Abstract:
A timepiece with a tourbillon unit, including a base plate, cage placed rotatably on the base plate and being connected to a fourth pinion, a balance placed on the cage, and an escape wheel that is placed on the cage and that is in work connection with the balance, a balance stop device being capable to be brought into engagement with the balance, wherein it further includes a zero-setting device for the angular orientation of the cage.

Description:
[0001]    This application claims priority from European Patent Application No 15183133.6 filed Aug. 31, 2015, the entire disclosure of which is hereby incorporated herein by reference. 
       TECHNICAL AREA 
       [0002]    The present invention relates to a mechanical clockwork movement with a tourbillon and so to a mechanical watch fitted with such. 
       BACKGROUND 
       [0003]    Tourbillons for mechanical clocks and clockwork movements are well-known. Here, the escape wheel, the pallets and the so-called balance of the clockwork movement are carried by a mobile cage which is coupled to or has a fixed connection with the shaft of the fourth wheel, and thus to the fourth pinion. The balance or staff coincides here typically with an imaginary axis extension of the fourth pinion. A toothed wheel connected to the escape wheel finally meshes with a fixed toothed wheel coaxial with the staff so that the tourbillon, thus its cage, makes one complete revolution per minute. 
         [0004]    For an exact setting of a mechanical watch, it is necessary to stop the indication of seconds. With conventional clockwork movements, this is made mostly by a so-called balance stop, which for example is activated by pulling out the crown and can be deactivated by pushing back the crown wheel. 
         [0005]    Watches with a minute-tourbillon, having an indication of seconds being made by the mobile cage of the tourbillon, the implementation of such a balance stop turns out to be extremely difficult and complicated. 
         [0006]    A balance stop for a tourbillon is well-known, for example from EP 2 793 087 A1. It is performed by a braking-element which can be brought into engagement with the staff and is movable coaxial with the latter. To match the watch with a standard time, it is therefore possible to stop the balance, and thus the tourbillon mechanism at any time. 
       SUMMARY OF THE INVENTION 
       [0007]    By contrast it is as object of the present invention to provide an improved balance stop for a tourbillon of a mechanical watch. In addition to a stopping of the tourbillon, a zero-setting of the tourbillon for easy time setting is to be realized. This is to improve the operability and time setting of the watch and also give the watch an increased functional scope. 
         [0008]    This object is solved by a clockwork movement having a tourbillon unit according to the independent patent claim  1  and by a watch having such a clockwork movement according to patent claim  15 . Advantageous embodiments in this respect are subject of the dependent patent claims. 
         [0009]    In this respect a clockwork movement of a mechanical watch is provided with a tourbillon unit. The clockwork movement has a base plate which carries all moving components of the clockwork movement. The clockwork movement, especially its tourbillon unit, further comprises a cage connected to a fourth pinion being rotatable mounted on the base plate and a balance mounted on the cage. An escape wheel which is in work connection with the balance is also mounted on the cage in addition to the balance. The escape wheel is typically in work connection with the balance via pallets. Balance, pallets and escape wheel herewith build the escapement of the mechanical clockwork movement. The fourth pinion is typically coupled with an energy store, for example a barrel, which finally drives the clockwork movement. 
         [0010]    The clockwork movement is further provided with a balance stop device that can engage the balance. By means of the balance stop device, the balance can be at least temporarily fixed relative to the base plate or relative to the cage to stop the clockwork movement. Furthermore, the clockwork movement is provided with a zero-setting device that allows the angular orientation of the cage to be set in a predetermined position that preferably corresponds to the zero position of a seconds hand attached to the cage. According to a preferred embodiment, the zero-setting device can be optionally torque-proof engaged with the cage or with the base plate. The zero-setting device is typically torque-proof connected to the base plate of the watch in normal operation. 
         [0011]    This means that the zero-setting device is fixed relative to, or directly on, the base plate whereas the cage, together with the entire tourbillon unit, is exposed to a rotational movement relative to the base plate. When the clock movement is stopped, especially for setting the time, the zero-setting device is also detachable from the base plate or can be pivotally decoupled so that it can be pivotated relative to the base plate. It typically engages to the cage in a torque-proof manner. The zero-setting device therefore always either engages the cage in a torque-proof manner or the base plate or the zero-setting device even engages both the cage and the base plate in a torque-proof manner. 
