HK40069259A - Fasteneing device for fastening a back on a middle for a timepiece - Google Patents

Description

Fastening device for a timepiece for fastening a bottom cover to a central piece

Technical Field

The present invention relates to a fastening device for fastening a bottom cover to a middle piece (middle) of a watch.

The invention also relates to a timepiece, in particular a watch, comprising such a fastening device.

Background

The external parts of watches and similar instruments are subject to a number of constraints, in particular water resistance, robustness, appearance, and must be produced in such a way as to avoid irreparably causing any unintentional disassembly in the aftermarket intervention for replacing seals, cleaning, lubrication, and even maintenance.

Moreover, some external or control components must be angularly indexed (indexed) with respect to each other in order to mark the original, set or actuated reference position, or again in order to facilitate reading of the indication or scale, or in order to ensure the continuity of the leave (left) and/or decorative surface. This angular indexing (angular indexing) is often difficult to achieve correctly, in combination with the good tightness of the parts and the perfect water resistance of the seal.

Disclosure of Invention

The present invention is proposed to achieve a tight and fixed assembly of external parts with easy to achieve angular indexing.

To this end, the invention relates to a device for fastening a bottom cover to a centerpiece according to claim 1.

The invention also relates to a timepiece comprising such a fastening device.

Drawings

Other characteristics and advantages of the present invention will become clearer from the following description of a specific embodiment thereof, given purely by way of illustrative and non-limiting example, and the accompanying drawings, in which:

figure 1 is an exploded perspective view of a fastening device according to the invention;

figures 2a and 2b are perspective views of the bottom cover and the central piece, respectively, of the fastening device according to the invention;

figures 3a and 3b are respectively a top view of the bottom cover of the fastening device according to the invention and a cross-sectional view of the bottom cover of figure 3 a;

figures 4a and 4b are respectively a rear view of the central piece of the fastening device according to the invention and a cross-sectional view of the central piece of figure 4 a;

figures 5a and 5b are a perspective view of the assembled fastening device and a cross-sectional view of figure 5a, respectively;

figure 6 shows different possible embodiments of the slot of the fastening device according to the invention.

Detailed Description

The invention is proposed to achieve a sealed and fixed assembly of external components with easy-to-implement angular indexing and in a secure position, by means of a minimum number of components.

Fig. 1-5 b show non-limiting examples of mounting and angular indexing of the bottom cover relative to the watch center piece.

The invention relates to a fastening device 100 for fastening a bottom cover 2 to a watch centre 1, comprising at least one pin 4 integral with the centre, a sealing member mounted on the bottom cover comprising, near its periphery, at least one groove arranged to cooperate with the pin. The bottom cover 2 comprises at least one slot 5 near its periphery, the pin 4 being arranged to slide in the slot 5 between a first position, called insertion position, in which the bottom cover 2 is free, and a second position, called locking position, in which the bottom cover 2 is locked and positioned at an angle with respect to the centerpiece 1, and in that said slot 5 comprises at least one ridge 55 to form a hard point (hard point) and to increase the torque when the pin 4 passes the ridge 55.

The bottom cover 2 is arranged to be switched from a first disassembled insertion position to a second installed and locked position. As shown in fig. 2a, the bottom cover 2 has a shoulder 20 forming a cover 21 and a body 22 arranged to be seated in the hub, wherein the cover 21 is arranged to be completely, partially covered with the hub 1.

In the first, disassembled, inserted position, the core piece 1 and the bottom cap 2 have a first angular orientation with respect to each other.

According to the invention, the bottom cap 2 comprises sealing means, such as an O-ring seal 3, at the interface between the centre piece and the bottom cap, the bottom cap having a slit for receiving the seal. Switching from the first disassembled insertion position to the second installed and locked position under the action of the force exerted by the operator: axial force to overcome the resistance of the O-ring seal and assemble the bottom cap 2 and the center piece 1, and torque to bring the bottom cap 2 and the center piece 1 into the angularly indexed indexing position.

In the second assembled and locked position, the center piece and the bottom cover have a second angular orientation relative to each other that is different from the first angular orientation. The bottom cap 2 and the central member 1 are axially retained by means of a bayonet fitting.

Advantageously, the fixing of the bottom cover and the central element by means of a bayonet fitting, in particular about the axial direction D, is reversible and allows its disassembly. In a particular manner of the invention, this disassembly requires a force from the operator similar to the one applied during assembly, which disassembly preferably requires the use of a special tool, for example a tool cooperating with a hole or a peripheral recess provided on the visible face of the bottom cover 2. Such assembly allows preventing the bottom cover from being removed by the wearer, or after awkward movements or shocks.

