Abstract:
A timepiece includes: a frame; a mobile body of a finishing gear train; and a tourbillon mechanism including a holder supporting a balance and at least one escapement. The tourbillon mechanism includes: an outer ring rotatably mounted onto the frame about a first axis; at least one inner ring inside the outer ring and rotatable relative to the outer ring about a second axis, the holder being pivotably mounted in the inner ring and secured to a shaft around which the inner ring is freely and rotatably mounted about a third axis; a first toothed member mounted onto the frame; a first pinion secured to the shaft of the holder to engage with the first toothed member to rotate the holder; and a unit driving the inner ring, engaging with the movable body of the finishing gear train and arranged to move the inner ring and, consequently, the outer ring.

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates to mechanical timepieces. It more particularly relates to a timepiece comprising a frame, at least one wheel of a going train and at least one tourbillon mechanism comprising a support, such as a carriage, supporting a balance and at least one element of an escapement. 
       BACKGROUND OF THE INVENTION 
       [0002]    A tourbillon mechanism is a device intended to average the running deviation of the positions of the balance of a timepiece. In the present invention, such a tourbillon comprises the traditional tourbillon comprising a tourbillon carriage as well as the karussel. To that end, a tourbillon includes a support (for example, a carriage in the case of the traditional tourbillon) pivotably mounted on the frame, in general an assembly formed by a bar and a plate and, pivotably mounted on the support, a sprung balance and an escapement in particular including an escapement wheel provided with a disc and a pinion. The support includes a gear kinematically connected to the going train of the timepiece, in general to the mean disc. A toothed wheel, mounted fixed on the frame, meshes with the escapement pinion. In this way, each time the balance is in position to receive a driving impulse from the escapement, the torque applied by the mean disc on the gear causes the support to rotate slightly, the impulse from the balance being given by the escapement whereof the wheel turns by meshing of its pinion with the toothed disc. The discs and pinions are generally arranged and numbered such that the tourbillon performs one revolution per minute. Thus, when the timepiece is positioned vertically, the position of the dead point of the balance therefore performs one revolution per minute, which averages the running deviations in the vertical positions. However, the lag between the horizontal and vertical positions remains. 
         [0003]    Different solutions have been proposed to offset this drawback. 
         [0004]    Known for example is a tri-axial tourbillon described in application EP 1,574,916, comprising a carriage containing the balance and the escapement rotating along an axis, the carriage being mounted in a second carriage so as to be able to rotate around the axis, the second carriage being rotatably mounted in turn in a third carriage rotating around a stationary axis relative to the timepiece, the three axes being perpendicular to one another. The tri-axial tourbillon is driven by a driving disc mounted on the plate of the timepiece, which drives a pinion secured to the third carriage, and causes the carriage to rotate around its axis, thereby setting a pinion in rotation meshing with a crown fixed on the plate of the timepiece, which rotates the carriage around its axis, the second carriage setting the first carriage in rotation around its axis by means of a crown and the fourth-wheel pinion secured to the third carriage, and thus to transmit the energy coming from the drive disc to the assembly formed by the escapement pinion, the escapement disc and the balance placed in the first carriage. 
         [0005]    Such a mechanism has the drawback of being bulky and not very aesthetically pleasing due to the presence of several toothed crowns appearing on the dial side. 
         [0006]    Also known is a differential correction device described in application EP 2,031,465. This device comprises several supports pivotably mounted around respective articulation axes, which makes it possible to neutralize the movements of a transmission train around two or more axes. The aim of this mechanism is to keep the seat of the support bearing the adjusting system in a constant position irrespective of the position of the frame. The isochronism faults of the system are eliminated, given that the oscillating system has only one position. Such a mechanism does not have the same aims as a tourbillon mechanism, which makes it possible to further reduce the running differences between horizontal and vertical positions of a timepiece comprising such a tourbillon mechanism. 
         [0007]    One aim of the present invention is therefore to offset these drawbacks, by proposing a timepiece comprising a tourbillon mechanism making it possible to further reduce the running differences between horizontal and vertical positions. 
         [0008]    Another aim of the present invention is to propose a timepiece comprising a tourbillon having a reduced bulk and improved aesthetic appearance. 
       BRIEF DESCRIPTION OF THE INVENTION 
       [0009]    To that end, and in accordance with the present invention, proposed is a timepiece comprising a frame, at least one wheel of a going train, and at least one tourbillon mechanism comprising a support bearing a balance and at least one element of an escapement. 
