FR2786574A1 - WATERPROOFING GASKET AND WATERPROOFING DEVICE FOR A WATCHMAKING PART - Google Patents

Abstract

The invention concerns a sealing joint for timepiece component, having the shape of an annular band (10) defining an axis of symmetry (12) whereof the inner part (14) comprises at least an annular projection (22) for positioning and the outer part (16) at least two annular protuberances (24, 25, 26) each substantially formed by a half-torus extending radially outwards. The invention is characterised in that it further comprises an annular lip (20, 21) formed by a half-torus extending axially outwards and arranged at one of the ends (18, 19) of said band. The invention is applicable to sealed control devices for timepiece components.

Description

SEAL AND WATERPROOFING DEVICE FOR A
WATCHMAKING PIECE
The present invention relates to sealed control devices for timepieces and more particularly to a seal intended to equip such a part. A timepiece fitted with a device of this type is described in European patent 0'429'974. It includes a housing comprising a crown, a tube and a seal.

The joint is in the form of an annular bandage, the internal part of which comprises an annular positioning projection and the external part two annular bosses extending radially outwards.

Such a seal is mounted in a groove that comprises the tube. 11 is intended to cooperate with a time-setting crown comprising a rod capable of occupying at least two positions, and a head in the form of a cap with a bottom and a skirt, the latter having a cylindrical inner surface.

The whole is arranged so that the interior surface of the skirt remains permanently in contact with the joint in one as in the other of its positions.

Such a solution makes it possible to produce waterproof watches in which at least one of the bosses of the seal is well protected, thus preventing abrasive dust from damaging it.

When the watch has to withstand high pressures, as in the case of so-called diving watches, boxes are used whose crown is screwed. A solution of this type is, for example, described in patent CH 520,963. It relates to a watch in which the seal is obtained by means of two seals, one of which, of annular shape with rectangular section, is engaged in a groove made in the external cylindrical part of the tube and cooperates with a cylindrical part of the crown skirt. The second seal has the shape of a washer, pressing against a collar that the tube comprises when it engages in the housing, and compressed by the end of the crown when it is screwed.

Such a solution ensures resistance to pressures exceeding 100 atmospheres, thanks to the fact that one of the seals is pressurized when the rod is screwed. This is particularly valid as long as the seals are new. Unfortunately, as soon as dust slips on one or the other of them, it is damaged and the tightness can no longer be guaranteed. However, as the second seal is located between the tube and the outer end of the crown, there is a great risk of dirt taking place there and thus destroying it or, at least, deforming it and rendering the expected performance illusory.

This defect is particularly serious for diving watches, which participate in the management of oxygen reserves and give the indications relating to the diver's ascent procedure. They can no longer count time correctly when water has entered the case.

The main object of the present invention is to provide a seal of simple design, usable both with watches with a screw crown and classic waterproof watches and guaranteeing optimum sealing. To this end, the seal according to the invention has the form of an annular bandage defining an axis of symmetry and comprising an internal part, an external part and two ends, the internal part of which comprises at least one annular projection of positioning and the external part at least two annular bosses substantially formed each of a half-torus extending radially outwards. It is characterized in that it further comprises an annular book formed by a half-torus extending axially outwards and disposed at one end of the tire.

The installation of a seal is a delicate operation. It is particularly so when the joint is not symmetrical, the latter then being able to be badly oriented. This is why, advantageously, the seal according to the invention comprises an annular book extending axially at each of its ends and has a plane of symmetry perpendicular to the axis of the rod.

In the case of diving watches, it is desirable for the seal to be able to be strongly compressed axially, which requires a good bearing surface.

This is why the seal comprises a single annular lip, disposed at one of the axial ends of the tire, the positioning projection being disposed in the vicinity of the lip.

To ensure optimum sealing, it is necessary that the pressure of the seal against the skirt is applied regularly and strongly. To this end, the pound and the boss which is adjacent to it are advantageously connected to each other by a conical surface. In this way, when the crown is screwed in, it compresses not only the pound, but also the neighboring boss. The effect is particularly important when the surface forms an angle between 30 and 60 with the axis of symmetry.

In watches with a screwed crown, the amplitude of the displacement of the crown is important. In order to ensure the best possible seal, whatever the position of the rod, the seal is characterized in that it has three bosses. In this way at least one, or even two bosses are permanently in contact with the internal surface of the skirt, which is moreover regularly cleaned by the third boss, when the rod is pulled.

The present invention also relates to a control device for a timepiece, arranged so as to take the best advantage of the seal as defined above.

11 relates more particularly to a sealed control device for a timepiece housed in a case and comprising:
a tube projecting from the housing,
a rod engaged in the tube and connected to the timepiece,
a crown secured to the outer end of the rod, and
a seal inserted between the tube and the crown and formed
an annular bandage as defined above.

The timepiece is arranged so that the crown can occupy at least three axial positions, one in which it is screwed, called the rest, the second, intermediate, where it is unscrewed, and the third, pulled , in which its rotation corrects the display of the timepiece.

