BRIEF DESCRIPTION OF THE DRAWINGS
Other features and advantages of the present invention will appear more clearly from the following description of an example embodiment of the securing device according to the invention, this example being given purely by way of non-limiting illustration with reference to the annexed drawings, in which:
FIG. 1 is an exploded partial cross section of a watchcase of the invention;
FIG. 2 is a cross-section made at the position of the snug of the metal element of a timepiece including an intermediate element for securing the back cover in accordance with the invention;
FIG. 3A is a partial cross-section of a watchcase according to the invention onto which the back cover is screwed in abutment against the middle case of the watch case;
FIG. 3B is a partial view of the visible face of the back cover of the watch case in a non aligned position;
FIG. 4A is a partial cross-section of a watchcase according to the invention in which the back cover has been aligned in a desired position after having been screwed in abutment against the middle case of the watch case;
FIG. 4B is a similar view to that of FIG. 3A, the back cover being here in an aligned position;
FIG. 5 is a perspective view of the intermediary element;
FIG. 6 is a similar view to that of FIG. 2 showing an alternative embodiment; and
FIG. 7 is a similar view to that of FIG. 1 showing another embodiment of a watchcase according to the invention.
DETAILED DESCRIPTION OF THE ILLUSTRATIVE EMBODIMENTS
The present invention proceeds from the general inventive idea which consists in screwing a back cover not directly onto the middle part of a watchcase, but onto an intermediate element screwed respectively onto the back cover and the middle part via two screw threads having opposite pitches. Thus when the back cover is screwed in abutment against the middle part, the back cover can still be rotated with respect to the middle part of the watchcase in order to adjust its alignment for example with respect to the vertical 12 o'clock-6 o'clock axis of the watch. This is made possible owing to the displacement of the intermediary element along the screw thread of the middle part, displacement allowed via the arrangement of the two screw thread having pitches in opposite directions. As a result of these features, the present invention provides a timepiece whose middle part and back cover do not need to be machined with great precision, which allows the manufacturing costs to be reduced.
The watchcase according to the invention is shown in cross-section and in separate parts in FIG. 1. Designated as a whole by the general reference numeral 1, the watchcase includes a middle part 2 defining a housing 4 closed in a classical manner by a crystal (not shown) and a back cover 6 as well as an intermediary element 8 intended to be inserted between back cover 6 and middle part 2. Middle part 2 has a hole 10 for the passage of a stem (not shown) onto which a crown 12 is secured. Back cover 6 which in the example shown, is circular, has a screw thread portion 14 the pitch of which is oriented in a first direction while middle part 2 has screw thread portion 16 the pitch of which is oriented in a second direction opposite to that of back cover 6. Intermediary element 8 has a first screw thread portion 18 intended to cooperate with screw thread portion 14 of back cover 6 and second screw thread portion 20 intended to cooperate with screw thread portion 16 middle part 2. In the embodiment shown, intermediary element 8 has the form of a ring having a circular inner opening 22. The outer surface of ring 8 has steps and includes a cylindrical section 24 having a first diameter D1 followed by a cylindrical section 26 having a second diameter D2 smaller that said first diameter D1.
First screw thread portion 18 of ring 8 is made in the cylindrical wall of opening 22 thereof while second screw thread portion 20 is made in outer cylindrical portion 24 of large diameter of ring 8.
It will be noted that section 26 of ring 8 of smaller diameter includes at its outer surface an annular groove 28 in which an elastic ring 30 is disposed, the function of which will be described hereinafter.
In FIG. 1, one can also see that the face 32 of back cover 6 oriented towards the inside of the watchcase 1 includes an annular groove 34 one vertical wall of which includes screw thread 14 intended to cooperate with screw thread 18 of ring 8. The width of groove 34 is dimensioned to accommodate section 26 of smaller diameter of ring 8 and compress elastic ring 30 against wall 36 of groove 34 opposite screw thread 14 when ring 8 is screwed onto back cover 6. Thus, it will be understood that when elastic ring 30 is compressed against wall 36 of groove 34, the friction forces between ring 8 and back cover 6 increase and generate an increase in the friction couple between these two elements.
As an example, ring 8 can be made of steel. Elastic blocking element may be made of a natural or synthetic elastomer, or even of a thermoplastic material whose remanence set after compression is well suited to the requirements of the present invention.
Preferably, the height of portion 24 of larger diameter of ring 8 is smaller the height of portion 26 of smaller diameter of ring 8 and the depth of annular groove 34 of back cover 6 is equal or larger than the height of portion 26 of smaller diameter of ring 8.
