EP2989505B1 - Method for attaching a movement inside a case - Google Patents

Description

The present invention relates to a device and a method for fixing a movement in a watch case, and in particular a movement in a case for a diving watch.

BACKGROUND TECHNOLOGY

In the field of watchmaking, the plates on which the movements are arranged generally contain a net, that is to say an upper edge which is provided for their attachment to the housing. For this purpose, the net can be fixed with flanges and screws that are inserted into threads, and thus pressed against a shoulder of the middle part. While this type of fastening has the advantage of being reliable and reversible, it nevertheless has the disadvantage of being relatively complex to implement because of the different manipulations required for the screws and the flanges, which seriously affects the productivity. and is thus not suitable for the manufacture of watches intended to be produced on a large scale.

The document US2002 / 0131332 of the Applicant discloses an alternative method of fixing a movement that does not need to be provided with thread or flanges, but still uses fastening screws. A first series of screws is introduced into through holes arranged at the periphery of the movement to assemble the latter to a bezel, while the bottom is then assembled to the same bezel with a second series of screws. So if the central element for this type of fixation is no longer the middle part, but the bezel of a watch, the same disadvantages in terms of productivity nevertheless remain, they are even amplified because of the increased number of screwing operations that are required when mounting the movement.

This is why one sometimes favors fixing methods by hunting, usually using intermediate parts such as casing circles, which allow the rest to adjust small movements given and calibrated in larger housings.

The solution described in the patent document EP1046967 of the Applicant concerns for example such a mode of fixing a movement using a casing ring made of a plastically deformable material to allow its radial or axial adjustment in a specific position relative to the housing.

Whatever the method of attachment chosen, the lower rim of the thread is always brought into abutment against a part of the middle part, and the shape of the bottom of the case, integral or not with the middle part, matches that of the lower part of the movement, to close machining tolerances. The document US4558955 discloses such a solution for fixing a movement, according to which the latter is housed directly in a recess of a monobloc center-case and is held axially between the bottom of this recess, against which it bears, and the dial, retained by the ice. The disadvantage of this type of attachment mode is that any deformation of the bottom, especially in the context of underwater use, is replicated directly on the plate, and the latter is particularly sensitive.

To avoid any inadvertent deformation of the component parts of the watch, an alternative is, especially for plastic watches, to use reinforced structures containing for example metal skeletons or other types of materials to stiffen the housing. This alternative is however not possible if one wishes to maintain aesthetic properties for the housing, especially if it is desired that it remains at least partially transparent.

Otherwise double bottom structures are also known for watches housing other internal modules in addition to the movement. The document EP0670532 for example a watch provided with a pressure sensor, and describes a movement conventionally assembled to a middle part by means of a casing ring, while an internal bottom houses the pressure sensor, covered by the bottom of the case. Such a structure, however, has the disadvantage of adding a considerable thickness to the housing and also slow down the rate of assembly due to the duplication of assembly operations for each fund.

There is therefore a need for a method and a fixture for movement in a housing free of these known limitations.

SUMMARY OF THE INVENTION

For this purpose, the present invention relates to a timepiece comprising a housing in which is housed a movement comprising a lower peripheral support surface, the housing comprising a middle part to which are assembled respectively a bottom and an ice. The timepiece is characterized in that it furthermore comprises a clamping element provided with a lower retaining surface and that the movement comprises an upper peripheral support surface, the lower retaining surface of the element of clamping and the upper peripheral support surface being in mutual contact, and that the bottom comprises an annular peripheral shoulder, against which is affixed the lower peripheral bearing surface of the movement, which is compressed between its lower peripheral bearing surface and its upper peripheral support surface respectively by the annular peripheral shoulder of the bottom, and the lower retaining surface of the clamping element.

The present invention also relates to a base for such a timepiece, taken separately, characterized in that it comprises a recessed central portion of variable thickness and an annular peripheral shoulder of constant thickness.

