbor (20). 12. Timepiece according to claim 11, characterized in that one of the first and second barrel shafts (10, 20) is pivotally mounted on the plate (30) and around which the other of the first and second shafts barrel (10, 20) is mounted free to rotate. 13. Timepiece according to one of claims 7 to 12, characterized in that the first and second barrels (1, 2) have no cover, the first and second springs (8, 18) being separated from one on the other by an axial interval.