         [0012]    It is possible to decouple the cage for setting the time at least temporarily from the energy storage device of the clockwork movement by using the option of torque-free engaging the zero-setting device with the base plate or the cage. Using an alternating fixing or torque-proof connection to the zero-setting device with the cage or base plate, it is possible for the zero-setting device, together with the cage, to create a zero-stop function, also for example under the influence of the mechanical energy storage of the movement but decoupled from the minutes or hours pinion of the clockwork movement, is transferable to a defined zero-setting. 
         [0013]    The optional engagement of the zero-setting device with the cage or with the base plate can be achieved by successive and stepwise pulling-out of a crown, for example a winding or setting crown of the clockwork movement. According to a preferred embodiment of the claimed clockwork movement, the crown can be in three different axial positions, i.e. is a first so-called rest position in which for example the mainspring can be wound up as usual by the crown, in a second position at which the balance is stopped, e.g. according to the solution of EP2793087 and in a third axial position where the zero-setting device is no longer engaged with the base plate, but with the cage. Then, at this third position of the crown, the zero-setting device and the cage as a complete unit can be pivoted by the clockwork via the seconds pinion, and thus the zero setting of the cage takes place automatically, wherein the minutes hand setting can be provided by turning the crown at this position. Preferably, a minutes ratcheting may further be present incl. hands friction in a minute wheel group similar to that in Patent EP2224294; the tourbillon unit and the zero-setting device according to the preset invention are compatible with that—thanks to permanent engagement between the minute wheel, third wheel and second pinion. 
         [0014]    According to a further design, it is provided that the zero-setting device is torque-proof fixed to the base plate in a basic configuration. In the basic configuration, the crown is in a basic position in which the clockwork movement is driven by a mechanical energy store. The zero-setting device acts as a type of base for the tourbillon unit by its fixing to the base plate. Particular provision can be made that the tourbillon unit, or a part thereof, is in work connection with the zero-setting device. In the basic configuration at a zero-setting device fixed to the base plate, this acts solely as a support for further mechanical components of the clockwork movement, for the tourbillon unit or individual components thereof for example. 
         [0015]    According to a further embodiment, the zero-setting device is torque-proof coupled to the cage by means of the balance that has been stopped by the balance stop device. In the basic configuration, the cage can pivote freely relative to the base plate. This means, that the cage only pivotes relative to the base plate under influence of the escapement and under influence of the mechanical driving energy from the barrel. As soon as the cage is stopped by the balance stop device and fixed relative to the base plate, the zero-setting device can be either indirectly or directly coupled to the cage in a torque-proof manner. 
         [0016]    It is conceivable that zero-setting device and balance stop device have such a mutual interaction that the zero-setting device is torque-proof coupled to the cage by activating the balance stop device. It is also conceivable that the zero-setting device already has a fixed connection with the balance stop device. Fixing of the cage relative to the base plate by means of the balance stop device leads in this respect also inevitably to a torque-proof fixing of the cage relative to the zero-setting device. 
         [0017]    By a direct or indirect coupling between zero-setting device and cage, it is possible for example to torque-proof connect the zero-setting device to the cage for the purpose of adjusting the clockwork movement. By means of the zero-setting device, the cage fixed to it can be returned to a defined zero position from any position in which the cage has been stopped, the zero position being such that a seconds hand on the cage points to the zero. 
         [0018]    According to a further embodiment, the balance stop device comprises a braking element located axial movable to a balance axis on the rotating cage and frictionally engaged with the balance. A balance stop can be realized using such a braking element which does not exert any radially asymmetric forces on the balance or on the rotating cage of the tourbillon. The balance can also be braked immediately via such a braking element, especially stopped. A braking and stopping of the balance also leads inevitably to a stop of the rotational movement of the tourbillon, i.e. the rotational movement of the rotating cage is stopped. 
         [0019]    Because of the axial mobility of the braking element, this can for example be engaged for braking with an axially directed end face of the balance or with a section fixed to the balance, for example a double roller torque-proof connected to the balance. The balance can therefore be directly or indirectly braked and stopped so that post-oscillations of the balance when activating the balance stop are not to be feared. The balance stop device is especially suitable for implementing a balance stop for a flying tourbillon as the balance stop device only affects the balance in the axial direction. 