It will be noted that an O-ring 38 is classically inserted in an annular groove 40 made in the bottom region of middle part 2 for assuring the water tightness between back cover 6 and middle part 2 and that the outer surface 42 of back cover 6 turned to the side of the wrist of the person wearing watch 26, includes notches 44 which are used for introducing the studs of a chuck key (not shown).
In FIG. 6 is shown an alternative embodiment of the watchcase according to the invention in which the elements identical to those already described hereinabove are designated by the same numeral references. This alternative embodiment differs from the watchcase described in connection with FIGS. 1 to 5 in that the means for increasing the friction couple between ring 8 and back cover 6 are formed a cylindrical sleeve 50 arranged on cylindrical portion D2 of smaller diameter of ring 8, the external diameter of sleeve 50 and the diameter defined by the inner wall 36 being adjusted to generate a friction when ring 8 is screwed onto back cover 6. The sleeve can typically be made of Asutane, marketed by the company Asulab SA, Marin, Switzerland.
In FIG. 7 is shown another alternative embodiment of the watchcase according to the invention in which the elements identical to those already described hereinabove are designated by the same numeral references. This alternative embodiment differs from the watchcase described in connection with FIGS. 1 to 5 in that screw thread portions 18 and 20 of ring 8 are both made on the outer periphery of the ring and in particular on the same diameter. It will also be noted that screw thread portion 14 of the back cover is made in the wall opposite the groove, and that the means for increasing the friction couple between ring 8 and back cover 6 are formed of a sleeve 50 arranged in groove 34 between the wall of the groove opposite screw thread portion 14 and the inner cylindrical wall of ring 8.
The method for aligning back cover 6 of watchcase 1 on middle part 2 will now be described in connection with FIGS. 2 to 5.
In a first step, ring 8 is assembled to back cover 6 by screwing one of these elements on the other in a first direction of rotation until portion 24 of larger diameter abuts against face 32 of back cover 6. O-ring is thus compressed against wall 36 of groove 34 and generates a friction couple that is higher than the friction couple between ring 8 and middle part 2 when ring 8 will be subsequently screwed onto middle part 2.
Once the assembly formed of back cover 6 and ring 8 secured to each other by screwing formed, the assembly is the screwed, by inserting the studs of a chuck key in notches 44, onto middle part 2 via screw thread 20 which has a pitch in a direction opposite to that of the screw thread 18 and which cooperates with screw thread 16 of said middle part 2. The screwing of the assembly back cover 6-ring 8 stops when back cover 6 abuts against the lower surface of middle part 2.
Once screwed on, it can be seen in FIG. 3A that back cover 6 onto which a design 46 (in this case, it is the capital Greek letter omega) has been added, is totally out of alignment with respect to the vertical 12 o'clock-6 o'clock axis of watch. The problem thus consists in correcting this design 46 so that it is properly aligned and that the aesthetic appearance of watch is thereby improved. For that purpose, once back cover 6 has been screwed in abutment against intermediary element 8, one continues screwing back cover 6 again using the chuck key. At that time, as back cover 6 abuts against middle part 2, and as ring 8 is screwed onto back cover 6 via a screw thread 18 the pitch of which has direction opposite to that of screw thread 20 via which ring 8 is screwed onto middle part 2, back cover 6 can be rotated to align it in a desired manner, thereby causing a vertical displacement of ring 8 along screw thread 16 of middle part 2 (FIG. 4A).
The problem now arises as to how to unscrew back cover 6 when this is necessary. In order to do this, one continues to use the chuck key to unscrew this assembly until the assembly back cover 6-ring 8 is totally unscrewed from middle part 2, the friction between back cover 6 and ring 8 holding the assembly together. Thereafter, using the same chuck key or any other appropriate tool, one unscrews ring 8 from back cover 6. For that purpose, ring 8 includes notches 48 for accommodating the studs of the tool (see FIG. 5). In an alternative manner, one can continue to screw back cover 6 in order to cause the displacement of ring 8 towards the inside of the middle part along screw thread portion 16 until the ring separated from back cover 6.
The method described above can be applied mutatis mutandis to the embodiments of the watchcase of the invention shown in FIG. 6 and 7.
As it will have been understood from the above, the present invention can be applied to any type of watch pieces having a back cover screwed onto the middle part and requires, to be implemented, minor changes only, which concerns essentially the shape of the middle part 2 in its lower part where the junction with the back cover 6 is made.
It goes without saying that the invention is not limited to the embodiment which has just been described and that various simple modifications and variants can be envisaged without departing from the scope of the invention. In particular, one could envisage that the ring is screwed on the back cover via a screw thread provided on the outer surface of its cylindrical portion of larger diameter and the ring is screwed on the middle part via a screw thread provided on the inner surface of its cylindrical portion of smaller diameter.
Patent Application
20080043577
