DEVICE FOR ATTACHING A BASE TO A CLOCK CASE FRAME

Description

Scope of the invention

[0001] The invention relates to a device for attaching a case back to a watch case.

[0002] The invention also relates to a timepiece, in particular a watch, comprising such a device. Background of the invention

[0003] The casing of watches and similar devices is subject to numerous constraints, particularly in terms of water resistance, robustness, appearance, and must be carried out in such a way as to prevent any unintentional disassembly which would inevitably result in after-sales intervention for replacement of seals, cleaning, lubrication, or even repair.

[0004] Some casing or control components still need to be angularly indexed relative to each other for marking original, rest, or actuation reference positions, or to facilitate reading indications or graduations, or to ensure the continuity of curved surfaces and / or decorative elements. This angular indexing is often difficult to achieve correctly, requiring proper tightening of the components and perfect sealing of the joints.

[0005] It is known to use an elastic closure element, independent of the components to be assembled, as in document CH 423 637 or patent CH 447 046. The main drawback of the elastic elements proposed in these documents lies in their bulk. It is also known from document CH 512 769 to use pads made of compressible materials surrounded by ring segments that cooperate with milling operations at the corners of a square or rectangular housing. Such a device is only usable on housings of a specific shape, and the elasticity provided by a compressible material such as an elastomer is subject to significant changes during the material's aging. Document JP S54 160175 U presents an elastic closure element with a particular geometry. Summary of the invention

[0006] The invention aims to achieve a watertight and secure assembly of cladding components with easy-to-adjust angular indexing.

[0007] For this purpose, the invention relates to a device for fixing a base onto a case according to claim 1.

[0008] The invention also relates to a timepiece comprising such a fastening device. Brief description of the drawings

[0009] Other features and advantages of the invention will become more apparent upon reading the following description of a particular embodiment of the invention, given by way of simple illustrative and non-limiting example, and the accompanying figures, among which: THE Figures 1a and 1b are exploded perspective views of a fastening device according to a first embodiment close to the invention; figures 2a and 2bare respectively bottom and top views of a base and a ring of a fastening device according to a first embodiment close to the invention; the figure 3 is a cross-sectional view of a fastening device according to a first embodiment close to the invention; the figure 4 is a perspective view of a ring of a fastening device according to a second embodiment of the invention; the figure 5 is a cross-sectional view of a fastening device according to a second embodiment according to the invention. Detailed description of preferred embodiments

[0010] The invention aims to achieve a watertight and secure assembly of cladding components with easy-to-adjust angular indexing, and in a guaranteed position, with a minimum number of components, and reduced manufacturing costs.

[0011] THE figures 1 to 5illustrate the non-limiting example of the mounting and angular indexing of a case back in relation to a watch case.

[0012] The invention relates to a device 100 for attaching a case back 2 to a case 1 of a watch, the case back 2 comprising a cover 20 arranged to form a bearing surface with the case 1 and a body 21 arranged to rest within the case, said device comprising a ring 4 disposed between the case back 2 and the case 1, said ring 4 being arranged to ensure the sealing and indexing of the case back. The ring 4 comprises an upper portion 40 ensuring the sealing and a middle portion 41 comprising positioning means 3 for ensuring the indexing of the case back 2 relative to the case 1.

[0013] As can be seen in the figure 1b , the case 1 has a shoulder 10 on which rests the upper part 40 of the ring 4, the ring 4 being flush with the case once in place.

[0014] Advantageously, the positioning means 3 include at least one lug 43 formed on the middle part 41 of the ring 4 and arranged to rest in a housing 11 of the case 1, the lug 43 being formed on the outer wall and extending over all or part of the height of the middle part 41 of the ring 4. Thus, the ring 4 cannot be moved in rotation when a torque is applied to the bottom for example.

[0015] The ring 4 also includes a lug 46 arranged to cooperate with a machined recess 22 in the case back 2. This arrangement allows for the correct positioning, or indexing, of the case back 2 relative to the case middle 1, which is particularly useful when the case back 2 has a decoration that must be perfectly aligned with the 12 o'clock-6 o'clock axis of the watch.

[0016] According to an embodiment of the invention illustrated in Figures 4 and 5, the ring 4 has a lower part 42, the lower part 42 having retaining means arranged to cooperate with the bottom 2, the retaining means being in the form of a protruding clip 420 arranged to fit into a groove or a housing formed in the body 21 of the bottom 2.