         [0020]    Due to the frictional interaction between braking element and balance, it is also possible to increase the frictional force applied to the balance by activating the braking element abruptly or continuously. The latter in particular enables a damped, oscillation-free stopping of the balance. A frictional braking of the balance wheel also enables the stopping of the balance in any orientation or position of the balance. 
         [0021]    According to a further embodiment, the zero-setting device can be torque-proof coupled to the cage via the braking element. The zero-setting device can in particular influence directly or indirectly the braking element mounted on the cage. The zero-setting device, but at least individual components or parts of this can in particular lie in the power transmission path of the balance stop device. 
         [0022]    According to a further embodiment, the zero-setting device can be fixed torque-proof to the base plate using a fixing element. By means of the fixing element, the zero-setting device can either be fixed torque-proof to the base plate or released from it so that the zero-setting device can be pivoted relative to the base plate. 
         [0023]    It is also provided here, that the fixing element is only transferable to a released position if the cage and the zero-setting device are coupled torque-proof, a released position in which the zero-setting device together with the cage can be rotated relative to the base plate. As the fixing element can only be transferred to a release position after a torque-proof coupling of cage and zero-setting device has been made, it is possible to prevent the driving force of the mechanical energy storage device of the clockwork movement being released in an uncontrolled manner. 
         [0024]    If the cage is coupled to the zero-setting device and the fixing element is transferred to the release position, a typical, if applicable, damped rotational movement of the cage and zero-setting device combination takes place, wherein the rotating cage has an operative connection to the energy storage device of the clockwork movement via the activated balance stop device. The seconds pinion of the tourbillon is also in this configuration, as before, in mechanical work connection with the energy storage device of the clockwork movement, with the barrel for example. 
         [0025]    According to a further embodiment, further a locking latch is movably located on the base plate. This interacts with a catch mechanism located on the cage to stop the cage at zero position. The locking latch can for example be transferred radially inwards to a locking position in which it interacts with the catch mechanism of the cage so that a rotational movement of the cage beyond the locking latch or past the locking latch is prevented. 
         [0026]    The catch mechanism can for example protrude radially outwards from the cage. If the locking latch is for example located in a radial inwards shifted locking position and the zero-setting device together with the cage is the subject of a rotational movement at a fixing element in the release position, the catch mechanism of the cage engages with the locking latch. The locking latch therefore acts as end stop for the catch mechanism and so for the cage so that this comes to rest in the zero position provided for the setting of the clockwork movement. 
         [0027]    According to a further embodiment, the locking latch is coupled to the fixing element. The locking latch only moves into a locking position to stop the cage when the fixing element passes from the fixing position to the release position. The locking latch and the fixing element are rigidly coupled together in this respect. If the combination of cage and zero-setting device are released for a pivotal movement, the locking latch moves radially inwards in order to stop the free pivotal movement of the combination at a fixed predetermined position. 
         [0028]    The mutual arrangement of catch mechanism and locking latch therefore defines the zero-position of the cage and therefore the seconds hand of the tourbillon unit located on the cage. 
         [0029]    According to a further embodiment, the zero-setting device has a support wheel with a rim-type circumferential band. The circumferential band is rotatably mounted at its outer circumference on at least three support rollers arranged on the base plate. The zero-setting device has a ring-type basic geometry as a special feature. In a final assembly configuration of the clock movement, the hub of the tourbillon unit usually occupies the free center of the ring of the zero-setting device. By means of a mounting via the outer periphery on the support wheel, the zero-setting unit can also be rotated on the base plate independent of the tourbillon unit. 
         [0030]    According to a further embodiment, the zero-setting device has a ring-type circulating wheel with inner teeth which mesh with a pinion of the escape wheel. The circulating wheel of the zero-setting device which is also fixed relative to the base plate in the basic configuration or when the clockwork is in motion, meshes with the escape wheel. The escape wheel moves, especially due to the teeth of its pinion with the inner teeth along those, in case the tourbillon unit is subjected to a rotary motion being predominant when the clockwork is in operation. In the basic configuration, the zero-setting device acts in this respect as an extended baseplate along whose inner teeth the escape wheel with its pinion runs. 
