Abstract:
A clockwork movement includes a mechanical energy source, a first regulating part and a first escapement, which are connected by a first gear-train to the energy source, and a second regulating part and a second escapement, which are connected by a second gear-train to the energy source. The first gear-train, the first escapement ( 4 ) and the first regulating part ( 2 ) define a first assembly. The second gear-train, the second escapement and the second regulating part ( 10 ) define a second assembly. At least one differential gear is arranged to provide a kinematic connection between the first assembly and the energy source and between the second assembly and the energy source.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is the United States national phase of International Application No. PCT/EP2014/069053 filed Sep. 8, 2014, and claims priority to Swiss Patent Application No. 01697/13 filed Oct. 3, 2013, the disclosures of which are hereby incorporated in their entirety by reference. 
     BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The present invention relates to a timepiece movement, in particular for a mechanical timepiece. More specifically, it relates to a timepiece movement comprising:
         a mechanical energy source,   a first regulating organ and a first escapement linked by a first gear train to said energy source, the first gear train, the first escapement and the first regulating organ defining a first ensemble,   a second regulating organ and a second escapement linked by a second gear train to said energy source, the second gear train, the second escapement and the second regulating organ defining a second ensemble, and   a differential gear arranged to provide a kinematic link firstly between the first ensemble and the energy source and secondly between the second ensemble and the energy source.       

     The present invention also relates to a timepiece comprising such a movement. 
     Description of the Related Art 
     A similar movement is in particular described in patent CH 698622. This type of movement incorporating two regulating organs powered by the differential gear described in patent CH 698622 or any other differential gear known from the prior art has certain unwanted effects related to the use of such a differential gear. In particular, when there is a simultaneous impulse on both kinematic chains, one comprising the first ensemble and the other comprising the second ensemble, the energy is first supplied to the kinematic chain that requires least energy. Only after this has occurred will the second chain receive energy. This results in that the energy used to keep the regulating organ of the second chain going is lost. Indeed, since the impulse has already been applied to the regulating organ, the anchor is already in the idle phase. This results in a reduction in the amplitude of the second balance and an increase in the amplitude of the first balance, which has a negative impact on running of the timepiece. 
     One objective of the present invention is therefore to mitigate this drawback by proposing a timepiece movement that immediately provides each of the two regulating organs with the energy it requires, without disturbing the other regulating organ. 
     SUMMARY OF THE INVENTION 
     For this purpose, and according to the present invention, a timepiece movement is proposed, comprising:
         a mechanical energy source,   a first regulating organ and a first escapement linked by a first gear train to said energy source, the first gear train, the first escapement and the first regulating organ defining a first ensemble,   a second regulating organ and a second escapement linked by a second gear train to said energy source, the second gear train, the second escapement and the second regulating organ defining a second ensemble, and   at least one differential gear arranged to provide a kinematic link firstly between the first ensemble and the energy source and secondly between the second ensemble and the energy source.       

     According to the invention, said movement furthermore comprises:
         a first spring organ provided between the differential gear and the first escapement and arranged to exert torque on a first output of the differential gear,   first means for re-charging said first spring organ,   a second spring organ provided between the differential gear and the second escapement, arranged to apply torque to a second output of the differential gear, and   second means for re-loading said second spring organ.       