         [0010]    According to the invention, the tourbillon mechanism further comprises:
       an outer ring rotatably mounted on the frame around a first axis,   at least one inner ring mounted inside the outer ring and rotatable relative to the outer ring around a second axis, preferably perpendicular to the first axis, the support being pivotably mounted in the inner ring and said support being secured to an arbor around which the inner ring is mounted freely rotating along a third axis,   a first toothed organ, mounted on the frame,   a first pinion secured to the arbor of the support arranged to cooperate with said first toothed organ so as to rotate said support, and   means for driving the inner ring cooperating with a wheel of the going train and arranged to move the inner ring and the outer ring accordingly, giving the support a composite movement.       
 
         [0016]    This composite movement of the support makes it possible to further reduce the running differences between the horizontal and vertical positions, as described in patent EP 1,419,419. 
         [0017]    Advantageously, the means for driving the inner ring may comprise a driving element secured to an arbor of the disc of the going train. 
         [0018]    The first toothed organ may be securely fixed to the frame. This then creates a tourbillon mechanism. When the first toothed organ is not securely fixed to the frame, it is then a karussel mechanism as described in patent CH 7965. 
         [0019]    According to a first alternative, the driving element cooperates with the arbor of the support so as to impose a rotating movement thereon around the first toothed organ. 
         [0020]    According to a second alternative, the inner ring comprises a tube that is secured thereto, wherein the arbor of the support can rotate freely, the driving element cooperating with said tube so as to impose a rotational movement around the first toothed organ on the inner ring. 
         [0021]    Preferably, the arbor of the support forms a non-zero angle with the first toothed organ. However, in other alternative embodiments, said angle may be a non-zero angle. 
         [0022]    Advantageously, the tourbillon mechanism may further comprise a second toothed organ secured to the inner ring and arranged to cooperate with a second pinion kinematically connected to the escapement. 
         [0023]    According to different possible embodiments, the support may be positioned such that its axis of rotation is or is not perpendicular to the second axis of rotation of the inner ring relative to the outer ring. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0024]    The invention will be better understood upon reading the following description of different embodiments, provided as an example and done in reference to the drawings, in which: 
           [0025]      FIGS. 1 and 2  show perspective views of the tourbillon mechanism according to the invention, the outer ring respectively being in each of its maximal positions relative to its axis of rotation, 
           [0026]      FIGS. 3 and 4  show perspective views of the tourbillon mechanism according to the invention, the inner ring respectively being in each of its maximal positions relative to its axis of rotation, 
           [0027]      FIG. 5  shows a perspective view of the tourbillon mechanism of the invention, the outer ring and the inner ring being in intermediate positions, 
           [0028]      FIG. 6  is a cross-sectional view of the tourbillon mechanism according to the invention, and 
           [0029]      FIG. 7  is a cross-sectional view of a detail of another alternative embodiment of the tourbillon mechanism according to the invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0030]    In reference to  FIGS. 1 ,  2  and  6 , an alternative embodiment is shown of a tourbillon mechanism  1  according to the invention mounted on a frame  2  of a timepiece. Generally, the frame is an assembly formed by a bar and a plate, but of course the frame can comprise any support element for the organs of the timepiece. 
         [0031]    On the frame  2 , a wheel  4  of a going train is pivotably mounted, such as the mean disc. The wheel  4  comprises an arbor  6  on which a driving element  8  is securely mounted, bent and ending with a bracket  10 , the role of which will be described hereafter. 
         [0032]    Also mounted securely on the frame  2  is a first stationary disc  12 , around the arbor  6  of the wheel  4 . 
         [0033]    The tourbillon mechanism comprises a tourbillon carriage  14  bearing a balance  16 , a balance-spring  18  and an escapement, traditionally comprising an escapement disc  20  and an escapement pinion  22  pivotably mounted in a support organ  23  secured to the tourbillon carriage  14 . The other elements of the tourbillon carriage  14 , such as the pallet, are known by those skilled in the art and will not be described in more detail here. Of course, the invention also applies to a karussel mechanism, the tourbillon carriage then being replaced by a support bearing the balance and the escapement, and the disc  12  not being stationary, as described in patent CH 7965. 
         [0034]    Furthermore, in the illustrated alternative, the pallet and the escapement disc are loaded on the tourbillon carriage  14 . It is also possible for only the pallet to be loaded on the carriage, the escapement disc then being mounted stationary, as described in patent EP 2,132,604. 
         [0035]    According to the invention, the tourbillon mechanism further comprises:
       an outer ring  24  rotatably mounted on the frame around a first axis A 1 , using two pivots  24   a,    24   b,      an inner ring  26  mounted inside the outer ring  24  and rotatable relative to the outer ring  24  around a second axis A 2  perpendicular to the first axis A 1 , using two pivots  26   a,    26   b.          