According to the invention, the fastening device comprises at least a third component, namely a pin 4, the pin 4 being arranged to be axially interposed between the bottom cover 2 and the central member 1 and to be fastened in rotation with respect to one of them, and the pin 4 comprising at least one elastically deformable zone.

The pin 4 comprises a head 40, a body 41 and a foot 42 and is integral with the central piece. As shown, body 41, head 40 and foot 42 are cylindrical in shape, with body 41 having a diameter smaller than the diameter of head 40 and foot 42. The diameters of the head 40 and of the foot 42 are provided to be identical, but they may well be different, also for different geometries of the pin 4, such as a parallelepiped-shaped body 41 of square cross-section, to be envisaged.

According to a preferred embodiment of the invention, the pin 4 is mounted in a central piece, for which purpose the central piece 1 comprises a machined portion 10 with an opening in the shape of an inverted T for receiving the pin 4, the opening of the machined portion 10 being open on the inside of the central piece so as to make the assembly invisible. Advantageously, the working portion 10 has at least one rib 11, and preferably two ribs, on the wall of the body of the T, so as to perform the assembly by clamping the pin 4 in the working portion 10, the head of which is housed in the head of the T-shaped working portion.

The pins 4 may be made of a different material, such as polyoxymethylene, polyurethane, a polymer based material, or an elastomer, for example, known as Asutane @orhytrel @. The material chosen allows to determine the maximum tightening torque, and therefore the pin 4 allows a tightening torque of about 1.5 n.m, lower than the usual torque for screwing the bottom cap onto the centerpiece for conventional installations. Such a pin 4, preferably in an elastic polymer material or the like, has the advantage of being easy to accommodate in a volume whose free space is limited and it is not possible to safely implant a metal element that is easy to break in this volume.

Thus, the body 41 of the pin 4 is deformable and arranged so that the resistant torques of various moments oppose any relative tangential torque between the bottom cover 2 and the central member 1.

The body 41 of the pin is arranged to cooperate with at least one complementary relief, such as a bump 55, comprised in the bottom cover 2. As shown in fig. 3a, the bottom cover 2 has at least one slot 5 near the periphery of the cover 21, the slot 5 extending along a radius of the bottom cover 2 and having a depth at least equal to half the height of the pin 4 and a width of a size equal to the diameter of the body 41 of the pin 4, so that the pin 4 slides within the slot 5. The tank 5 comprises a back 50, a first end 51 and a second end 52, and two walls 53; the back 50 of the groove is in the form of a slot 54 having a width equal to the dimensions of the head or foot of the pin 4, so as to guide the pin and axially retain the pin 4.

Thus, any passage of pin 4 in slot 5 across ridge 55 generates a resistive torque that tends to oppose relative rotational movement between centerpiece 1 and bottom cap 2.

According to a preferred embodiment, the groove 5 comprises a plurality of ridges 55 arranged to oppose successive resistances during passage of the pin 4. According to the invention, during the rotation between the bottom cover 2 and the central element 1, in the same groove 5, the angular distance between successive ridges 55 decreases to counter the increased resistance. The angular distance between successive humps 55 can also be provided constant to oppose a constant drag torque.

Several configurations for the ridge arrangement are possible. According to a first embodiment, one or more elevations 55 are present on a single side wall of the groove 5. According to a second embodiment, one or more ridges are provided on both side walls of the groove 5, the ridges of each wall being arranged opposite each other. According to a third embodiment, one or more ridges are provided on both side walls of the groove 5, the ridges of each wall being offset from each other. Similarly, the distance between the ridges positioned opposite each other may be varied to provide a progressive resistive torque, as shown in fig. 6.

The first end 51 of the slot 5 forms a space for introducing the pin 4 and the second end 52 forms the stop 6 and maintains the pin 4 in position in the slot 5. For this purpose, the first end 51 has dimensions similar to those of the head or foot of the pin 4, and the second end 52 has dimensions similar to those of the body of the pin 4.

It will be appreciated that the resistance is more pronounced when the number of mating grooves 5, ridges 55 and complementary pins 4 is high. Action can thus be taken with respect to the number of successive ridges, and/or the number of pins and grooves. According to a preferred embodiment of the invention, the bottom cover comprises three slots angularly distributed in a regular manner, and the central piece comprises three complementary pins.

Naturally, the configuration can be reversed, in which at least one slot is machined in the centerpiece and at least one pin is integral with the bottom cover.