     The spring organs enable each of the two regulating organs to be immediately supplied with the energy it requires without disturbing the other regulating organ by eliminating the losses or the surplus energy caused by the differential gears known from the prior art. 
     Preferably, the differential gear may comprise a first transmission wheel and a first output wheel mounted freely in rotation and linked kinematically to the first ensemble, said first spring organ having a first extremity linked to said first output wheel and a second extremity linked to said first transmission wheel. 
     Preferably, the differential gear may comprise a second transmission wheel and a second output wheel mounted freely in rotation and linked kinematically to the second ensemble, said second spring organ having a first extremity linked to said second output wheel and a second extremity linked to said second transmission wheel. 
     Advantageously, the first means for re-loading the first spring organ may include a first driving for the first output wheel, said first driving means being rigidly connected to the first transmission wheel. 
     Advantageously, the second means for re-charging the second spring organ may include second driving means for the second output wheel, said second driving means being rigidly connected to the second transmission wheel. 
     Advantageously, the differential gear may include an input wheel linked kinematically to the energy source. 
     Preferably, the input wheel may carry at least one satellite pinion arranged to cooperate with each of the first and second transmission wheels. 
     Advantageously, each of the first and second spring organs may be a spiral spring. 
     The present invention also relates to a timepiece comprising a movement as described above. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will be better understood from the following description, of an embodiment, provided as an example, with reference to the drawings, in which: 
         FIG. 1  is a schematic overview of a movement according to the invention, 
         FIG. 2  is an isometric view of the differential gear and of the spring organs used in the invention, and 
         FIG. 3  is a cross-section view of  FIG. 2 , 
     
    
    
     DESCRIPTION OF THE INVENTION 
     With reference to  FIG. 1 , the timepiece movement according to the invention includes in particular:
         a mechanical energy source  1 , such as a barrel,   a first regulating organ  2  and a first escapement  4  comprising a first escapement wheel  5  and a first anchor  6 , linked by a first gear train  8  to said energy source  1 , the first gear train  8 , the first escapement  4  and the first regulating organ  2  defining a first ensemble,   a second regulating organ  10  and a second escapement  12  comprising a second escapement wheel  13  and a second anchor  14 , linked by a second gear train  16  to said energy source  1 , the second gear train  16 , the second escapement  12  and the second regulating organ  10  defining a second ensemble,   a differential gear  18  arranged to provide a kinematic link firstly between the first ensemble and the energy source  1  and secondly between the second ensemble and the energy source  1 .       

     In the variant shown here, the regulating organs  2  and  10  are simple balances, but it is obvious that they could also be tourbillons or carousels. Furthermore, the first and second escapements shown are Swiss lever escapements, although they could be of another type, such as detent escapements or another known type of escapement. 
     With specific reference to  FIGS. 2 and 3 , the elements making up the differential gear are mounted pivotingly about a shaft  20  rigidly connected to the frame of the movement. 
     The differential gear  18  includes an input wheel mounted pivotingly about the shaft  20  and having external toothing that meshes with an intermediate wheel  24  that in turn meshes with the energy source  1 . It is obvious that the mechanism may include other wheels in addition to the intermediate wheel  24  between the differential gear  18  and the energy source  1 . 
     The input wheel  22  is rigidly connected to a satellite carrier  26  that has shafts  28  perpendicular to the shaft  20 , upon each of which is mounted pivotingly a satellite pinion  30 . In the variant shown, the satellite pinions  30  have conical toothing. 
     The differential gear  18  also includes a first transmission wheel  32  and a second transmission wheel  34 , respectively mounted pivotingly about the shaft  20  by means of a cannon wheel  33  and  35  respectively. The first and second transmission wheels  32 ,  34  each have conical toothing arranged on either side of the satellite pinions  30 . The conical toothing of the first and second transmission wheels  32 ,  34  is designed to mesh with the conical toothing of the planetary gears  30 . 
     The first and second transmission wheels  32 ,  34  shown here are bell wheels, but it is obvious that any transmission wheel of a flat differential may be used. Equally, the shape of the toothing of the planetary gears and of the toothing of the transmission wheels is adapted to the structure of the differential. In particular, the toothings may be straight. 
     The differential gear  18  also includes a first output wheel  36  and a second output wheel  38 , respectively mounted freely in rotation about the shaft  20 , and positioned outside the first and second transmission wheels  32 ,  34  respectively. 
     The first output wheel  36  has an external toothing meshing with the first gear train  8  and the second output wheel  38  has an external toothing meshing with the second gear train  16 . 
     A first pin  40  is force fitted into the first transmission wheel  32  and inserted with clearance into a hole provided in the first output wheel  36 . Equally, a second pin  42  is force fitted into the second transmission wheel  34  and inserted with clearance into a hole provided in the second output wheel  38 . The role of these pins  40 ,  42  is described below. 
     According to the invention, the movement furthermore comprises:
         a first elastic or spring organ  44  provided between the differential gear  18  and the first escapement  4  and charged to exert torque on the first output wheel  36 ,   a second elastic or spring organ  46  provided between the differential gear  18  and the second escapement  12  and charged to exert torque on the second output wheel  38 .       

