CH715971A2 - Watch case including a rotating bezel. - Google Patents

Abstract

The invention relates to a watch case (1) comprising a rotating bezel (4) and a middle part (3), the bezel (4) being rotatably mounted on the middle part (3), said bezel (4) and said middle part. (3) defining between them an annular chamber in which is included a device for creating a friction torque (11) between the bezel (4) and the middle part (3), said device (11) comprising a compression member ( 14) and a braking element (15), the compression member (14) exerting on the braking element (15) a compressive force under the effect of which said braking element (15) is pressed against the bezel ( 4).

Description

Technical area

The present invention relates to a watch case of a timepiece comprising a middle part and a bezel capable of rotating on the middle part, said case comprising a device for creating a friction torque interposed between the bezel and said build.

[0002] The invention also relates to a watch comprising such a box provided with this device.

Technological background

[0003] In the state of the art, external rotating bezels generally equip diver's watches, watches indicating universal time, and are used in numerous applications. In general, the rotating bezel is fluted at its periphery so as to be easily grasped. In addition, it must be mounted on a middle part of a watch case so as to rotate regularly without offering too much resistance but without moving inadvertently. The mounting of the rotating bezel must therefore be such as to ensure regular friction between the parts of the same series in order to allow rational manufacture not requiring alterations to each part. In addition, the fixing device must be easy to put in place and present a sufficient guarantee against tearing off in the event of an accident or untimely friction, and on removal.

[0004] It is known that a rotating bezel is conventionally mounted on the middle part by means of a corrugated metal wire or with sides engaged simultaneously in the grooves of the bezel and of the part of the middle part which carries it. When the bezel is put in place, the metal wire undergoes elastic deformations which modify its development in length. The tear-off guarantee is not always satisfactory and, moreover, the correct positioning of these known devices is often difficult.

[0005] Rotating bezels are also known which are connected to a fixed part of the box by a flat elastic ring, split radially at a point on its periphery and the outer edge of which as well as the inner edge are engaged in grooves that present the rotating bezel and the part that carries it. Such an assembly ensures the guiding of the rotating bezel with sufficient precision, but requires an additional device which blocks the two ends of the ring relative to one of the parts of the assembly.

Summary of the invention

The object of the present invention is to remedy the aforementioned problems as well as others by improving the known mounting operations of the rotating bezel on the middle part of the watch case so that they better meet the various requirements. related to the use of this bezel.

[0007] To this end, the present invention relates to a watch case comprising a rotating bezel and a middle part, the bezel being mounted so as to be able to rotate on the middle part, said bezel and said middle part defining between them an annular chamber in which is included a device for creating a friction torque between the bezel and the middle part, said device comprising a compression member and a braking element, the compression member exerting a compressive force on the braking element under the effect of which said brake element is pressed against the bezel.

[0008] Thanks to these characteristics, the device for creating a friction torque between the bezel and the middle part thus participates in ensuring throughout the life of the watch a braking by friction / friction constant, regular and robust which allows thus the bezel to rotate regularly without offering too much resistance but without moving inadvertently.

[0009] In other embodiments: <tb> <SEP> - the compression member is an o-ring type seal; <tb> <SEP> - the braking element is a polyoxymethylene ring; <tb> <SEP> - the shore hardness and / or the compression member section contributes to defining the compressive force applied to the braking element; <tb> <SEP> - the annular chamber is formed by a groove formed in an outer wall of the middle part and by a portion of an inner wall of the bezel; <tb> <SEP> - the compression member is defined to be in contact with both the groove of the annular chamber and the braking member; <tb> <SEP> - the braking element is defined to be in contact with both the portion of the annular chamber and the compression member; <tb> <SEP> - the braking element comprises a friction face provided to cooperate with a contact zone of a portion of the annular chamber, and <tb> <SEP> - the watch case comprises two grooves defined respectively in the middle part and the bezel by being arranged facing each other and provided to include a spring participating in the mounting of the bezel on the middle part.

[0010] The invention also relates to a watch comprising such a box.

Brief description of the figures

The invention will be described below in more detail with the aid of the accompanying drawings, given by way of non-limiting examples, in which: <tb> <SEP> - Figure 1 is a partial sectional view of a watch case according to the present invention; <tb> <SEP> - figure 2 is a view on a larger scale of part A of this box illustrated in figure 1, according to the present invention; <tb> <SEP> - Figure 3 is a partial sectional view of a variant of the compliant watch case, and <tb> <SEP> FIG. 4 is a view on a larger scale of part B of this variant of the box illustrated in FIG. 3, according to the present invention.