During assembly, the operator places the bottom cover on the centerpiece so as to match the foot of the one or more pins with the first end 51 of the one or more slots 5, so that when the operator exerts a translational movement on the bottom cover 2 to place the cover 21 of the bottom cover 2 near the lower edge 13 of the centerpiece 1, the pins are inserted in the slots 5 so that the pins abut against the bottom cover and therefore ensure waterproofness thanks to the seal 3. The pins have a height slightly greater than the distance between the back of the forging (forge) and the cover of the bottom cover, which avoids contact of the bottom cover with the central piece, and there is a gap of 0.02mm to 0.04mm between the bottom cover and the central piece.

The operator then applies a progressive torque to impart a relative rotation between the central member 1 and the bottom cover 2; during this rotation, the operator performing the assembly encounters a first resistance when the body 41 of the pin 4 cooperates with the first bump 55 of the slot 5. Therefore, the resistance torque increases during the relative rotation.

In the first case, the first bump 55 that mates with the pin is the only one. In the second case, the groove comprises several ridges 55, so that the operator provides uneven forces during rotation, accumulating a peak increase in resistive torque during each passage of the hard point to reach a maximum at the angle of indexing. The operator therefore experiences a feeling of increased resistance up to the stop 52.

As shown in the figures, the bottom cover 2 comprises three slots 55 distributed at 120 °, each of which is arranged to cooperate with a pin 4 complementary to the slot. The centerpiece thus comprises three pins distributed at 120 ° and the operator feels that a single hard spot passes when three pins at 120 ° simultaneously pass the protuberance 55.

The waterproofing is present once the bottom cover is placed on the centerpiece and the mechanism according to the invention is arranged so that, as in the case of the previous single bulge, the fixed waterproofing of the seal is ensured once the bottom cover is inserted into the centerpiece and then no loosening occurs without conscious action by the operator.

In fact, very good results are obtained with at least two and preferably three, or even four successive humps, so as to provide a base angular travel sufficient for each hump to pass.

During assembly, the invention requires the successive crossing of several ridges to create an increased resistance, but also upon disassembly, since from the indexed final position (in particular on the mechanical stop), any suddenly applied force results in, in the worst case, crossing a single ridge 55 (without complete disassembly), with a visual offset, but importantly without losing the water-resistance and without the risk of contaminating the inside of the watch. In the example shown, waterproofing is ensured even when the operator crosses three thresholds in succession (which is visible visually due to the offset). To lose waterproofness, the operator must partially remove the bottom cover so that the seal is no longer compressed and the seal is not affected by the rotation of the bottom cover.

According to one embodiment, the distance between each ridge 55 is the same and it works by opposing the same resistive torque.

In an advantageous variant, the distance between each ridge decreases and the operator must apply an increasing torque, as in the example of three ridges 55 in fig. 3 a.

The invention is advantageous because it is perfectly compatible with the gauge dimensions and has the capacity to withstand high resistances, which can reach several n.m.

Furthermore, in the case of a timepiece constrained by a specific large scale (large-scale), the disassembly of the mechanism according to the invention requires to maintain the application of any force of accidental origin during a significant angular travel from 5 ° to 10 ° in order to span a single protuberance in the illustrated example, thereby still ensuring safety if several protuberances follow one another.

According to the invention, the angular indexing is ensured by a second end 52, which second end 52 forms a stop 6 for limiting the stroke.

The invention thus allows to prevent any accidental and unintentional removal of the bottom cover of the centerpiece, for example under the influence of vibrations, of subsequent expansion cycles, of the inadvertent use by the wearer, etc.

Preferably, disassembly requires special non-commercially available tools, which ensures that maintenance is performed by after-market personnel with the required qualifications.

The invention is very suitable for watch cases in which the centre piece and the bottom cover are made of different materials with different coefficients of expansion, or even weak or hard materials (ceramic, sapphire), which do not allow a standard fastening mode. Conventional arrangements include the assembly of a gold centerpiece with a sapphire back cover, or a fully ceramic watch case, cermet combination, or the like.

An important advantage of the present invention is that any contact/friction between the bottom cover and the central member is eliminated and thus residues due to friction and the addition of grease for capturing the residues as is the case in the prior art are prevented.

Another important advantage of the invention is that it provides increased security when opening, since the bottom cover must be at least partially removed, successively through several notches and before any water resistance is lost.

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

In short, the invention allows to provide a fastening device of compact design, which maintains the watertightness of the watch, which is protected against accidental disassembly.

The invention also allows to ensure that the perfect orientation of the component blocking in its position of use is maintained.

