Patent Publication Number: US-6902169-B2

Title: Sealed crown for watch casing

Description:
BACKGROUND OF THE INVENTION 
     The present invention has for its object a sealing device for a control member passing through the wall of a watch casing such as a setting crown or a pushbutton for example. 
     SUMMARY OF THE INVENTION 
     The object of the present invention is to provide a sealed device for a control member passing through the wall of a watch casing, which permits ensuring normal sealing, for example resistant to 10 Atmospheres, during use of the control member and increased sealing when the control member is not used, for example resistant to 100 Atmospheres. 
     Another object of the present invention is to avoid, during passage from normal sealing to increased sealing, any angular and/or axial movement of the control member to avoid any interaction with the control mechanism. 
     Still another object of the invention is the provision of such a sealing device which will be simple to produce and to mount and which can be easily dismounted by post-sale service, for example to change the seals. 
     The present invention has for its object a sealing device for a control member passing through a watch casing, which overcomes the drawbacks of the existing devices and permits achieving the objects set forth above, this sealing device being distinguished by the characteristics set forth below. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings show schematically and by way of example three embodiments and two modifications of the sealing device according to the invention. 
         FIG. 1  is a cross-sectional view of the sealing device in the increased sealing position. 
         FIG. 2  is a cross-sectional view of the sealing device in the normal sealing position, for actuating the control member. 
         FIG. 3  is a bottom view of the compression key. 
         FIG. 4  is a side view of the compression key. 
         FIGS. 5 and 6  are cross-sectional views on the line A—A of  FIG. 4  in the open position, respectively the closed position of the compression key. 
         FIG. 7  shows in cross-section a second embodiment of the sealing device. 
         FIG. 8  shows in cross-section a third embodiment of the sealing device. 
         FIGS. 9 and 10  show in cross-section modifications in the shape of the embodiment shown in FIG.  8 . 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The present sealing device for a control member passing through a casing, in particular a watch casing, is applicable also to pushbuttons which more particularly have a setting shaft or crown. This device permits considerably increasing the sealing of the control member. With the help of this device, normal sealing of about 10 Atmospheres which is present during manipulations of the control member can be increased to a value of the order of 100 Atmospheres by a simple manipulation of a compression key, which manipulation also immobilizes the control member in its inactive position. 
     Moreover, as will be seen later, this sealing device is easy to produce and to mount on a sealed casing because it comprises only few pieces that are easy to machine. Moreover, the after sale service is simplified because dismounting the device, particularly to change the seals, can take place easily without returning to the factory by a watchmaker present at the point of sale. 
     The sealing device according to the present invention is shown in the accompanying drawings in relation to the sealing of a setting crown and comprises a tube  1  comprising an internal cylindrical portion and an external cylindrical portion of larger diameter provided with a screw thread  2 . In its lower portion, this tube  1  comprises a cylindrical bore whilst in its upper portion the tube  1  has a central conical opening flaring toward the outer end of the tube  1 . 
     The internal cylindrical end of smaller diameter is forcibly driven into a bore  3  passing through the sealed casing  4 . Below the screw threads  2  of the tube  1  there is an annular throat in which is disposed an O-ring joint  5  coacting with this tube  1 , with the external surface of the casing  4  and, as will be seen later, with the compression key  6 . 
     The compression key  6  of the first embodiment shown in  FIGS. 1  to  6  comprises a body provided with an internal screw thread corresponding to the screw thread  2  of the tube and screwed on the latter. This body is provided with a sleeve  7  whose internal surface coacts with the joint  5  and with an upper portion  8  having the shape of a crown whose lower surface has a conical portion. The body of this compression key  6  moreover comprises two external wings  9  permitting its manipulation by the user. 
     Thus, when the tube  1  is driven into the bore  3  of the casing  4  and the compression key  6  is screwed onto this tube, the joint  5  ensures sealing between the compression key  6  and the tube  1  and protects the screw threading  2 . Moreover, this joint  5  ensures a certain friction between the tube  1  and the compression key such that the latter will not move untimely, but only under the effect of a couple which the user can impose on it. 
     As seen in  FIGS. 3 ,  5  and  6 , the sleeve  7  of the compression key  6  is milled about 180° of its periphery so as to create two abutments  10 ,  11  adapted to coact with the head of a screw  12  screwed into the watch casing and thus limiting the rotation of the compression key to about 180°. The periphery of the compression key  6  comprises a recess  13  permitting access to the screw head  12  to install and remove it when dismounting the sealing device and replacing the seals. 
