Abstract:
Automatic mechanical winding device for the driving spring of a mechanical clockwork of a wristwatch with an eccentric mass that can be swiveled on a joint, said mass having a center of mass that is radially offset from the axis of the joint, with gear means for converting the swivel or rotary motion of the eccentric mass into a motion that winds the driving spring.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    The invention relates to a mechanical automatic winding device or spring winding device for the driving spring or watch spring of a mechanical clockwork of a wristwatch (automatic winding watch) and to a wristwatch with such a winding device. 
         [0002]    Wristwatches with a mechanical clockwork and with an automatic winding device that winds the driving spring or watch spring when the wristwatch is moved are known in the art. The winding device in such watches generally consists of an unbalanced mass or eccentric mass that is located on the back of the clockwork and can be swiveled on a central clockwork axis, the swivel motion being converted by a gear array into a rotary motion that winds the clockwork spring. 
         [0003]    A disadvantage of such mechanical automatic winding watches is that the shaft forming the swivel joint for the eccentric mass also serves to support this mass. In the event of jolts, vibrations or similar shock loads to the wristwatch, the forces occurring on the eccentric mass have to be absorbed by this shaft, which can easily result in damage to the watch. 
         [0004]    Also known is the use of balls as the eccentric mass in mechanical winding devices for wristwatches, the balls being provided in a circular ball guide enclosing the clockwork, namely between fingerlike pushers that extend into the ball guide and are provided on a swivel arm, which is rotatably mounted on the clockwork on the same axis as the clockwork axis and the rotary motion of which is converted via a gear unit into a motion for winding the driving spring of the clockwork. 
         [0005]    The disadvantage of this is that the ball guide for the balls forming the eccentric mass extends over an angle area of 360°, so that the space required for the ball guide results in a relatively high overall height and/or a relatively large diameter for the watch case. 
         [0006]    It is an object of the invention is to present a mechanical automatic winding device for wristwatches (automatic winding watches) that eliminates the aforementioned disadvantages while featuring a high degree of operational reliability and enables a reduced size of the watch or the watch case. 
       SUMMARY OF THE INVENTION 
       [0007]    The invention relates to an automatic mechanical winding device for the driving spring of a mechanical clockwork of a wristwatch with an eccentric mass that can be swiveled on a joint, the mass having a center of mass that is radially offset from the axis of the joint, with gear means for converting the swivel or rotating motion of the eccentric mass into a motion that winds the driving spring. 
         [0008]    Further embodiments, advantages and possible applications of the invention are disclosed by the following description of exemplary embodiments and the drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]    The invention is described in more detail below based on exemplary embodiments as referred to in the drawings, wherein: 
           [0010]      FIG. 1  is a simplified depiction of the back of a wristwatch with the back cover opened, together with the essential functional elements of the winding device; 
           [0011]      FIG. 2  is a perspective view of the back of the wristwatch of  FIG. 1 , with the housing partially opened; 
           [0012]      FIG. 3-4  are component drawings of a crescent-shaped swivel lever of the mechanical winding device of the wristwatch in  FIGS. 1 and 2 , manufactured from flat material; and 
           [0013]      FIG. 5-6  are schematic representations of further mechanical winding devices according to the invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0014]    In the drawings,  1  generally designates a wristwatch with the usual case  2 , in which the mechanical clockwork  3  is accommodated, namely in the depicted embodiment symmetrically, i.e. in the manner that the axis of the set-hands arbor of the clockwork is on the same axis as the middle axis of the case  2 . On the back of the clockwork  3  is the automatic mechanical winding device  4 , which causes the spring of the clockwork  3  to wind when the wristwatch  1  is moved, namely by means of a ratchet wheel  5  connected with a spring housing not depicted in the drawings, which (ratchet wheel) is mounted on the spring housing and can rotate on an axis  6  parallel to the clockwork axis or to the axis of the set-hands arbor of the clockwork  3 . 