The device according to the invention is characterized in that:
the tube is provided with an annular groove, made in its face
outside, in which the positioning projection is engaged and
arranged so that the lip protrudes axially from the end
out of the tube,
the crown and the tube have one thread, the other one
thread, intended to cooperate with each other so that the
crown can be screwed onto the tube,
the crown comprises a substantially cylindrical central part,
integral with the rod, and a cap having a bottom and a skirt
lateral, the bottom connecting the central part to the skirt, which define
together an annular housing in which the tube and the seal are
arranged, the internal wall of the skirt having a surface
cylindrical which extends over a height greater than the distance that
travels the crown from first to third position, and
the bottom is arranged so as to compress the joint by pressing
the pound when the crown occupies its rest position.

Other advantages and characteristics of the invention will emerge from the description which follows, given with reference to the appended drawing, in which: FIGS. 1a and 1b show two embodiments of seals according to
the invention, and FIGS. 2a to 2c represent a control device according to
the invention, provided with a seal according to the embodiment shown in the
Figure 1a, in different positions of the control rod.

The seal shown in FIG. 1a is in the form of a bandage 10, of annular shape, defining an axis of symmetry 12 and comprising an internal part 14, an external part 16, and two ends 18 and 19 respectively formed of annular books 20 and 21. The internal part 14 has, in its middle, an annular projection 22 for positioning, of rectangular section. Alternatively, not shown in the drawing, it would be possible to replace it with two projections, one 6 at each end.

The external part 16 comprises three annular bosses 24 to 26, each substantially defined by a half-torus extending radially outwards and the diameter D of the cylinder in which they are inscribed is the same for the three bosses.

The annular books 20 and 21, substantially defined by a half-torus extending axially outward, are respectively connected to the bosses 24 and 26 by a conical surface 28, forming an angle approximately equal to 45 degrees with the axis 12 It is advantageously between 30 and 60 degrees. The bosses 24 and 25 on the one hand, 25 and 26 on the other hand, are separated by grooves 29.

As can be seen in this figure, the seal has an axial symmetry, but also a symmetry about a plane 30 perpendicular to the axis 12 and passing through the middle of the seal.

The seal shown in FIG. 1b is also formed by an annular bandage 10 defining an axis of symmetry 12, with an internal part 14, an external part 16 and two ends 18 and 19. The internal part carries a projection 22, of rectangular section, in the vicinity of the end 18. The external part 16 also includes three bosses 24 to 26 and two grooves 29 interposed between the bosses. The end 18 is formed of a book 20, defined by a half-torus and extending axially outwards.

 The end 19 comprises, on the other hand, a bearing surface 32, making it possible to prevent axial displacement of the seal and to position it with precision.

This joint does not have a plane of symmetry. It is thus possible to play on a larger number of parameters to define the physical characteristics of the joint. It is thus possible to have more or less flexibility of the bandage in the area adjacent to the book 20.

In a variant not shown, it is also possible to provide the projection on the side opposite the lip. In all cases, we will seek to offset the projection so that the asymmetry is clearly visible and prevents mounting in the wrong direction.

The device shown in Figures 2a to 2c comprises a housing 50 provided with a tube 52 projecting from the housing and driving into the latter, a crown 54, pivoting in the tube, a seal formed by a bandage 10, interposed between the tube 52 and the crown 54, and a rod 56, integral with the crown 54.

In order to show the deformations of the bandage 10 when it is mounted in the timepiece, it is shown at its nominal dimensions, so that there is an overlap with the tube 52 and the crown 54, which is not of course not the case in reality.

The crown 54 includes a central part 60, substantially cylindrical, and a cap 62 comprising a bottom 64 and a side skirt 66.

The central part 60, the skirt 66 and the bottom 64 which connects them, are concentric and define an annular housing 68 in which the tube 52 and the bandage 10 are arranged when the crown is screwed, as shown in FIG. 2a.

The central part 60 of the crown 54 has, in the vicinity of the bottom 64, a thread 70. The tube 52 is provided with a thread 72 in its outer end, intended to cooperate with the thread 70 in order to be able to screw the crown onto the tube .

The side skirt 66 comprises an internal wall 66a, of cylindrical shape whose diameter is equal to T (fig 2c) and whose free end is extended by a chamfer 66b.

The tube 52 comprises an annular groove 74, formed in its outer wall and in which is engaged the projection 22 of the tire 10. In this way, the latter is perfectly positioned. It is arranged so that the pound 20 protrudes from the outer end of the tube 52.

The tube 52 further comprises a collar 76 whose outside diameter is slightly less than the diameter T, so that the crown 54 can cover it when it is screwed, and which makes it possible to position the tube 52 relative to the housing 50 .

It will also be noted that the central part 60 of the crown 54 is formed of two parts 60a and 60b, coaxial and of a coil spring 60c. This structure, which is not an integral part of the invention and which is well known to those skilled in the art, allows the crown 54 to be freely rotated when it is screwed or unscrewed, without however driving the rod. 56.