         [0031]    According to a further embodiment of the clockwork movement, the zero-setting device has a stop ring which is movable along its axis of rotation. This has a start slope on a radially outer-lying edge that corresponds to the start slope of a movable stop latch located on the base plate. Two diametrically opposed escapement stopping latches are normally provided. These can be moved radially inwards in direction to the stop ring by pulling out the crown. 
         [0032]    The stop ring experiences an axial movement due to the mutually corresponding and matching start slopes of stop ring and stop latch or stop latches, when the stop latch or stop latches are moved radially inwards. By means of the mutually corresponding start slopes of stop ring and stop latch or stop latches, a radial movement can be so translated into an axial movement. 
         [0033]    According to a further embodiment, each movable stop ring mounted axially on the zero-setting device has a further start slope at a radial inner-lying edge that interacts with at least one cam that moves radially inwards against a restoring force at the latch mounted on the zero-setting device. In this way, that latch can be radially swiveled by an axial shift of the stop ring relative to the zero-setting device, especially relative to the at least one axially adjacently mounted latch. 
         [0034]    In particular at least one latch of the zero-setting device can be actuated radially inwards by means of the at least one latch of the zero-setting device induced axial movement of the stop ring. Due to the mutual engaging of stop latch, stop ring and latch of the zero-setting device, it is possible that a pivoting movement acting radially from outside on the zero-setting device is converted into a radial inwards swivel movement of the latch provided at the zero-setting device. 
         [0035]    According to a further embodiment, the at least one latch has a start slope at its inner radial end, that can be engaged with the start slope of a brake ring. The brake ring is typically arranged axially adjacent to the latch and can also be shifted axially on a main axis of the tourbillon unit relative to the zero-setting device, for example mounted on the hub of the tourbillon unit. In that the at least one latch and the brake ring engaged with it have start slopes corresponding to each other, the typically radial, inwards pointing pivot or shift movement of the latch can be translated into an axial directed displacement of the brake ring. 
         [0036]    According to a further embodiment, it is finally intended that an axially movable brake bolt is guided in a hub of the tourbillon unit or in the cage and can be axially displaced for the displacement of the brake element and for causing the balance to stop by means of the brake ring. The brake bolt is displaceable especially against a restoring force, especially against the effect of a spring element axial to the brake ring. The brake bolt deflects especially the brake element which is movable axial to the balance wheel axis such that it engages the balance by friction or by a friction-fit and brings the balance finally to a stop. 
         [0037]    At the zero-setting device, usually not only one latch is provided but several, about three, equidistantly spaced to each other, which due to an axial movement of the neighboring stop ring perform a synchronous, radially inwards directed movement. Correspondingly, an as uniform and symmetrical as possible displacement force can be exerted on the brake ring which finally leads to an axial advance of the brake bolt. 
         [0038]    Finally, according to a further aspect a timepiece, especially a mechanical wrist watch, being fitted with a previously described clockwork mechanism, is provided. 
     
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         [0039]    Further objects, features and advantageous embodiments are explained in the following description of an embodiment example with reference to the drawings. The figures show: 
           [0040]      FIG. 1  a top view of parts of the clockwork movement 
           [0041]      FIG. 2  a side view of the clockwork movement according to  FIG. 1 , 
           [0042]      FIG. 3  a perspective view of the clockwork movement, 
           [0043]      FIG. 4  a plan view from below of the zero-setting device in the base configuration with a stop ring removed, 
           [0044]      FIG. 5  a cross section of the zero-setting device according to  FIG. 4 , 
           [0045]      FIG. 6  a plan view of the zero-setting device from above, 
           [0046]      FIG. 7  a view of the zero-setting device according to  FIG. 4 , however with radially inwards displaced latches, 
           [0047]      FIG. 8  a cross section of the zero-setting device according to  FIG. 7 , 
           [0048]      FIG. 9  a plan view from above of the zero-setting device according to  FIG. 7 , 
           [0049]      FIG. 10  an exploded view of the zero-setting device, 
           [0050]      FIG. 11  a cross section A-A according to  FIG. 6  in a final assembled configuration with a tourbillon unit, 
           [0051]      FIG. 12  a cross section B-B according to  FIG. 9 , also with tourbillon unit, 
           [0052]      FIG. 13  a perspective and partly-exploded view of the clockwork movement in the base configuration and 
           [0053]      FIG. 14  a view of the clockwork movement of  FIG. 13 , however with activated balance stop device and with a zero-setting device in the release position. 