     Screw  12  constitutes a stop coacting with the abutments  10 ,  11  of the compression key to limit the rotation of the latter between an open position and a closed position. 
     The sealing device moreover comprises a split ring  14 , preferably of Delrin or of steel, of conical shape, disposed in the narrow portion of the internal cone of the tube  1 . On this ring  14  is disposed an O-ring joint  15  whose upper portion bears against the lower surface of the upper portion  8  of the compression key. 
     In the open position, unscrewed, of the compression key  6 , this joint  15  is only partially compressed ( FIG. 2 ) whilst in the closed position, screwed in, of the compression key, this joint  15  is totally compressed ( FIG. 1 ) between the upper portion  8  of the compression key, the tube  1 , the ring  14  and the shaft  16  of the crown  17 . 
     The setting crown  17  comprises a shaft  16  passing through the upper portion  8  of the compression key  6 , the ring  14  and the cylindrical portion of the tube  1 . The end of the shaft  16  of the crown  17  is provided with two O-ring joints  18 ,  18 ′ disposed in a circular throat provided in the external cylindrical wall of the shaft  16 . These joints  18 ′ ensure normal sealing of the order of 10 Atmospheres, between the tube  1  and the shaft  16  when the compression key is open. In this position, the user can actuate the setting shaft  16  axially and in rotation. 
     When the compression key is screwed in or closed, the joint  15  is totally compressed and forces the split ring to the bottom of the cone of the tube  1  and against the setting shaft  16 . In this position, the sealing is very substantially increased and reaches a value of 100 Atmospheres and the shaft  14  is blocked. 
     The shaft  16  of the setting crown comprises, in the usual way, an axial screw thread  19  in its internal end permitting coupling to the setting shaft properly so called of the mechanism. 
     Thanks to this sealing mechanism, there is achieved a high sealing, 100 Atmospheres, in the closed position of the compression key and the setting shaft is blocked. The watch can be worn in this position and it is only during setting of the time of the movement that the user frees the compression key to permit this function. In this open position, the sealing is nevertheless guaranteed at a normal value of the order of 10 Atmospheres. 
     A supplemental advantage of the sealing device resides in the fact that during passage from the open position to the closed position of the compression key and vice versa, the shaft  16  of the crown  17  undergoes no axial displacement which could damage the mechanism. 
     Moreover, if the screw pitch used to screw the compression key onto the tube comprises a left hand thread, when a user tightens the compression key, even if the user simultaneously turns the crown  17 , as he might accidentally do, the mechanism cannot be damaged. Thus, the rotation for tightening the compression key takes place in the reverse direction of the rotation of the crown  17  for setting the watch. There is thus never a risk of over-tensioning of the mainspring. 
     In the second embodiment of the sealing device shown in  FIG. 7 , the compression key  6  has no wing  9  but rather a can be manipulated by a notched crown. In this embodiment, the tube  1  comprising the screw thread  2  comprises a central cylindrical passage over all its length and the joint  15  is disposed between the end external surface of the tube  1 , the upper portion  8  of the compression key  6  and the shaft  16  of the crown  17 . In this embodiment, the compression joint  15  is mounted without the split ring  17 . 
     In the third embodiment, shown in  FIG. 8 , the external surface of the compression key  6  forms a milled or striated cone and the crown  17  is mounted on the shaft  16  so as to be able to slide axially against the action of a spring  20  by means of a ring  21  driven into the crown  17  serving as an axial abutment. The skirt of the crown  17  has an internal surface that forms a cone corresponding to the external cone of the compression key. Thus, when the user pushes on the crown  17  against the action of the spring  20 , he can drive in rotation the compression key  6  with the help of the crown  17  by coupling of the two cones. 
     In the modifications illustrated in  FIGS. 9 and 10 , the drive of the compression key  6  by the crown  17  takes place by the wings or by six flats that couple when the crown  17  is pushed against the action of the spring  20 . 
     In these three last embodiments ( FIGS. 8-10 ) the crown  17  is axially movable against the action of a spring  20  relative to the shaft  16  and this axial movement engages and disengages a drive coupling between the crown  17  or the ring  21  which is secured to it, and the compression key  6 . The user can thus screw or unscrew the compression key by pushing on the crown  17  and driving the latter in one direction or the other. This coupling can be effected by the wings  22  and corresponding recesses  23  ( FIG. 9 ) or by six female flats  24  and six male flats  25  (FIG.  10 ).