• introduction du mouvement dans le boîtier côté cadran;
• apposition d'une surface d'appui périphérique inférieure du mouvement contre un épaulement périphérique annulaire du fond, puis
• serrage dudit mouvement contre le fond par un élément de serrage venant en appui contre une surface d'appui périphérique supérieure du mouvement, de telle sorte que le mouvement est comprimé entre sa surface d'appui périphérique inférieure et sa surface d'appui périphérique supérieure par respectivement l'épaulement périphérique annulaire du fond, et une surface inférieure de retenue de l'élément de serrage.

Finally, the present invention also relates to a preferred method of assembly for obtaining such a timepiece. The method is characterized in that the mounting of the movement in the housing comprises the following steps:

• introduction of the movement in the case on the dial side;
• apposition of a lower peripheral bearing surface of the movement against an annular peripheral shoulder of the bottom, then
• clamping said movement against the bottom by a clamping member abutting an upper circumferential bearing surface of the movement, such that movement is compressed between its lower circumferential bearing surface and its upper peripheral support surface by respectively the annular peripheral shoulder of the bottom, and a lower retaining surface of the clamping element.

An advantage of the present invention is to better absorb possible deformations of the bottom, for example during consequent changes in pressure or temperature, thanks to the complete dissociation of the inner surface of the bottom relative to the movement. Thus it avoids exerting any negative torsional stress on the plate and therefore on all the elements of the movement, including the axes and bridges.

According to the preferred method of assembly, the movement is introduced from the top of the housing, dial side, which avoids any operation of turning the housing during assembly, and thus advantageously increases the mounting rates.

BRIEF DESCRIPTION OF THE FIGURES

• la figure 1 montre une vue en coupe d'un schéma de principe de l'assemblage d'un mouvement dans un boîtier selon un mode de réalisation préférentiel de l'invention;
• les figures 2A et 2B, montrent des vues respectivement de dessus et en coupe d'une montre de plongée utilisant la méthode d'assemblage selon un mode de réalisation préférentiel;

Other characteristics and advantages of the invention will emerge more clearly from the detailed description and the drawings, given by way of example and with non-limiting scope, in which:

• the figure 1 shows a sectional view of a block diagram of the assembly of a movement in a housing according to a preferred embodiment of the invention;
• the Figures 2A and 2B show respectively top and sectional views of a diving watch using the method of assembly according to a preferred embodiment;

DETAILED DESCRIPTION

The figure 1 illustrates a sectional view of a timepiece according to a preferred embodiment of the invention in the assembled position, the movement 3, which is subject to a control rod 7 and which drives the needles 30 above a 6, dial is assembled in the housing 2 according to a method corresponding to a preferred embodiment of the invention. According to this preferred embodiment, the housing contains a monobloc bottom-middle, that is to say that the bottom portion 4 is made in one piece with the middle part forming the central portion of the housing 2. Such monobloc part simplifies the assembly process of the movement 3 by eliminating an assembly step, the movement 3 can in this case be introduced directly from the top of the housing 2, that is to say, dial side, without the need to mount next the bottom nor to return the housing 2 to introduce the movement. However, it will be understood that the assembly method of the invention also applies to a bottom 4 assembled to the middle 20 by driving, screwing or gluing or any other usual method of fixing. Nevertheless, the step of assembling the bottom 4 to the middle part 20 will preferably be carried out before the introduction movement 3 in the housing, so that the latter is always introduced dial side.

On the edge of its inner surface, the bottom 4 comprises a peripheral annular shoulder 41, of a first width (L) , on which the movement 3 bears, and a recessed central portion 40 of depth (d) . The lower peripheral support surface 31 of the movement 3 is superimposed at least partially on an upper peripheral support surface 32 of the movement 3, of a second width (1) , which is gripped by the lower retaining surface. a clamping element, constituted here by a portion 52 of the heel 51 of the ice 5, of a third width (T) , a lower surface of which bears against the upper peripheral support surface 32 of the movement 3 .

According to a preferred embodiment, a first width L of the lower circumferential bearing surface 31 of the movement 3 greater than the second width 1 of the upper bearing surface 32 is chosen, but at the same time compensates for this by a third width T the bead 51 selected to be greater than the first width L of the peripheral bearing surface 31 of lower movement 3, to have a pinch and a symmetrical compression of the movement 3 at its periphery which generates the minimum torque.