 
         [0038]    In the present description, the term “ring” designates an element that surrounds another element, but does not necessarily have an annular shape. Thus, in the illustrated example, the outer ring  24  has an annular shape, while the inner ring  26  has a rectangular shape, comprising an upper part  26 ′ and a lower part  26 ″, connected by two side pillars  27 . Of course, the rings used in the invention may assume any other appropriate shape. 
         [0039]    The frame  2  has a recess, the shape of which is suitable for allowing pivoting of the tourbillon mechanism. 
         [0040]    Furthermore, the tourbillon carriage  14  comprises, secured to said tourbillon carriage  14 , an upper arbor  28  provided with a pivot  28   a  and a lower arbor  30  provided with a swivel  30   b.  The pivot  28   a  and the swivel  30   b  are respectively engaged in bearings  32 ,  34  of the inner ring  26 , such that the tourbillon carriage  14  is pivotably mounted in said inner ring  26 . The dimensions of the inner ring  26  are chosen such that the tourbillon carriage  14  can be housed therein and rotate freely therein. 
         [0041]    Furthermore, a second disc  36  is securely mounted on the inner ring  26 , coaxially to the arbor of the tourbillon carriage  14 . 
         [0042]    The escapement pinion  22  is positioned such that it meshes with the second wheel  36 , secured to the inner ring  26 . 
         [0043]    The lower arbor  30  is mounted passing through the lower part  26 ″ of the inner ring  26 , such that said inner ring  26  is mounted freely rotating around the lower arbor  30  along a third axis of rotation A 3 . More particularly, the lower part  26 ″ of the inner ring  26  comprises an annular base concentrically positioned around the lower arbor  30  and bearing the second wheel  36 , as shown in  FIG. 5 . 
         [0044]    The lower arbor  30  includes, at its free end, a first pinion  38  having a conical tubing and positioned such that it meshes with the first stationary disc  12 , secured to the frame. In the illustrated alternative, the stationary disc  12  is a toothed organ having an outer toothing. It is clear that the stationary disc may be replaced by a crown having an inner toothing. 
         [0045]    The lower arbor  30  has, at its free end, a pivot  30   a  engaged in a bearing  10   a  provided on the bracket  10  of the driving element  8 . Thus, the driving element  8  secured to the arbor  6  of the wheel  4  constitutes the means for driving the lower arbor  30  in which said lower arbor  30  is guided while forming a connection of the ball joint type. These means for driving the lower arbor  30  indirectly constitute the means for driving the inner ring  26 , as will be seen hereafter. 
         [0046]    In another alternative embodiment shown in  FIG. 7 , the inner ring  26  cooperates directly with the driving element  8 . To that end, the inner ring  26  includes a tube  40 , secured to its lower part  26 ″, coaxial to the lower arbor  30  of the tourbillon carriage  14 . The tube  40  is positioned around said lower arbor  30  such that the latter can rotate freely in the tube  40 . As in the first alternative, the lower arbor  30  includes a first pinion  38  meshing with the stationary disc  12 . In this alternative, it is the tube  40  of the inner ring  26  that operates directly with the bracket  10  of the driving element  8 . Thus, the driving element  8  secured to the arbor  6  of the wheel  4  constitutes the means for driving the inner ring  26  in which the tube  40  is guided while forming a connection of the ball joint type. 
         [0047]    Of course, the inner ring  26  may also be driven by its upper part, the driving element, the wheel of the going train, the arbor of the tourbillon carriage and the tube of the inner ring being provided on the side of its upper part  26 ′. 
         [0048]    The inner ring  26  is positioned such that the lower arbor  30  of the tourbillon carriage  14  forms a non-zero angle with the first stationary disc  12 , preferably comprised between 5° and 85°. 
         [0049]    In the illustrated alternative, the axis A 4  of the first stationary disc  12  is perpendicular to the frame  2 . The axis A 4  is combined with the axis of rotation of the wheel  4 . 
         [0050]    Of course, the axis of rotation of the wheel of the going train may not be perpendicular to the frame, the tourbillon mechanism then being positioned accordingly. 
         [0051]    In the illustrated alternative, the tourbillon carriage  14  is positioned such that its axis of rotation is perpendicular to the second axis of rotation A 2  of the inner ring  26  relative to the outer ring  24 . 