       
    
    
     DETAILED DESCRIPTION 
       [0054]      FIGS. 1 to 3  show a tourbillon unit  10  of a mechanical clockwork movement  1 , here partially shown. The clockwork movement  1  has a base plate  2  on which the tourbillon unit  10  is rotatably placed. The tourbillon unit  10  is, as can be seen from  FIGS. 2 and 11 , coupled to a third wheel  7  via a seconds pinion  5 . The third wheel  7  meshes with a minutes wheel  8 , which engages a barrel  9 , which here acts as a mechanical energy storage device. 
         [0055]    The tourbillon unit  10  further comprises a hub  6  shown in a cross-section in  FIG. 11 , which is rotatably placed on the base plate  2  and is fixed to a cage  11  of the tourbillon unit  10 . 
         [0056]    The cage  11  comprises a lower frame  11  a with diverse radially arranged spokes  11   d  which join the cage  11  to the hub  6 . Here, three vertical, axially directed pillars  11   c  are arranged around the outer circumference of the lower frame  11   a . An upper frame  11   b  is placed on the end section of the far side of the lower frame  11   a . The balance  15  of the movement  1  is placed between the upper and lower frames  11   a ,  11   b . The balance  15  can be pivoted relative to a balance axis  17 , wherein the balance axis  17  is located on an extension of the seconds pinion  5 . 
         [0057]    The balance  15  is also coupled to a balance spring  16 . An escapement  14  is also provided at the cage  11 . An escape wheel  12  is rotatably placed on the cage  11 . The axis of rotation of the escape wheel  12  extends parallel to the balance axis  17 . The escapement  14  also has a not explicitly shown pallets which engage alternately with the teeth of the escape wheel  4  in the well-known manner. The balance  16 , the not explicitly shown pallets and the escape wheel  12  form the escapement  14 . 
         [0058]    As follows from the cross-section of  FIGS. 11 and 12 , the escape wheel  12  is fitted with a pinion  19  which meshes with the inner teeth  49  of a zero-setting device  40 . The zero-setting device  40  is fixed to the base plate  2  during normal operation of the clockwork movement  1 . The step-by-step rotational movement of the escape wheel  12  therefore leads to a rotation of the entire cage  11  relative to the base plate  2 . Further a seconds hand  18  is located on the cage  11  with the tip of the hand protruding radially outwards from cage  11 —upper frame  11   b  in the present case. The rotational position of the cage  11  therefore passes on the seconds to a time indicator. 
         [0059]    Apart from the zero-setting device  40 , the clockwork movement  1  has a balance stop device  50  which is used to stop the balance  15  if required. 
         [0060]    The multi-part structure of the zero-setting device  40  is made clear in  FIGS. 4 to 10 . The zero-setting device  40  has a carrier wheel  41  with a central passage  71 . The carrier wheel  41  has a ring-shaped contour. The central passage  71  is bordered in particular by an inner edge  72 , as indicated in  FIG. 4 . Three latches  45  arranged over the circumference of the inner edge  72  protrude radially inwards from the inner edge  72 . These are mounted and can be rotated or pivoted in the plane of the carrier wheel  41 . They can be displaced radially inwards, as a comparison of  FIGS. 4 and 7  makes clear. 
         [0061]    Each of the latches  45  has a control! start slope  45   a  at its free and inwards protruding end. A dome-shaped latch cam  47  is formed on the underside of the latches  45 . Each of the latches  45  is also coupled to a latch spring  46  by means of which the individual latches  45  can be displaced radially inwards against a spring force. The radially directed displacement inwards takes place via an axial force applied to the latch cams  47 . If the force reduces, the individual latch springs  46  effect a movement of the latches  45  radially outwards to the start position as shown in  FIG. 4 . 
         [0062]    On the radially outer edge of the carrier wheel  41  of the zero-setting device  40  is, as shown in  FIG. 5 , formed a circular rim  44 . The carrier wheel  41  has an outer toothing  48  axially offset to this. A circular wheel  42  is located on the upper side of the carrier wheel  41 . The circular wheel  42  also has a ring-shaped contour. On an inner side of the circular wheel  42  circumferential inner teeth  49  are formed, which, as already mentioned, mesh with the pinion  19  of the balance  15 . 