At the level of the annular peripheral shoulder 41, the thickness of the bottom is constant and equal to (E) , while this variable thickness over the entire hollow central part 40, and minimum in the center of the bottom 4, a value of (e) . As can be seen from the figure 1 we have the equality e + d = E. The recessed central portion 40 allows the bottom 4 to deform slightly, especially at its center, when forces due to pressure, indicated by the arrows (P), are exerted on the housing 2, for example during immersion at a depth greater than ten meters or more, an additional bar is applied to the entire external surface of the case - which is equivalent to twice the surrounding pressure - without affecting the movement, which is caught between its lower 31 and upper 32 peripheral support surfaces but is not in contact with the bottom 4 in its recessed central portion 40. Thus the housing 2 is robust for pressure values such that the curvature of the bottom not reverse to the point that the recessed central portion 40 of the bottom 4 is brought to be again in contact with the movement 3. To facilitate the torsional deformation of the bottom 4 and avoid the transmission of stresses at the peripheral nipping regions of the movement 3, the shape of the recessed central portion 40 of the bottom 4 is chosen to be preferably parabolic.

In the context of the invention, the movement 3 has a diameter of preferably between 25 and 40 millimeters, and the first width L of the annular peripheral shoulder 41 of the bottom 3 is in this case chosen to be preferably between 2 and 5 millimeters. More generally, the first width L of the peripheral shoulder 41 of the bottom is chosen to be between a quarter and a tenth of the value of the diameter of the movement 3, to improve the pinching effect at its periphery while also allowing the bottom 4 to deform more easily under the effect of external forces of stress. For maximum thickness E of the bottom 4 of between 3 and 5 mm and a minimum thickness of said bottom e of between 2.5 and 4 mm, the housing 2 can then withstand a pressure of about 35 bars to a minimum.

On the figure 1 , it can be seen that the heel 51 of the ice 5 is brought into contact on a bearing 21 of the middle part 20 in the extension of the portion 52 resting on the upper peripheral bearing surface 32 of the movement 3. According to this method of preferential embodiment, the step of clamping the movement 3 between its lower peripheral portions 31 and upper 32 is carried out together with the mounting of the ice 5 on the middle part 20, preferably by ultrasonic welding. The assembly structure obtained has the advantage of relieving the torsional stresses at the welded part thanks to the upper peripheral bearing surface 32 of the movement 3 which extends axially the scope of the middle part 21, and thus improves the strength and durability of the connection between the welded parts.

According to the preferred embodiment illustrated, the fact that the lower bearing surfaces 31 and upper 32 are partially superimposed also makes it possible to preserve the integrity of the movement 3, avoiding the application of a torque in torsion which tends to to deform due to forces of opposite constraints and similar standard exerted on areas whose distance from the center would be very different.

This preservation of the movement with respect to the deformations of the case is further accentuated by the fact that according to the preferred embodiment illustrated, the heel 51 of the ice, whose third width Test preferably between 4 and 8 millimeters, is entirely superimposed on the above the annular peripheral shoulder 41, to further improve the pinch effect. For reasons of symmetry and therefore optimum distribution of the stresses to minimize the torsional torque generation, the third width T of the heel 51 will preferably be chosen to be at most equal to twice that of the first width L of the annular peripheral shoulder 41.

We can note that movement 3 of the figure 1 has been shown without a net, because the latter is not used, unlike traditional movements, to provide an abutment or hunting surface when assembled in the housing 2.

The Figures 2A and 2B respectively illustrate a view from above and in section along an axis AA of a preferred embodiment for the mode of assembly of the movement 3 in a housing 2 according to the invention for a timepiece 1 corresponding to a diving watch .