         [0015]    The winding device  4  comprises in addition to the ratchet wheel  5  a crescent-shaped swivel lever  7 , which is manufactured form a suitable flat metal material, namely with a circular arc lever section  7 . 1 , which is curved on an axis parallel to the axis of the set-hands arbors, and with a lever section  7 . 2  extending radially to the curvature axis and in the depicted embodiment bent several times, extending radially inward from the section  7 . 1  (see also  FIGS. 3 and 4 ). The section  7 . 1  is provided on a partial section starting form the end located distant from the section  7 . 2  with two projections  8  and  9 , of which the projection  8  is provided on the free end of the section  7 . 1  and the projection  9  is provided at a distance from the free end of the section  7 . 1 . Each of the two projections  8  and  9  is provided with a slide or guide element  10 , e.g. in the form of a sliding element or roller, which is mounted to freely rotate by means of a ball bearing on an axis radial to the curvature axis of the section  7 . 1  or radial to the middle axis of the clockwork  3  or to the axis of the set-hands arbors of the clockwork. Between the two projections  8  and  9 , above the convex side of the section  7 . 1  facing away from the section  7 . 2 , two further projections  11  and  12  are provided, on which a circular arc mass weight  13  is fastened. The mass weight  13  consists of two circular segment curve single weights  13 . 1  and  13 . 2 , which are manufactured identically from a metal material with a high specific density, i.e. with a density greater than 14 g/cm 3 , for example of gold or platinum, and fastened on both sides on the partial section of the lever  7  formed between the projections  8  and  9  with screws extending through holes in the projections  11  and  12 . 
         [0016]    The lever  7  is fastened with the free end of the section  7 . 2  to a disk  14 , which itself is mounted on bearings so that it can rotate or swivel on a journal  15  on an axis parallel to the clockwork axis or parallel to the axis of the set-hands arbors on a bottom plate  16  of the clockwork  3 , namely for a back and forth rotary or swivel motion of the lever  7 , as indicated in  FIG. 1  by the double arrow A. 
         [0017]    Two pawl levers  17  and  18  that engage with the ratchet wheel  5  are mounted on the disk  14 , each pawl lever being manufactured with a formed-on leaf spring, for example by laser cutting from a suitable flat metal material and engaging through these springs with their free blade- or pawl-shaped ends with the gear teeth of the ratchet wheel  5 . The pawl levers are hinged on the disk  14  on different sides of an imaginary connecting line between the axis  6  of the ratchet wheel and the axis of the journal  15 , so that when the lever  7  is swiveled on the axis of the journal  15 , the ratchet wheel  5  is turned alternately via the two levers  17  and  18 , therefore winding the clockwork  3 . As a result of the use of two pawl levers  17  and  18  and of the described array of these levers or their hinge points on the disk  14 , a motion of the ratchet wheel  5  that winds the spring of the clockwork  3  takes place in each phase of the swivel motion of the ratchet wheel  5 , i.e. both during clockwise swiveling of the lever  7  and counterclockwise swiveling of the lever  7 , advantageously by a pulling force exerted via the pawl lever  17  or  18 . 
         [0018]    A recess is formed in the case  2  for accommodation of the two-part mass weight  13 . The recess  19  is larger than the length of the mass weight, so that a swivel motion of the mass weight  13  and therefore of the lever  7  on the axis of the journal  15  is possible, namely for example over a maximum path of 1.5-3 mm, for example a maximum path of 2.5 mm and preferably 1.5 mm. To support the mass weight  13 , the two slide or guide elements  10  that are offset in relation to the ends of the mass weight  13  are guided in guides  20  formed in the case  2 . 
         [0019]    To prevent noise during swiveling of the mass weight  13 , absorbing springs  21  are provided on the projections  8  and  9 , which (springs) engage with stop or limiting surfaces in the recess  19 . 
         [0020]      FIG. 5  shows a simplified view of a further embodiment of an automatic mechanical winding device  4   a  of a clockwork for a wristwatch, which (winding device) winds the spring of the clockwork when the wristwatch is moved, namely via a ratchet wheel  30 , which is provided on the spring housing of the clockwork. Two pawl levers  31  and  32  engage with this ratchet wheel, which (pawl levers) are hinged eccentrically on a gear  33  and  34  at  31 . 1  and  32 . 1 , respectively, namely so that they can swivel on axes parallel to the axis  30 . 1  of the ratchet wheel  30  and parallel to the axis  33 . 1  and  34 . 1  of the respective gear  33  and  34 . Due to spring means, which in the depicted embodiment consist of a bow spring  35 , the free ends of the pawl levers  31  and  32  engage spring-controlled with the gears of the ratchet wheel  30 . Further, the two gears  32  and  34  are connected with each other in a driven manner via their gear teeth. 
         [0021]    The gearwheel  33  comprising the pawl lever  31  is connected in a driven manner with an eccentric or mass weight or rotor  36 , which is mounted so that it can swivel on an axis  37  parallel to the clockwork axis or parallel to the axis of the set-hands arbors of the clockwork and in the depicted embodiment comprises a gearwheel  38  that engages with a gearwheel  33 , so that swiveling of the mass weight  36  on the axis of the shaft  37  via the gearwheel  38  produces a back and forth or swivel motion of the gearwheels  33  and  34  on their axes  33 . 1  and  34 . 1 , resulting in a rotation of the ratchet wheel  30  via the pawl levers  31  and  32  and therefore winding of the spring of the clockwork in each phase of this swivel motion, i.e. both during clockwise and counterclockwise swiveling. 