         [0063]    A stop ring  43  is located on the underside of the carrier wheel  41 . The stop ring  43  has an outer start slope  53  on its outer edge. The stop ring  43  mounted on the carrier wheel  41  can also be axially displaced. The stop ring  43  also possesses, as shown in  FIG. 5 , a further start slope  54  on its inner edge. 
         [0064]    With the torque-proof connection and the axial slideability of the stop ring  43  and carrier wheel  41 , the inner start slope  54  of the stop ring  43  engages the latch cam  47 . An upwards axial movement of the stop ring  43  up to the carrier wheel  41  therefore effects a radial inwards displacement of the three latches  45 . This can be recognized by comparing  FIGS. 5 and 8  or  FIGS. 6 and 9 . 
         [0065]    The entire zero-setting device  40  is rotationally mounted on the base plate  2  via the circular rim  44  with a plurality of rotatable mounting rollers  31  distributed over the circumference of the zero-setting device  40 . The zero-setting device  40  can also be fixed to, but also detached from, base plate  2  using a fixing element  30  which is formed here as a fixing lever. A free end of the fixing element  30  engages, for example frictionally, with an outer edge of the zero-setting device  40 . 
         [0066]    By pivoting of the fixing element  30  the zero-setting device  40  can be released so that it can be rotated relative to base plate  2  about a central axis of rotation  73 . The axis of rotation  73  of the zero-setting device  40  can coincide in particular with the balance axis  70  as well as with the axis of the seconds pinion  5 . 
         [0067]    Furthermore, a braking element  60  is mounted on the upper side of the lower frame  11   a , here in the form of a flat brake spring. The braking element  60 , especially its free and radially inwards protruding end, is located axially movable on the cage  11 . In particular, it can be moved by means of an axially slidable brake bolt  58 , either in the hub  6  or on the cage  11  from a starting position as shown in  FIG. 11 , to a braking position as shown in  FIG. 12 . 
         [0068]    The brake bolt  58  is located with a head in a recess of the lower frame  11   a . By means of an axial, upwards directed movement, the braking bolt  58  presses axially on the braking element  60  so that its free end engages frictionally and in the axial direction with a correspondingly designed friction surface of a double roller  62 , which is connected to the balance  15 . In this way, the balance  15  can be stopped and fixed relative to the cage  11 . 
         [0069]    The brake bolt  58  can be transferred from the starting or base position shown in  FIG. 11  to the brake position shown in  FIG. 12  by means of the axially movable mounted brake ring  56 . Radial external and at the lower end, the brake ring  56  has a start slope  56   a , which is circumferentially formed and designed to correspond to the regulating start slope  45   a  of the latches  45 . A radially inwards directed pivot movement of the latches  45  therefore leads to an upwards axial shift of the brake ring  56  in direction to the cage  11  by which the brake bolt  58  and therefore also the brake element  60  is axially displaced or axially shifted. Due to the radial inwards pivot movement of the latches  45 , the brake element  60  finally engages with the double roller  62  of the balance  15 . 
         [0070]    The axial displacement of the brake ring  56  relative to the hub  6  or relative to the cage  11  takes place against the restoring force of a expander spring  57 , which is located axially between the hub  6  and the brake ring  56 . If for example, the latches  45  under the influence of their respective latch springs  46  are pivoted back into the starting position shown in  FIG. 4 , a movement of the brake ring  56  also takes place under the influence of the expander spring  57  in the same way to its starting position shown in  FIG. 11 . As a consequence, the balance  15  is again released causing the stopped clockwork movement  1  to be self-actingly set in motion again. 
         [0071]    To stop the clockwork movement  1  and the tourbillon unit  10 , respectively two first and second opposing stop latches  20  and  22  are provided on the outer circumference of the zero-setting device  40  as can be seen in  FIG. 13 . The first stop latch  20  and the second stop latch  22  are pivoting mounted on the base plate. A first start slope  21  and a second start slope  23  are provided at their free ends. These are designed, for example, in the form of beveled small wheels. Respectively the first and second start slopes  21  and  23  of the relevant first and second stop latches  20  and  22  are located at the height of the outer start slopes  53  provided on the outer edge of the stop ring  43 . 