Detailed description of the invention

The present invention will be described in connection with a watch case 1, in particular a waterproof case. Such a watch case 1 is preferably included in a wristwatch. It goes without saying that this example is given purely by way of illustration and that the present invention can be applied to any type of timepiece such as a pocket watch.

In Figures 1, 2 and 3, this watch 100 comprises a box 1 designated as a whole by the general reference numeral 1, comprising a base 2 and an assembly formed by a caseband 3 and a bezel 4 rotatably mounted on the middle part 3. This middle part and this bezel can be made, for example, of steel, of precious metal (gold, silver, platinum), of an alloy based on precious metals or of ceramic, etc.

Such a middle part 3 comprises an annular groove 16 defined on its outer wall and which is positioned in this box 1 facing an inner face of the bottom 2, said groove 16 comprising a seal 17. The middle part 3 and this back 2 delimit a volume in which the various parts of the watch 100 are housed. A glass / crystal 5 is fixed to the middle part 4 with the interposition of a seal 18 between the glass 5 and said bezel 4.

The middle part 3 on which the bezel 4 is mounted movable in rotation, has two annular grooves 6 and 7 for mounting the bezel 4 and defined in the outer wall of this middle part 3. The bezel 4 is mounted on the middle part 3 by means of a spring 8, for example a multipan or polygonal wire spring engaging in the groove 6 of the middle part 3 as well as in a groove 9 of the bezel 4. The grooves referenced 6 and 9 are arranged opposite one of the other and are formed respectively in the cylindrical outer wall of the middle part 3 and a cylindrical inner wall of the bezel 4. Thus by this spring 8, the bezel 4 is pressed downwards against a shoulder 10 of the caseband 3.

The groove 7 of the middle part 3 comprises part of a device for creating a friction torque 11 participating in the mounting of the bezel 4 on this middle part 3. More precisely, this groove 7 is included in an annular chamber 12 of the watch case 1, which chamber 12, visible in FIG. 2, being defined between the bezel 4 and the middle part 3 in particular between the outer wall of the middle part 3 and the inner wall of the bezel 4.

This annular chamber 12 in which the device for creating a friction torque 11 is arranged, is therefore formed by the groove 7 formed in the outer wall of the middle part 3 and by a portion 13 of the inner wall of the bezel 4, this groove 7 and this portion 13 being arranged facing one another. It will be noted that this portion 13 comprises a contact zone 19 provided to cooperate with a friction face of a braking element 15 of the device 11.

Note with reference to Figure 3, that in a variant of the watch case 1, the device for creating a friction torque 11 comprises is therefore formed by the groove 7 and an annular groove 20 both formed in the outer wall of the middle part 3, and by a portion 13 of the inner wall of the bezel 4. In this configuration, the braking element 15 is arranged in the groove referenced 20 so that its friction face cooperates with the contact zone 19 of the device 11. It will be noted that such a configuration offers the advantage of allowing disassembly of the case 1, in particular disassembly of the bezel with the middle part, during which the braking element 15 and the compression member 14 are held in position in the middle part 3.

In this configuration, the device for creating a friction torque 11 between the bezel 4 and the middle part 3, comprises a compression member 14 and this braking member 15. This compression member 14 is arranged in the groove 7 of the annular chamber 12 being both in contact with the bottom of the groove 7 or even the walls of the latter, and the braking element 15. As regards the braking element 15, it is defined for be in contact with both the contact zone 19 of the portion 13 of the annular chamber 12 and the compression member 14. In this context, this compression member 14 is arranged in the annular chamber 12 so as to exert on the braking element 15 a compressive force under the effect of which said braking element 15 is pressed against the bezel 4. In other words, it is understood that in this configuration, a braking by friction of the rotation of the bezel 4 is carried out at means of the compression member 14 arranged in the groove 7 which makes a compressive contact with the braking element 15 itself in frictional contact with the contact zone 19 of the portion 13 of the bezel 4. Such a contact zone 19 of the portion 13 is defined to cooperate with the braking element 15 of the device 11.

It will be noted that in this device 11, the compression member 14 and the braking element 15 necessarily have at least one different characteristics relating, for example, to the material constituting them, to their elasticity, to their tensile strength, their resistance to compression breakage, their resistance to wear, their resistance to chemical agents, their dimensional stability, their resistance to creep, their coefficient of friction, their resistance to abrasion, etc ...