         [0052]    The third axis of rotation A 3  of the inner ring  26  around the lower arbor  30  of the tourbillon carriage  14  is preferably perpendicular to the second axis of rotation A 2  of the inner ring  26  relative to the outer ring  24 , which means that the axis of rotation of the tourbillon carriage  14  is combined with the third axis of rotation A 3  of the inner ring  26  around the lower arbor  30 . 
         [0053]    In the illustrated alternative, the balance axis is positioned coaxially to the axis of rotation A 3 . Of course, in other alternative embodiments that are not shown, the balance axis may be parallel to the axis of rotation A 3  or inclined such that it is not combined with the axis of rotation A 3  of the inner ring around the lower arbor of the tourbillon carriage. The pallet and the escapement wheel will be positioned accordingly. 
         [0054]    The tourbillon carriage and the upper and lower parts of the inner ring can then be arranged suitably, as for example described in patent EP 1,419,419. 
         [0055]    When the movement operates, the wheel  4  of the going train is animated by a rotational movement so as to subject the inner ring  26  to a motor torque by meshing with the first pinion  38 . In fact, when the wheel  4  is rotating, its arbor  6  is also able to pivot and rotate the driving element  8  with it. According to the first alternative, the lower arbor  30  guided in the bracket  10  of the driving element  8  is then able to rotate around the axis A 4 . According to the second alternative, it is the tube  40  guided in the bracket  10  of the driving element  8  which is then able to rotate around the axis A 4 , driving the rotational movement of the lower arbor  30  around the axis A 4 . During this movement, the first pinion  38  secured to the lower arbor  30  can mesh with the first stationary disc  12  such that the inner arbor  30  is also able to pivot around the axis A 3  to rotate the tourbillon carriage  14 . 
         [0056]    However, the motor torque can only create a movement of the lower arbor  30  and therefore the inner ring  26  if the first pinion  38  meshes with the first stationary disc  12 , and therefore if the tourbillon carriage  14  rotates around the axis A 3 . Since the escapement pinion  22  is engaged with the toothing of the second wheel  36 , that means that this movement is only possible when the escapement imparts a driving impulse to the balance. 
         [0057]    In the first alternative, when the lower arbor  30  moves, the latter being mounted inclined passing in the lower part  26 ″ of the inner ring  26 , said inner ring  26  must also move while remaining inclined, consequently driving the outer ring  24 , thereby imparting a composite movement to the tourbillon carriage  14 . In the second alternative, the inner ring  26  is directly driven by the driving element  8 . Due to this composite movement, the pivots  26   a,    26   b  of the inner ring  26  perform an alternating rotational movement perpendicular to the axis A 1  of the outer ring  24 . The inner ring  26  tilts around its pivots  26   a,    26   b  while being driven by the outer ring  24  and by the lower arbor  30  or directly by the driving element  8 . 
         [0058]    At the same time, the lower arbor  30  is rotated around the axis A 3  by its pinion  38  meshing with the first stationary disc  12 . The rotation of the lower arbor  30  drives the rotation of the tourbillon carriage  14  and therefore of the escapement pinion  22 . The latter meshes with the second disc  36  to drive the rotation of the escapement disc  20 , the latter cooperating with a pallet to maintain the movement of the balance  16 . 
         [0059]      FIGS. 1 and 2  show views in which the outer ring  24  respectively occupies a maximal position relative to its axis of rotation A 1 . 
         [0060]    Other positions of the tourbillon mechanism are shown in  FIGS. 3 to 5 , the same elements being shown with the same references. 
         [0061]      FIGS. 3 and 4  show the tourbillon mechanism in which the inner ring  26  respectively occupies its maximal position relative to its axis of rotation A 2 , and  FIG. 5  shows the tourbillon mechanism in which the outer ring  24  and the inner ring  26  occupy intermediate positions relative to those shown in the figures. 
         [0062]    In the illustrated alternative, the movement of the axis of rotation A 3  of the inner ring  26  relative to the axis A 4  generates at least one frustoconical enclosure. 
         [0063]    The composite movement obtained by the tourbillon mechanism according to the invention makes it possible to decrease the time spent by the balance in unfavorable positions. Furthermore, using two rings makes it possible to decrease the inertia relative to a traditional tourbillon carriage. 
         [0064]    Additionally, the tourbillon mechanism according to the invention is such that it comprises at least 4 pivot points instead of 2 in a traditional tourbillon, such that the impact resistance of the tourbillon mechanism according to the invention is increased. 
         [0065]    Of course, the present invention is not limited to the described embodiment. In particular, the shape of the rings may vary. It is also possible to provide other inner rings arranged relative to one another such that none of them are floating. It is also possible to provide a fly carriage in which the pivoting of the inner ring only occurs on the side of the carriage that is rotated.