         [0072]    A radial inwards pivoting of the first and second stop latches  20 ,  22  leads to a uniform raising or axial displacement of the stop ring  43  from the starting position or base configuration shown in  FIG. 11  to the stop configuration shown in  FIG. 12 . For the sake of simplicity, the position of the first and second start slopes  21 ,  23  are not explicitly shown in  FIGS. 11 and 12 . The axial movement of the stop ring  43  leads, as already described, to a radially inwards directed displacement of the latches  45  and therefore to an axial shift of the braking bolt  58  and finally to a displacement of the braking element  60  stopping the balance  15 . 
         [0073]    A synchronous displacement movement of both first and second braking latches  20 ,  22  causing a stopping of the clockwork mechanism  1  can take place by pulling out the crown to a given ratchet position. This stops the clockwork movement  1 . If the crown, here not explicitly shown, is pulled out starting from that stop configuration to a further, for example second ratchet position, a coupled pivoting of the fixing element  30 , and of a locking latch  26  is effected. 
         [0074]    It is initially intended here that the locking latch  26  shown in  FIG. 13  is moved radially inwards so that a locking catch  27  protruding radially inwards at the free end of the locking latch engages with a catch mechanism  28  located on the outer circumference of the cage  11 . In this respect, the locking latch  26  can be transferred from its start position in  FIG. 13  to an indicated catch position in  FIG. 14 . In this, the locking latch  26  prevents the cage  11  with its catch mechanism  28  rotating beyond the position of the locking catch  27 . 
         [0075]    In the course of the zero-setting procedure, the cage  11  can be rotated freely while mounted on the base plate  2 . Due to the mutual engagement of locking latch  26  and catch mechanism  28 , a defined end stop for the cage  11  is therefore generated for the entire tourbillon unit  10  so that the seconds hand  18  comes typically to rest at the twelve. Once the locking latch  26  has clicked into its catch position, the fixing element  30  engaged with the zero-setting device  40  is displaced radially outwards in the course of the pulling-out movement of the crown. Thus, the zero-setting device  40  is transferred to a release position so that its rotary fixing relative to base plate  2  is nullified. 
         [0076]    The coupled movement of locking latch  26  and fixing element  30  is initiated by control lever  24  as indicated in  FIG. 13 . The pivoting movements of the fixing element  30  and of the locking latch  26  are rigidly coupled together. It is necessary to ensure that the fixing lever  30  can only be transferred to its release position when the locking latch  26  is in its catch position. 
         [0077]    When setting the timepiece, for example, the regulating lever  24  is moved by pulling a crown out of the base position to a first pull-out position, this effects a radial inwards pivoting of both first and second stop latches  20 ,  22 . As a consequence the balance  15  is stopped. This fixes the balance  15  on the cage  11  or the hub  6 . In each configuration, the cage and the zero-setting device  40  form a combination which can be rotated relative to the base plate  2 . 
         [0078]    In a next step the locking latch  26  gets into the further catch position indicated in  FIG. 14  when the crown is pulled out to the next catch position. Finally in a last step, the fixing element  30  is transferred to the release position so that the ensemble of zero-setting device  40  and cage  11  can be rotated via the mounting rollers  31  relative to the base plate  2 . The seconds pinion  5  of the tourbillon unit  10  remains here in engagement with the barrel  9 . The still remaining flow of forces between the tourbillon unit  10  and the barrel  9  effects that the cage  11  together with the zero-setting unit  40  rotates until the catch cam  28  engages with the locking latch  26 . 
         [0079]    In this axial position of the crown, the seconds hand  18  therefore automatically reaches a well-defined zero-position without any further action being necessary at the crown. The usual interaction between a zero-setting lever and a usual zero-setting flyback is therefore no longer necessary. As the zero setting of the seconds hand  18  takes place via a combined rotational movement of zero-setting device  40  and tourbillon unit  10  driven by the barrel via the seconds drive  5 , this rotational movement can be preferably damped or braked using a separate braking mechanism. This braking mechanism not explicitly shown here can, for example, permanently engage with of the outer teeth  48  of the zero-setting device  40 . This braking device can, for example, act as a rotational damper. It can, for example, comprise a so-called wind vane that limits the free rotational motion of the zero-setting device  40  to a preset maximum speed. According to a preferred embodiment, not shown here, the rotational damper is made as a hydraulic damper module which meshes with the outer teeth  48  of the zero-setting device  40  via an intermediate wheel. In this way, the gear ratios in this gear wheel train as well as the viscosity of the liquid in the hydraulic damper module can be set to achieve an adjusted rotational speed. 