In this context, the compression member 14 is an O-ring such as an o-ring type seal of profile / circular section. The o-ring seal is kept compressed in the groove 7 of the annular chamber 12, this groove 7 can then have a profile similar to that of this seal, for example a groove 7 of circular profile or more conventionally and as illustrated on the figures, in rectangular profile. In a particular embodiment, the material constituting this o-ring seal comprises, for example, rubber, silicone, nitrile or even any other elastomer of the brands Isoswiss ™ and Isochron ™. It will be noted that the compression member has very good abrasion resistance.

In this device 11, the braking element 15 is in turn a ring. This braking element 15 can be made of a polymer, in particular of polyoxymethylene, better known by the acronym “POM” or also under the name “Acetal”. This braking element 15 is for example a single piece but it can also be formed of several pieces cooperating together. This braking element 15 comprises the friction face provided to cooperate with the contact zone 19 of the portion 13 of the inner wall of the bezel 4, this face and this portion 13 both have complementary profiles. In other words, the contact zone 19 almost perfectly matches the shape of the friction face of the braking element 15. This braking element 15 comprises a section of shape essentially similar to that of a quadrilateral.

[0023] Such a braking element preferably has: <tb> <SEP> - an elasticity coefficient of 2,500 to 3,500 GPa, greater than that of the compression member 14 which is between 0.001 and 0.1 GPa, and which preferably corresponds to a hardness of 60 to 80 shore and a maximum compression of 20%; <tb> <SEP> - a low coefficient of friction of 0.25 to 0.60 (especially on steel), invariable with the conditions: dry, wet, greased; <tb> <SEP> - good wear resistance of 0.75u / km and defined by practical application which has shown good results especially when the braking element is in POM and the bezel is in steel;

[0024] It will generally be noted that the braking element has good resistance to fatigue, to chemical agents, to creep and to temperatures, in particular when it is made of POM.

As we have seen, the compression member 14 exerts a compressive force also called the compression ratio on the braking element 15. This compression ratio of the compression member 14 can be adapted freely in adjusting the Shore hardness or the section of this compression member 14. This compression ratio of the compression member 14 also participates in determining the torque of the bezel 4 or the intensity of the friction torque between the bezel 4 and caseband 3.

Of course, the present invention is not limited to the example illustrated but is susceptible of various variants and modifications which will appear to those skilled in the art.

Claims (10)

1. Watch case (1) comprising a rotating bezel (4) and a middle part (3), the bezel (4) being rotatably mounted on the middle part (3), said bezel (4) and said middle part (3) defining between them an annular chamber (12) in which is included a device for creating a friction torque (11) between the bezel (4) and the middle part (3), said device (11) comprising a compression member ( 14) and a braking element (15), the compression member (14) exerting on the braking element (15) a compressive force under the effect of which said braking element (15) is pressed against the bezel ( 4). 2. Box (1) according to the preceding claim, characterized in that the compression member (14) is an o-ring type seal. 3. Box (1) according to any one of the preceding claims, characterized in that the braking element (15) is a polyoxymethylene ring. 4. Box (1) according to any one of the preceding claims, characterized in that the shore hardness and / or the compression member section (14) helps to define the compressive force applied to the braking element (15). . 5. Box (1) according to any one of the preceding claims, characterized in that the annular chamber (12) is formed by a groove (7) formed in an outer wall of the middle part (3) and by a portion (13) ) an inner wall of the bezel (4). 6. Box (1) according to any one of the preceding claims, characterized in that the compression member (14) is defined to be in contact both with the groove (7) of the annular chamber (12) and the braking element (15). 7. Box (1) according to any one of the preceding claims, characterized in that the braking element (15) is defined to be in contact with both the portion of the annular chamber (12) and the member. compression (14). 8. Box (1) according to any one of the preceding claims, characterized in that the braking element (15) comprises a friction face provided to cooperate with a contact zone (19) of a portion (13) of the annular chamber (12). 9. Box (1) according to any one of the preceding claims, characterized in that it comprises two grooves (6, 9) defined respectively in the middle part (3) and the bezel (4) being arranged opposite the one from the other and designed to include a spring (8) participating in the mounting of the bezel (4) on the middle part (3). 10. Watch comprising a box (1) according to any one of the preceding claims.