     More specifically, the first spring organ  44  is positioned outside the first output wheel  36 , opposite the first transmission wheel  32 , concentric to the shaft  20 . It has a first extremity  48  rigidly connected to the first output wheel  36  by means of a pin  50  and a second extremity  52  rigidly connected to the cannon wheel  33  of the first transmission wheel  32 . 
     Equally, the second spring organ  46  is placed outside the second output wheel  38  opposite the second transmission wheel  34 , concentric to the shaft  20 . It has a first extremity  54  rigidly connected to the second output wheel  38  by means of a pin  56  and a second extremity  58  rigidly connected to the hour wheel  35  of the second transmission wheel  34 . 
     The first and second spring organs can be pre-charged during construction of the movement. 
     In another structural variant not shown, the first spring organ  44  may be placed inside the first output wheel  36 , on the same side as the first transmission wheel  32 , and the second spring organ  46  may be placed inside the second output wheel  38 , on the same side as the second transmission wheel  34 . 
     In the variant shown, the spring organs  44  and  46  are spiral springs. 
     Naturally, other variant embodiments are possible, such as replacing the spring and the related output wheel with a wheel incorporating an elastic element. The spring organs or elastic elements may be of any shape (coil, spiral, leaf, etc.) and made of any material, the shape and material being chosen so that said spring organs or elastic elements can store and return energy. 
     The movement according to the invention functions as follows: 
     During operation, the motive force supplied from the energy source  1  enters the differential gear  18  via the intermediate wheel  24 , the input wheel  22  and the satellite carrier  26  carrying the satellite pinions  30 . 
     When the first and second anchors  6  and  14  release the escapement wheels  5  and  13  respectively, the related output wheels  36  and  38  respectively transmit torque to the respective gear train  8  and  16 . Since the spring organs  44  and  46  are pre-charged on their associated output wheels  36  and  38 , these latter keep turning as long as they have the possibility. The output wheels  36  and  38  start moving before the transmission wheels  32  and  34 . Indeed, the output wheels  36  and  38  are closer to the escapements  4  and  12  than the transmission wheels  32  and  34 . Thus, since the force path is shorter to the output wheels  36  and  38 , these latter have a quicker reaction time than the transmission wheels  32  and  34 . 
     This mechanism makes it possible to transmit forces to the output wheels  36  and  38  that originate exclusively in the respective spring organs  44  and  46  of same. This transmission also occurs when the impulses from the regulating organs  2  and  10  are simultaneous. 
     Thus, each regulating organ  2  and  10  instantly receives the energy it requires without disturbing the other. As such, all of the unwanted effects found with the differential gears known in the prior art are eliminated, including when the impulses are simultaneous. 
     To enable the related spring organ  44 ,  46  to be recharged, the first and second transmission wheels  32 ,  34 , driven by the energy source  1 , recover their lags in relation to the respective output wheels  36 ,  38 . Thus, the initial torque of the spring organs  44  and  46  is restored. Furthermore, the pins  40 ,  42  act as stops for the transmission wheels  32  and  34  in the output wheels  36 ,  38  when recovering the lags, to ensure that the related spring organ  44 ,  46  is always recharged with the same torque. 
     The cycle can then be repeated. 
     Naturally, the present invention is not limited to the example embodiment described. Notably, the timepiece movement may include several differential gears arranged sequentially between a main differential gear, positioned closest to the energy source, and the escapement of the first and/or second ensemble. In this case, the first spring organ provided between the main differential gear and the first escapement may more specifically be positioned between the output of the main differential gear and the input of the next cooperating element, i.e. a second differential gear. Equally, the second spring organ provided between the main differential gear and the second escapement may more specifically be positioned between the output of the main differential gear and the input of the next cooperating element, i.e. a third differential gear.