Patent ID: 12253829

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to a watch case10a portion of which is shown in the sectional view according to a radial plane of said watch case10ofFIG.1.

The watch case10includes a middle20of generally circular shape including an axial opening21receiving a crystal (not shown) at one of its ends referred to as “upper end” opposite a back30driven at another end of said middle20, referred to as “lower end”. The crystal, the back30and the middle20define a volume inside of which is arranged a horological movement, in a manner known by the person skilled in the art.

As the horological movement and the other horological components used in a watch case10are known by the person skilled in the art and do not form part of the present invention, they are not shown in the figures, or described hereafter.

The back30has a generally circular shape and includes a body31from which radially extends a lip32forming a peripheral shoulder in relation to said body31. More specifically, as shown in the sectional view ofFIG.1, the shoulder is formed by an axial annular shoulder310of the body31and by a radial annular shoulder320of the lip32.

Said axial310and radial annular shoulders320are provided to constitute bearing surfaces as described in more detail hereafter.

The axial and radial directions are defined in the present text relative to the watch case10, and in particular relative to the opening21of the middle20. In a manner known in the field of horology, the axial direction extends from one another of the upper and lower ends of the middle20and the radial direction extends perpendicularly to said axial direction.

At its lower end, the middle20has an axial annular shoulder200extending opposite the axial annular shoulder310of the back30. This axial annular shoulder200is connected to a radial annular shoulder201resting against the radial annular shoulder320of the lip32. The radial annular shoulder201of the middle20forms an end surface of said middle20in the preferred example of embodiment of the invention shown in the figures.

An annular joint40is advantageously interposed between the axial annular shoulders200and310respectively of the middle20and of the back30, and is compressed by one and the other of said axial annular shoulders200and310, as shown inFIG.1. This compression of the joint40makes it possible to give a water-resistance and airtightness to the watch case according to a desired level and generates a torque making it possible to fasten the back30on the middle20.

Advantageously, the axial annular shoulders200and310of the middle20and of the back30are of complementary shapes, and do not have a revolution shape. On the contrary, although it has a substantially circular shape, as shown inFIGS.2and3, their respective peripheral profile includes a first circular-arc-shaped portion having a first radius R1, R2 and a second circular-arc-shaped portion connected to the first portion and having a second radius r1, r2 smaller than the first radius R1, R2. The first portions of the middle20and of the back30are intended to rest facing one another, in the same way that the second portions of the middle20and of the back30are intended to rest facing one another.

The first and second radii R1, R2 and r1, r2 are shown inFIGS.2and3by sagittas.

The term “peripheral profile” defines in the present text the projection of the axial annular shoulders200and310respectively of the middle20and of the back30on a plane P perpendicular to the axial direction and parallel to the radial direction. In other words, the plane P is parallel to the radial annular shoulders201and320of the middle20and of the lip32, such as shown inFIGS.1and2.

The term “complementary” means that the shapes of the axial annular shoulders200and310are identical, only the dimensions of said axial annular shoulders varying in relation to one another.

These conformations of the back30and of the middle20, visible respectively inFIGS.2and3, make it possible to guarantee the performance of the water-resistance and airtightness of the watch case10by preserving the peripheral profile of the axial annular shoulders200and310of any angle, broken line or edge, etc., by the continuity of the curved surfaces, while playing a role of polarizer in the orientation of the back30opposite the middle20during their assembly with one another.

Indeed, to drive the back30into the middle20, it is then only possible to orient the back30according to a position wherein the shapes of the axial annular shoulders200and310are aligned with one another, that is to say a position wherein the first portions are arranged facing one another and the second portions are arranged facing one another.

Advantageously, to guarantee a high level of water-resistance and airtightness the shape defined by the peripheral profile of the axial annular shoulders200and310of the middle20and of the back30is convex, inasmuch as said axial annular shoulders200and310are located respectively entirely on the same side of a tangent line applied in any point of their peripheral profile. The term “convex” is used here in its definition specific to the field of geometry.

Preferably, in a preferred example of embodiment of the invention, the values of the second radii r1, r2 of the second portions of the axial annular shoulders200and310of the middle20and of the back30are respectively greater than half the values of the first radii R1, R2 of the first portions of the middle20and of the back30.

This feature contributes to the continuity of the curved surfaces and therefore to preventing that the shape of the peripheral profile of the axial annular shoulders200and310does not include edge or broken line angles.

In particular, the difference between the values of the first and of the second radii R1 and r1 of the axial annular shoulder200of the middle20, as well as the difference between the values of the first and of the second radii R2 and r2 of the axial annular shoulder310of the back30, is in the order of a few millimetres or tenths of millimetres.

As shown inFIGS.2and3, the shape of the axial annular shoulders200and310of the middle20and of the back30comprises a plurality of first and second circular-arc-shaped portions alternately distributed, one after another. In other words, two successive first circular-arc-shaped portions are connected to one another by a second circular-arc-shaped portion and two successive second circular-arc-shaped portions are connected to one another by a first circular-arc-shaped portion.

In the preferred example of embodiment of the invention, the axial annular shoulders200,310of the middle20and of the back30are configured so that the sagittas of the first and second circular-arc-shaped portions are separated from one another by an angle of 60 degrees. The notion ofsagittaof a circular arc is known by the person skilled in the art. This angle easily acts as an effective polarizer making it possible to orient a back in a middle. An orientation defect would be rapidly perceptible and correctable for the operator.

In other terms, the axial annular shoulders200and310of the middle20and of the back30include three first portions and three second circular-arc-shaped portions alternately distributed one after another.

Moreover, thesagittaof the circular-arc-shaped portions define segments of intersecting lines in a point materializing the centre of the opening21.

Preferably, the joint40has a peripheral profile complementary to those of the axial annular shoulder310of the lip32and of the axial annular shoulder200of the middle20.

InFIG.1, the joint40has been shown with a rectangular-shaped cross-section. In other examples of embodiment of the invention, it may include a circular or other shaped cross-section.

Advantageously, the radial annular shoulder320of the back30may include an annular added thickness321to receive the bearing joint40, as shown inFIGS.1and3. Thus, the radial annular shoulder201of the middle20rests against an end portion of the radial annular shoulder320of the back30.

The back30and the middle20may be made of any suitable material, for example metal, such as steel or precious metal, ceramic, etc.

The joint40may also be made of any suitable material, such as polymer, having a Shore D hardness of 75±10.

More generally, it should be noted that the implementations and embodiments considered above have been described by way of non-limiting examples, and that other variants are consequently possible.

For example, it is possible that the peripheral profile of the axial annular shoulders200and310of the middle20and of the back30has more than two circular-arc-shaped portions the radii of which are different and/or that it includes more than three first portions and more than three second circular-arc-shaped portions alternately distributed one after another.