[0017] With this in mind, ring 4 is made of a polymer material such as Asutane® or Hytrel®. Of course, any other material that can be elastically deformed and is sufficiently strong can be used to make ring 4. The external ribs 44 and internal ribs 45 thus provide good resistance to dislodgement once the case back 2 is mounted, pressed into place, or pressed onto the case 1.

[0018] According to a preferred embodiment of the invention, the ring 4 comprises at least two internal ribs 45 and at least two external ribs 44, the ribs being spaced angularly from each other from 60° to 90°. The internal ribs 45 and the external ribs 44 are provided to be offset from each other, i.e., an external rib will not be positioned opposite an internal rib, and thus provide better support.

[0019] The case back 2 and the ring 4 are dimensioned so that, when forced into the case 1, the case back 2 radially presses the ring 4 against the case 2, thereby compressing the elastic element 4 between the case wall and the case back. The ring 4 has ribs extending along all or part of its height which, in response to the compressive force, deform to ensure a secure fit. A compression ratio of approximately 20% for the ring 4 is preferred to provide this secure fit. This ratio increases the friction between the case back 2 and the ring 4, and between the ring 4 and the case 1, thus determining the torques involved in fitting the case back 2 onto the watch.

[0020] There figure 3This illustrates a cross-sectional view of the case back 2 and the ring 4 assembled onto the case body 1, with the ring 4 compressed between the inner lateral face of the case body 1 and the case back 2. The press-fit of the case back into the case keeps the ring 4 deformed, and more specifically the external grooves. This deformation is obviously within the elastic deformation limit of the ring material.

[0021] The invention also relates to a timepiece or watch 1000 comprising such a fastening device 100.

[0022] In summary, the invention provides a fastening device with a compact design, ensures the watch remains watertight, and protects against accidental disassembly.

[0023] The invention also makes it possible to ensure the perfect orientation of a component held locked in its service position.

Claims

1. A fastening device (100) comprising a back (2) and a middle (1) of a watch, the back (2) comprising a cover (20) designed to form a bearing surface with the middle (1) and a body (21) designed to rest in the middle (1), said device (100) comprising a ring (4) arranged between the back (2) and the middle (1), said ring (4) being designed to ensure the water resistance and the angular indexing of the back (2), in which the ring (4) comprises an upper part (40) ensuring the water resistance and a median part (41) comprising positioning means (3) to ensure a precise and angularly indexed placement of the back (2) in relation to the middle, the ring (4) having a lower part (42), said lower part (42) having retaining means designed to engage with the back (2), characterised in that said retaining means are in the form of at least one clip (420) designed to engage with a groove formed in the body of the back (2).

2. The device for fastening (100) a back (2) on a middle (1) of a watch according to claim 1, characterised in that said positioning means comprise at least one catch formed on the lower part of the ring (4) or on the back (2), said at least one catch being designed to rest in a bed of the middle or of the ring.

3. The device for fastening (100) a back (2) on a middle (1) of a watch according to claim 2, characterised in that said catch formed on the lower part of the ring (4) is formed on the outer wall.

4. The device for fastening (100) a back (2) on a middle (1) of a watch according to any of the preceding claims, characterised in that the ring (4) is made of a polymer material.

5. The device for fastening (100) a back (2) on a middle (1) of a watch according to any of claims 1 to 4, characterised in that the ring (4) comprises on its inner wall at least two inner ribs (45) extending over all or part of the height of the median part (41).

6. The fastening device (100) according to claim 5, characterised in that one of said at least two inner ribs (45) is designed to cooperate with a notch formed in the back (2).

7. The fastening device (100) according to any of claims 1 to 6, characterised in that the ring (4) comprises on its outer wall at least two outer ribs (44) extending over all or part of the height of the median part (41).

8. The fastening device (100) according to claim 7, characterised in that one of said at least two outer ribs (44) is designed to cooperate with a notch formed in the middle (1).

9. The fastening device (100) according to any of claims 1 to 8, characterised in that the ring (4) comprises three inner ribs (45) and three outer ribs (44), the ribs being angularly spaced apart from each other by 60° to 90°.

10. A timepiece characterised in that it comprises a fastening and indexing device (100) according to any of claims 1 to 9.