         [0080]    The beveled first and second start slopes  21 ,  23  are used, in addition to the mounting rollers  31 , for the radial and axial mounting of the zero-setting device  40  on the base plate  2 . 
         [0081]    If the crown of the clockwork movement  1  is again moved back stepwise, the fixing element  30  is initially engaged frictionally with the zero-setting device  40 . The locking latch  26  is then returned from its catch position back to a starting position. As a consequence, the zero-setting device  40  is on the one hand refixed to the base plate  2  while the cage  11  disengages with the locking latch  26 . 
         [0082]    To set the clockwork movement  1  automatically in motion again, it is only necessary by a further inwards movement of the crown to move the two first and second stop latches  20 ,  22  radially outwards again. As a consequence, the force on the stop ring decreases. This is returned in particular by the latch springs  46  and the mutual engagement between latches  45  and stop ring  43  to its starting position shown in  FIG. 5 . At the same time an axial displacement of the braking ring  56  to its starting position under the influence of the expansion spring  57  takes place. The brake bolt  58  therefore reaches its starting position and the braking element  60  releases the double roller  62  of the balance  15 . 
         [0083]    Due to the interaction of the zero-setting device and the balance stop device  50 , it is possible for the first time to move an entire tourbillon unit  10  independently of the escapement  14  in the clockwork movement  1  in a controlled manner. That independent movement enables a tourbillon unit  10  to be moved faster and automatically to a reference point in any conceivable position. This option is especially suitable for a so-called minutes tourbillon, which serves simultaneously as a seconds hand. In this respect, a seconds zero stop is provided for a setting procedure of the clockwork movement  1 . 
         [0084]    It is especially advantageous here that no radial forces act on the tourbillon unit, neither when the balance wheel  15  is stopped nor during the zero-setting procedure. The escapement  14  is namely stopped and therefore protected against external influences during the zero setting operation. Furthermore, the here-shown embodiment of the zero-setting device  40  with the balance stop device  50  enables a small constructional change to an existing flying tourbillon, as known for example from EP 2 793 087 A1. 
       LIST OF REFERENCE NUMBERS 
       [0085]      1  Clockwork movement 
         [0086]      2  Base plate 
         [0087]      5  Fourth pinion 
         [0088]      6  Hub 
         [0089]      7  Third wheel 
         [0090]      8  Minutes wheel 
         [0091]      9  Barrel 
         [0092]      10  Tourbillon unit 
         [0093]      11  Cage 
         [0094]      11   a  Lower frame 
         [0095]      11   b  Upper frame 
         [0096]      11   c  Pillar 
         [0097]      11   d  Spoke 
         [0098]      12  Escape wheel 
         [0099]      14  Escapement 
         [0100]      15  Balance 
         [0101]      16  Balance spring 
         [0102]      17  Balance axis 
         [0103]      18  Seconds hand 
         [0104]      19  Pinion of the escape wheel 
         [0105]      20  First stop latch 
         [0106]      21  First start slope 
         [0107]      22  Second stopping latch 
         [0108]      23  Second start slope 
         [0109]      24  Control lever 
         [0110]      26  Locking latch 
         [0111]      27  Locking catch 
         [0112]      28  Detent cam 
         [0113]      30  Fixing element 
         [0114]      31  Mounting roller 
         [0115]      40  Zero-setting device 
         [0116]      41  Carrier wheel 
         [0117]      42  Circular wheel 
         [0118]      43  Stop ring 
         [0119]      44  Circular rim 
         [0120]      45  Latch 
         [0121]      45   a  Start slope 
         [0122]      46  Latch spring 
         [0123]      47  Latch cam 
         [0124]      48  Outer teeth 
         [0125]      49  Inner teeth 
         [0126]      50  Balance stop device 
         [0127]      53  Outer start slope 
         [0128]      54  Inner start slope 
         [0129]      56  Brake ring 
         [0130]      56   a  Start slope 
         [0131]      57  Expander spring 
         [0132]      58  Brake bolt 
         [0133]      60  Brake element 
         [0134]      62  Double roller 
         [0135]      71  Passage 
         [0136]      72  Inner edge 
         [0137]      73  Axis of rotation