The present invention provides a number of advantages:

starting from a first relative angular position between the bottom cover and the central element, ensuring the waterproofing function there, for example once compression of the seal is performed, in the mechanism according to the invention there are a wide range of relative angular values between the bottom cover and the central element, in which the waterproofing is still guaranteed, for example up to several tens of degrees, which is important compared to standard screw-on bottom covers, for example in the case of a central element-bottom cover subassembly, in which screwing off only a few degrees results in loss of waterproofing and requires cleaning and new seals, whereas according to the invention, it is possible to lose waterproofing only after passing through the last notch during disassembly if rotation is continued and the bottom cover 2 is started to be removed from the central element 1;

closing by successive notches with a closing torque of large dimensions for the bottom cover which is both sufficient and acceptable for such an installation, in particular due to the increased number of protuberances distributed in the groove, with a screwing sensation of a progressive increase of the closing torque for the operator up to a desired position, considered as closed position, which is also clearly perceptible;

the opening security is increased due to two factors: the operator needs to provide significant positive energy to pass through the notches and then through several notches before any water resistance is lost.

Claims (15)

1. A fastening device (100) for fastening a bottom cover on a centre piece of a watch, the bottom cover (2) having a shoulder (20) forming a cover (21) and a body (22) arranged to be seated in the centre piece (1), wherein the cover (21) is arranged to be completely partially covered with the centre piece (1); the fastening device comprises at least one pin (4) integral with the central piece, a seal mounted between the bottom cover (2) and the central piece (1); characterized in that said bottom cover (2) comprises at least one slot (5) near its periphery, said pin (4) being arranged to slide in said slot (5) between a first position, called insertion position, in which said bottom cover (2) is free, and a second position, called locking position, in which said bottom cover (2) is locked and positioned angularly with respect to said centerpiece (1); and in that the groove (5) comprises at least one bulge (55) to form a hard spot and to increase the torque when the pin (4) passes the bulge (55).

2. Fastening device (100) for fastening a bottom cover (2) on a centre (1) of a watch according to claim 1, characterised in that said pin (4) is mounted in said centre (1), said pin (4) having a body (41), a head (40) and a foot (42), said body having a diameter smaller than the diameter of said head and/or said foot.

3. Fastening device (100) for fastening a bottom cover (2) on a centre piece (1) of a wristwatch according to claim 2, characterised in that the centre piece (1) comprises a machined portion (10) with an opening in the shape of an inverted T for receiving the pin, the machined portion (10) having at least one rib (11) so as to perform assembly by clamping the pin (4) into the machined portion (10).

4. Fastening device (100) for fastening a bottom cover (2) on a watch centre (1) according to claim 3, characterised in that the opening of the machining portion (10) opens on the inside of the centre (1).

5. Fastening device (100) for fastening a bottom cover on a centerpiece of a watch according to any one of the previous claims, characterized in that said pin (4) is made of a rigid and elastically deformable material, such as polyoxymethylene, polyurethane, a polymer-based material, or an elastomeric material.

6. Fastening device (100) for fastening a bottom cover on a centre of a watch according to claim 1, wherein the pin (4) is machined with the centre (1), the assembly forming an integral element.

7. Fastening device (100) for fastening a bottom cover on a centre piece of a watch according to any one of claims 1 to 6, characterised in that said groove (5) extends along a radius of the bottom cover (2) and has a depth at least equal to half the height of the pin (4) and a width similar to the diameter of the body (40) of the pin, so that the pin slides within the groove (5).

8. The fastening apparatus (100) according to any one of claims 1 to 7, wherein the slot (5) comprises a back (50) in the shape of a slot (54), a first and a second end (51, 52), and two walls (53), the slot (54) corresponding to the dimensions of the head (40) or the foot (42) of the pin, so as to guide the pin and axially retain it.

9. The fastening apparatus (100) according to claim 8, wherein the first end (51) forms a space for introducing the pin (4) and the second end (52) forms a stop and holds the pin in place.

10. The fastening apparatus (100) according to claim 8 or 9, wherein the first end (51) has dimensions similar to the head or the foot of the pin (4) and the second end (52) has dimensions similar to the body (40) of the pin.

11. The fastening apparatus (100) according to any one of claims 8 to 10, wherein the ridge (55) is formed on one of the two walls (53) of the groove (5).

12. The fastening apparatus (100) according to any one of claims 1 to 11 wherein the slot (5) comprises a plurality of ridges (55), the distance between each ridge (55) being the same.

13. The fastening apparatus (100) according to any one of claims 1 to 11 wherein the slot (5) comprises a plurality of ridges (55), the distance between each ridge (55) being reduced.

14. The fastening apparatus (100) according to any one of claims 1 to 13, characterized in that it comprises at least three pins (4), said at least three pins (4) being angularly distributed on the bottom cover and being arranged at regular intervals.

15. Timepiece, characterized in that it comprises a fastening device (100) according to any one of claims 1 to 14.