Water-tight fitting of a glass in a watch case
BACKGROUND OF THE INVENTION 
     The invention relates to watch cases of the type including a middle-bezel having a non-circular upper opening receiving a glass of corresponding non-circular shape and a circular lower opening receiving a circular back. 
     Numerous water-tight cases of this type are known but, in the known cases, the glass is either introduced through the circular opening for the back of the case and its dimensions cannot be greater than the dimensions of this opening, or it is fixed by means of a joint on a shoulder of a bezel, which involves problems regarding water-tightness and securing of the dial and hands as the dial is often larger than the watch movement. 
     An aim of the invention is to avoid these disadvantages and to permit the use of a dial of large dimensions. 
     Another aim is to provide a water-tight case of simple constuction enabling an easy fitting of an assembly of a movement, dial and hands. 
     SUMMARY OF THE INVENTION 
     The watch case according to the invention is characterized in that the glass has an outwardly-directed peripheral flange dimensioned to be able to pass with a slight play through the upper opening in the middle-bezel, and the middle-bezel has an inwardly-directed collar defining said upper opening, and comprises a packing seal having a part disposed under said collar and a port resting of said flange, and means applying pressure to the glass to compress the seal between said collar and flange and hold the glass in said upper opening. 
    
    
     The accompanying drawings show, by way of example, an embodiment of the invention. In the drawings: 
     FIG. 1 is a view in partial cross-section taken along line 1--1 in FIG. 4, of a watch case according to the invention, during assembly; 
     FIG. 2 is a similar view of the assembled case 
     FIG. 3 is another, generally similar view, taken during assembly but along line 3--3 in FIG. 4; and 
     FIG. 4 is bottom view of the complete, assembled case. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The watch case shown includes a middle-bezel 1 having at its upper part a non-circular opening 2, receiving a glass 3 having an inclined part 4 which terminates with an outwardly-directed peripheral flange 41. The middle-bezel 1 has at its lower part a threaded circular opening 14 screwably receiving a circular back 13 (FIG. 2). The flange 4a of the glass has a peripheral shape and dimensions which correspond, with a slight play, to those of the opening 2 of the middle-bezel 1, so that the glass 3 can be passed through the opening 2. 
     The upper opening 2 of middle-bezel 1 is defined by an integral inwardly-directed collar having a shoulder 2a at the upper end of a groove 1a milled parallel to the plane of the case. This shoulder serves as a bearing for the upper face of a part 5a of a packing seal 5 which consists of compressible material such as rubber or synthetic plastic, as shown and as will be described. The middle-bezel of course is rigid. The seal, as shown, has a flat lower face which has an outer edge adjacent to but larger than the circumference of opening 2, and has an inner edge larger than the circumference of opening 2, and has an inner edge also adjacent to but smaller than this circumference. The upper face of flange 4a fits under the lower face of the part 5a of seal 5. 
     A movement-holder ring 10 transmits to the flange 4a of the glass a pressure to upwardly press the glass flange 4a against an inner part of the seal 5, adjacent to said inner edge, for compress the seal 5 between the shoulder 2a of the middle-bezel and the flange 4a. In addition to its part 5a, which forms an outwardly-directed flange, the seal has an inner part 5b having a vertical outer face fitting against the face of opening 2, and an inclined, upwardly converging inner face 5c. The inclined part 4 of glass 3 has, extending from the upper face of flange 4a, a bevelled, upwardly converging outer face 7 complementary to and generally conforming with face 5c  of the seal. In this manner, the seal 5 is compressed outwardly against the face of opening 2 and into the groove 1a in response to the applied upward pressure, and the glass 3 is hence firmly held in the opening 2. The combined outward and upward compression or pressure is applied to the seal 5 by the glass flange and part 4, 4a, through the dial 8 and the ring 10 by screwing the back 13 into a lower, threaded opening 14 of middle-bezel 1; the back 13 being smaller than the middle-bezel, as is shown in FIGS. 2 and 4. 
     Assembling of the movement and its associated parts in the watch case is very simple: 
     1. A sub-assembly comprising a movement 9 mounted in the ring 10, a dial 8 and hands 15 is introduced into the middle-bezel 11 through the opening 2. This sub-assembly cannot fall out, as the upper part 11 of ring 10 has the same non-circular shape as the opening 2 and comes to rest on a part 10a defining the threaded circular opening 14, whereas its lower part is cylindrical and passes through the opening 14, as shown in FIG. 3; 
     2. the glass 3 is placed on the dial 8 then the seal 5 is placed in groove 1a, as shown in FIGS. 1 and 3; and finally, 
     3. the bottom 13 (FIG. 4) is screwed into the lower threaded opening 14 (FIG. 2). 
     During this screwing, the upper edge of back 13 pushes the ring 10, which, by the intermediary of dial 8, compresses the seal 5 between the shoulder 2a and the upper edge of flange 4a, as shown in FIG. 2. 
     To dismantle the case, the back 13 is unscrewed and removed so that the movement sub-assembly reassumes the position shown in FIG. 1. The seal 5 is then removed, which can be done without damaging it, as its material is flexible and the sub-assembly is removed by turning over the middle-bezel 1. 
     As a variation, it would be possible to provide a longer threading in the opening 14 and to secure the ring 10 by means of a threaded ring screwed in opening 14. The sealing pressure could thus be obtained, and the movement sub-assembly fixed in the case, without action by the back. This may facilitate certain operations such as regulation and securing of a winding stem.