The Figure 2A is a top view of the diving watch, showing the case 2, as well as the ice 5 surmounted by a telescope 8. Figure 2B makes it possible to distinguish the parts inside the casing 2, and in particular the movement 3 conventionally provided with a net 33 on its part higher. This thread 33 is however not provided to ensure the axial retention of the movement 3 in the housing 2, this function being fulfilled by the annular peripheral shoulder 41 of the bottom 4 and the portion 52 of the heel 51 of the ice 5 which take sandwiching respectively the lower peripheral bearing surfaces 31 and 32 upper movement 3 for its clamping when the ice 5 is welded to the scope 21 of the middle part 20 at the heat sealing zone 22 materialized by the small beak descending to the periphery Heel 51. Thus, together with the operation of heat sealing the ice to the middle 20, the movement 3 is clamped between a portion 52 of the heel 51 of the glass 5 and the annular peripheral shoulder 41 of the bottom 4. The bezel 8 may be mounted on the ice later 5.

As can be seen from the Figure 2B according to this preferred embodiment, which is used for a movement of a diameter of about 33 millimeters, the lower peripheral bearing surface 31 of the movement, of a first width L equal to 4 millimeters just like that of the annular peripheral shoulder 41 of the bottom 4 which compresses it by the bottom 4, and the upper peripheral bearing surface 32 of the movement, of a second width l equal to 2.5 millimeters just as the portion 52 of the heel 51 of the ice 5 which compresses it from above, are integrally superimposed, so that the nip thus created generates the minimum torque at the periphery of the movement. Similarly, the heel 51 has a third width T of 7 to 8 millimeters and is superimposed integrally with the annular peripheral shoulder 41 for the same reasons of minimization of the torsional deformation stresses on the movement 3. For reasons of symmetry and to relieve stresses on the heat sealing zone 22, the bead 51 will comprise an inwardly extending portion opposite to that of the heat sealing zone 22 relative to the portion 52 squeezing the motion at its surface. upper support 32.

According to this preferred embodiment, the thickness E of the bottom is about 3 millimeters and its minimum thickness is 2.5 millimeters, revealing a notch of about 0.5 millimeters in depth in the center. The recessed central portion 40 of the bottom 4 has a form of parabolic preference to facilitate the deformation of the bottom 4 and optimize the distribution of stress forces exerted on the bottom of the housing 2. Still for reasons of symmetry and optimal distribution pressure forces resulting from the pressure, the ice 5 preferably has a shape and a thickness similar to that of the bottom 4.

In the context of the preferred embodiment of the invention, the preferential assembly structure obtained after the clamping operation of the movement 3 between its lower and upper peripheral support surfaces 31 and 32 directly involves a portion 52 of the heel 51. ice 5 as a lower surface for retaining a clamping element, and a laser welding operation, which not only saves a dedicated part for the axial retention of the movement 3, pressed against the shoulder annular peripheral 41 of the bottom 4 by the ice 5, acting as a clamping element, but also to dispense with a dedicated fixing operation of the movement 3, since the latter is fixed together with the bottom when the ice 5 is welded to the middle part 20. The reduction in the number of parts and assembly operations necessary for the fixation of the movement thus makes it possible jointly to reduce the production costs. n and increase productivity. Instead of laser welding, however, other methods of attachment could be envisaged, for example by brazing, gluing, or driving without departing from the scope of the invention, and moreover, according to an alternative embodiment not shown, one could envisage also imagine that an intermediate piece, such as a ring, is interposed between the ice 5 and the movement 3, or that another piece used to perform the clamping is directly assembled to the middle part 20 without involving the ice 5 , such as an L-shaped section of which a first side, which would include the lower clamping surface, would be affixed above the net of the movement 3 and the second side would be driven in a circular rib of the middle part 20.

Note also that the parts assembled in the context of the present invention, and in particular the bottom 4, are preferably made of a plastic material. The present invention, however, also includes cases 2 including diving watches comprising funds 4 made of steel or metal, whose rigidity is certainly greater, but which are not however free of any deformation for very high pressures. List of references 1 Timepiece 2 Housing 20 shoulders 21 Scope of the middle 22 Heat-sealing zone 3 Movement 30 Needles of the movement 31 Lower annular bearing surface of the movement 32 Upper annular support surface of the movement 33 Net of the movement 4 Background 40 Hollow part of the bottom 41 Annular shoulder of the bottom 5 Ice cream 51 Heel of the ice 52 Portion of the heel of the ice resting on the surface 32 of the movement 6 Dial 7 Control rod 8 Glasses E Thickness (maximum) of the bottom e Thickness (minimum) of the bottom d Depth of the recess of the central part 40 The First width of the lower support surface I Second width of the upper support surface T Third width of the heel of the ice 51 AA Cutting axis of the Figure 2A