         [0022]    To achieve this, the winding device  4   a  is designed with gearwheels  33  and  34  of the same size and the gearwheels and the pawl levers  31  and  32  are arranged mirror symmetrically to an imaginary line L, which intersects the axes of the ratchet wheel  30  and also the axis of the shaft  37 . Further, in the initial position of the mass weight  36 , the hinge points of the pawl levers  31  and  32  are provided on the corresponding gearwheels  33  and  34  on the side of the axis  33 . 1  and  34 . 2  of the corresponding gearwheel  33  and  34  facing away from the line L and the free ends of the ratchet wheels  31  and  32  engage in the teeth of the ratchet wheel  30  on two diametrically opposing sides of the ratchet wheel  30  in relation to the line L. Further, in this embodiment, the pawl lever  31  or its end engaging with the ratchet wheel  30  exerts a pulling force on the ratchet wheel  30  to turn this wheel and, inversely, the pawl lever  32  exerts a pushing force with its end on the ratchet wheel  30  to turn this wheel. 
         [0023]      FIG. 6  shows a very schematic view of a further embodiment of an automatic mechanical winding device  4   b  of a clockwork for a wristwatch, which (winding device) winds the spring of the clockwork when the wristwatch is moved and which largely corresponds to the winding device  4   a  with respect to its function and design. For this reason, elements in  FIG. 6  that correspond to the elements of the winding device  4   a  are designated with the same reference numbers as in  FIG. 4   a.    
         [0024]    The winding device  4   b  differs from the winding device  4   a  initially in that instead of the pawl lever  31  and  32 , pawl lever pairs or pawl lever arrays, respectively consisting of two pawl levers  39  and  40  are provided, which have a leaf spring or bow spring effect and which are hinged respectively on an end at  39 . 1  and  40 . 1  on the gearwheel  33  and  34  and are supported with their other end on guides  41  provided on the base plate. A further difference from the winding device  4   a  is that instead of only one single ratchet wheel  30 , two such wheels  30  are provide one above the other on the same axis, namely with differing orientations of their ratchet teeth. On each pawl lever  39  and  40  a pawl is provided so that the pawl engages on a pawl lever  39  and  40  with the a ratchet wheel  30  and the pawl on the other pawl lever  39  and  40  engages with the other ratchet wheel  30  due to the spring effect of the respective pawl lever, so that each swivel motion of the mass weight  36  contributes to a rotary motion of the shaft comprising the ratchet wheels  30  and therefore winds the spring of the clockwork. 
         [0025]    The invention was described above based on exemplary embodiments. It goes without saying that numerous modifications and variations are possible without abandoning the underlying inventive idea on which the invention is based. 
         [0026]    For example, it is possible to use, instead of the circular segment mass weight  36 , another mass weight, for example the mass weight  13  provided on the lever  7 , in which case then the lever  7  is mounted with the free end of its lever section  7 . 2  on the gearwheel  38  so that it can swivel or rotate on the shaft  37 . 
       REFERENCE LIST 
       [0000]    
       
           1  wristwatch 
           2  case 
           3  clockwork 
           4 ,  4   a ,  4   b  winding device 
           5  ratchet wheel 
           6  rotary axis of the ratchet wheel 
           7  lever 
           7 . 1 ,  7 . 2  lever section 
           8 ,  9  projection 
           10  roller 
           11 ,  12  projection 
           13  mass weight 
           13 . 1 ,  13 . 2  weight element 
           14  disk 
           15  pivot 
           16  bottom plate 
           17 ,  18  pawl 
           17 . 1 ,  18 . 1  formed on bow spring 
           19  recess 
           20  guide 
           21  absorbing spring 
           30  ratchet wheel 
           30 . 1  axis of the ratchet wheel 
           31 ,  32  pawl lever 
           31 . 1 ,  31 . 2  link point of the pawl lever 
           33 ,  34  gear 
           33 . 1 ,  34 . 1  gear axis 
           35  bow spring 
           36  mass weight 
           37  shaft 
           38  gear on mass weight  36   
           39 ,  40  pawl lever 
           39 . 1 ,  40 . 1  end of pawl lever 
           41  guides 
         L line