The crown 54 can occupy three axial positions, one shown in Figure 2a, in which it is screwed, called rest, the second shown in Figure 2b, intermediate, where it is unscrewed, and the third shown in Figure 2c, drawn, in which its rotation makes it possible to correct the display of the timepiece.

As can be seen more particularly in FIG. 2c, the internal wall 66a of the skirt 66, of diameter T extends over a height H greater than the distance L traversed by the crown 54 from the first to the third position .

The diameter T is less than the diameter D, the difference defining the compression to which the seal is subjected.

Figure 2a shows that the thread 70 of the central part is engaged in the thread 72 of the tube 52 when the crown 54 occupies its first position.

The skirt 66 completely covers the bandage 10, and the collar 76 over almost its entire height. Its internal wall 66a compresses the bandage 10 and more particularly the three bosses 24 to 26. The book 20 is compressed by the bottom 64, while the book 21 is in contact with the collar 76. Because of the conical shape of the surface 28 connecting the book 20 and the boss 26, the compression force applied by the bottom 64 on the book 20 is transmitted to the boss 24, which reinforces the pressure at this level and consequently the seal.

In the second position, shown in FIG. 2b, the thread 70 and the internal thread 72 are no longer engaged with each other. The skirt 66 no longer covers the collar 76 and only part of the bandage 10. As the crown is offset axially outwards, it reveals the boss 24.

In this position, sealing is ensured by the bosses 25 and 26.

In the third position, shown in FIG. 2c, the skirt 66 is in contact with the boss 26 only and compresses it. The stem occupies this position when setting the time. This is done, of course, out of the water. However, it can be performed when there is still a drop of liquid in the vicinity of the crown, which could penetrate inside the case if no action was taken. The boss 26 eliminates this risk. The tightness is all the better guaranteed when the cylindrical wall 66a is cleaned by the bosses 24 and 25 before its end part comes into contact with the boss 26.

It will be noted that the seal according to the invention can be used in all types of waterproof watches, with or without a screw-down crown. lu can indeed fulfill all the functions of the seal described in European patent 0'429'974, in addition to the additional compression which the screwing of the crown allows. In this way, it is possible to simplify the after-sales service, by reducing the number of components required, while taking advantage of the advantage already offered by seals as defined in the patent mentioned above, namely the possibility to change them while keeping the same crown.
Finally, it will be noted that by making the seals in a highly colored material, the user will be able to see at a glance that the crown is not screwed, the seal then being visible.

Claims (7)

CLAIMS 1. Seal for a timepiece, having the shape of an annular bandage (10), defining an axis of symmetry (12) and comprising an internal part (14), an external part (16) and two ends (18, 19), the internal part (14) of which comprises at least one annular projection (22) for positioning and the external part (16) of at least two annular bosses (24, 25, 26) each substantially formed of a half-torus extending radially outwards, characterized in that it further comprises an annular book (20, 21) formed by a half-torus extending axially towards the outside and arranged at one ends (18, 19) of said bandage. 2. A seal according to claim 1, characterized in that it comprises an annular book (20, 21) extending axially at each of its ends (18, 19) and in that it has a plane of symmetry (30) perpendicular to said axis (12). 3. A seal according to claim 1, characterized in that it comprises a single annular book (20), disposed at one of the axial ends (18) of said bandage (10) and in that the positioning projection (22) is arranged in the vicinity of said book. 4. Seal according to one of claims 1 to 3, characterized in that said book (20) and the boss which is adjacent to it (26) are connected to each other by a conical surface. (28). 5. A seal according to claim 4, characterized in that said surface (28) forms with said axis (12) an angle between 30 and 60. 6. A seal according to any one of the preceding claims, characterized in that it comprises three bosses (24, 25, 26). 7. Waterproof control device for a timepiece housed in a housing (50) which comprises:   a tube (52) projecting from the housing (50),   a rod (60) engaged in the tube and connected to the timepiece,   a crown (54) secured to the outer end of the rod,   a seal (10) according to any one of claims  previous, interposed between the tube and the crown, said timepiece being arranged so that the crown (54) can occupy at least three axial positions, one in which it is screwed onto the tube, called the rest , the second, intermediate, where it is unscrewed, and the third, pulled, in which its rotation makes it possible to correct the display of the timepiece, characterized in that:  the tube (52) is provided with an annular groove (74) formed in its  outer face in which said positioning projection (22) is  engaged and arranged so that said book (20) exceeds  axially from the end of the tube, towards the outside,  the crown (54) and the tube (52) have one a thread (72),  The other a thread (70), intended together to cooperate with one  the other so that the crown (54) can be screwed onto the  tube (52),  the crown (54) comprises a central part (60) substantially  cylindrical, integral with said rod (56), and a cap (62) comprising  a bottom (64) and a side skirt (66), the bottom connecting the central part  to the skirt, which together define an annular housing (68) in  which the tube (52) and the seal (10) are arranged, the internal wall  (66a) of the skirt (66) having a cylindrical surface which extends  over a height (H) greater than the distance (L) that the  crown (54) from the first to the third position, and the bottom (64) is arranged so as to compress the seal (10) in  pressing said book (20) when the crown (54) occupies its  rest position.