Claims (10)

1. Timepiece (1) including a case (2) which accommodates a movement (3) including a lower peripheral bearing surface (31), said case (2) including a case middle (20) to which are respectively assembled a back cover (4) and a crystal (5), said timepiece (1) further including a clamping element provided with a lower retaining surface and that said movement (3) including an upper peripheral bearing surface (32), said lower retaining surface of said clamping element and said upper peripheral bearing surface (32) being in mutual contact, and the back cover (4) including an annular peripheral shoulder (41) of constant thickness against which is affixed said lower peripheral bearing surface (31) of said movement (3), and a hollow central portion (40) of variable thickness and parabolic shape, said movement (3) being compressed between said lower peripheral bearing surface (31) and said upper peripheral bearing surface (32) of said movement (3), said lower (31) and upper (32) peripheral bearing surfaces of said movement (3) being at least partially superposed, respectively by said annular peripheral shoulder (41) of said back cover (4), and said lower surface of said clamping element, characterized in that the hollow central portion (40) is of variable thickness and parabolic shape.
2. Timepiece (1) according to the preceding claim, characterized in that said lower retaining surface of said clamping element is formed by a portion (52) of the heel (51) of said crystal (5).
3. Timepiece (1) according to claim 2, characterized in that the back cover (4) and the case middle (20) form a one-piece part.
4. Timepiece (1) according to any of claims 2 or 3, characterized in that said base (51) of said crystal (5) is entirely superposed on said annular peripheral shoulder (41) of said back cover (4).
5. Timepiece (1) according to any of claims 2 to 4, characterized in that said movement (3) has a diameter comprised between 25 and 40 millimetres, and in that the peripheral shoulder (41) of said back cover (4) extends over a first width (L) of at most 5 millimetres, said base (51) of said crystal (5) over a third width (T) of at most 8 millimetres, and said portion (52) of said base (51) over a second width (/) of at most 4 millimetres.
6. Back cover (4) for a timepiece (1) according to any of claims 1 to 5, characterized in that the back cover includes an annular peripheral shoulder (41) of constant thickness and a hollow central portion (40) of variable thickness and parabolic shape.
7. Back cover for a timepiece (1) according to claim 6, the maximum thickness (E) of said back cover being comprised between 3 and 5 mm, and the minimum thickness (e) of said back cover being comprised between 2.5 and 4 mm.
8. Back cover for a timepiece (1) according to any of claims 6 or 7, characterized in that the width of said peripheral shoulder (41) is comprised between a quarter and a tenth of the value of the diameter of the movement.
9. Assembly method for a timepiece (1) according to any of claims 1 to 5, characterized in that the assembly of said movement (3) in said case (2) includes the following steps:

   - inserting said movement (3) in said case (2) from the dial side

   - affixing a lower peripheral bearing surface (31) of said movement (3) against an annular peripheral shoulder (41) of constant thickness of said back cover (4), said back cover (4) further including a hollow central portion (40) of variable thickness and parabolic shape, and then

   - clamping said movement (3) against said back cover (4) by means of a clamping element abutting against an upper peripheral bearing surface (32) of said movement (3), such that said movement is compressed between said lower peripheral bearing surface (31) of said movement (3) and said upper peripheral bearing surface (32) of said movement (3), said lower (31) and upper (32) peripheral bearing surfaces of said movement (3) being at least partially superposed, respectively by said annular peripheral shoulder (41) of said back cover (4), and a lower retaining surface of said clamping element.
10. Assembly method for a timepiece (1) according to claim 9, characterized in that the back cover (4) and the case middle (20) form a one-piece part, said lower retaining surface of said clamping element is formed by a portion (52) of the heel (51) of said crystal (5) and in that said clamping step is performed jointly with the step of assembling said crystal (5) to said case middle (20).

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