WO2023083502A1

WO2023083502A1 - Device for magnetically securing two elements of a watch case to one another and watch case comprising said securing device

Info

Publication number: WO2023083502A1
Application number: PCT/EP2022/066181
Authority: WO
Inventors: Joël Allimann; Milan Calic; Jean-Pierre Mignot
Original assignee: The Swatch Group Research And Development Ltd
Priority date: 2021-11-09
Filing date: 2022-06-14
Publication date: 2023-05-19

Abstract

The invention relates to a device (10) for magnetically securing two elements of a watch case to one another, comprising a pair of magnetic modules (11) each one comprising a magnetic-isolation ring (110) and at least one magnet (111), the magnetic modules (11) being respectively intended to be fixed to each one of the elements of the watch case and being configured to collaborate with one another magnetically in order to generate a force of magnetic attraction and a positioning torque that are able to hold the watch case elements against one another in a predetermined angular position.

Description

DEVICE FOR MAGNETIC FIXING OF TWO ELEMENTS OF A WATCH CASE WITH EACH OTHER AND WATCH CASE COMPRISING SUCH FIXING DEVICE

Technical field of the invention

The invention relates to the field of watchmaking, and in particular that of watch cases.

More particularly, the invention relates to a device for magnetically fixing two elements of a watch case together and a watch case comprising said fixing device.

Technology background

[0003] Watch cases have a middle part defining an internal volume receiving a watch movement. On either side of the middle are fixed a crystal and a back to close said internal volume.

[0004] There are a large number of solutions for attaching two elements of the watch case to each other, such as the back with the middle, or the crystal with the middle.

[0005] In particular, the back can be fixed to the middle by screwing, either by the cooperation of a thread of the back with a thread made in the middle, or by the arrangement of screws on the periphery of the back intended to cooperate with tapped holes made in the periphery of the caseband.

[0006] Furthermore, the back and the caseband can be fixed to each other by making a bayonet-type assembly or by tight fitting by press-fitting, that is to say by hunting.

[0007] These solutions are all based on the exploitation of frictional forces, and therefore are likely to pose problems of wear and disturb the tightness of the watch case or the operation of the watch movement by the generation of particles . Summary of the invention

The invention solves the aforementioned drawbacks by proposing a solution making it possible to fix two elements of a watch case together without generating friction forces.

[0009] To this end, the invention relates to a device for magnetic fixing of two elements of a watch case with each other, comprising a pair of magnetic modules each comprising a magnetic insulation ring and at least a magnet, the magnetic modules being respectively intended to be fixed to one and the other of the elements of the watch case and being configured to cooperate magnetically with each other so as to generate a magnetic adhesion force and a positioning torque adapted to hold the watchcase elements against each other, in a predetermined angular position, that is to say a desired angular position.

[0010] Thanks to these characteristics, the force at the origin of the attachment between the two watch case elements and the positioning torque result from the magnetic attraction and not from frictional forces.

[0011] In addition to solving the problems associated with friction, an advantage resulting from the magnetic attraction, and more particularly from the positioning torque, lies in the fact that, when they are fixed to each other, the two watchcase elements are positioned angularly with respect to each other precisely, so that the positioning tolerances are systematically respected.

[0012] In addition, the invention comprising magnetic insulation rings, the operation of the watch movement housed in the watch case does not present any risk of being disturbed.

[0013] Finally, it should also be noted that the present invention solves the problems associated with the release that may occur, for example, when the atmospheric pressure and/or the temperature change so that the air inside the watch case expands significantly.

The present invention therefore makes it possible to magnetically fix two elements of a watch case with each other, in translation and in rotation. In other words, the present invention allows the production of a connection of the recessed type between two watch case elements.

[0015] In particular embodiments, the invention may also comprise one or more of the following characteristics, taken in isolation or in all technically possible combinations.

[0016] In particular embodiments, the rings are intended to be fixed respectively to one and the other of the watch case elements by an external surface, at least one magnet being fixed to an internal surface of each of said rings.

In particular embodiments, each magnetic module comprises a positioning cage comprising at least one housing receiving the at least one magnet.

In particular embodiments, the positioning cage is made of soft ferromagnetic material.

[0019] In particular embodiments, the magnetic modules comprise coatings covering the magnets.

[0020] In particular embodiments, the rings are made of a soft ferromagnetic material.

In particular embodiments, the magnets are made of samarium-cobalt. Optionally, the magnets can be made of Neodymium-Iron-Boron or ferrite.

In particular embodiments, the magnets are made by depositing thin layers directly on the rings, and magnetized according to the predetermined polarities [0023] In particular embodiments, the magnets are configured so that the magnetic adhesion force is greater than 60N.

[0024] In particular embodiments, the magnets are fixed to the rings by gluing.

In particular embodiments, each magnetic module comprises a plurality of magnets distributed angularly on the internal surface of the rings.

In particular embodiments, the magnets are arranged so that two successive magnets have polarities of opposite direction.

In particular embodiments, each magnetic module has mechanical indexing members, the indexing members of one of the magnetic modules being configured to cooperate with the indexing members of the other magnetic module in order to to arrange said magnetic modules according to a predetermined angular position, and/or the indexing members of at least one magnetic module being configured to cooperate mechanically with complementary indexing members with which the watch case elements are respectively provided.

According to another aspect, the present invention also relates to a watch case comprising two elements fixed to each other, and comprising a magnetic fixing device as described above, the two elements each being fixed to a ring of a magnetic module.

In particular embodiments, the two elements comprise indexing members configured to cooperate mechanically with indexing members of at least one magnetic module. [0030] In particular embodiments, the two watch case elements are respectively formed by a back and a middle part, by a bezel and a middle part, by a crystal and a middle part, or by a pusher and a middle part.

Brief description of figures

Other characteristics and advantages of the invention will appear on reading the following detailed description given by way of non-limiting example, with reference to the appended drawings in which:

- Figure 1 shows a perspective view of a magnetic attachment device between two elements of a watch case, said device comprising two magnetic modules cooperating with each other, according to a preferred embodiment of the invention;

- Figure 2 schematically shows a sectional view along the section plane A-A of the magnetic fixing device of Figure 1;

- Figure 3 schematically shows a sectional view similar to that of Figure 2 of a magnetic fixing device according to another embodiment of the invention.

[0032] It is also noted that the drawings are not to scale.

Detailed description of the invention

[0033] Figure 1 shows a magnetic fixing device 10 between two elements of a watch case, said watch case housing a watch movement in a manner known per se by those skilled in the art.

In the present text, the invention is described in an advantageous application in which the watch case elements that the magnetic fixing device 10 makes it possible to fix to each other consist of a bottom and a middle of a watch case. In other non-limiting examples of applications of the invention, the elements of the watch case can be constituted by a bezel and a middle part, a crystal and a middle part, or even by a pusher and a middle part.

The magnetic fixing device 10 comprises a pair of magnetic modules 11, one of which is intended to be fixed to the middle part and the other of which is intended to be fixed to the back. The magnetic modules 11 are configured to cooperate magnetically with each other, as shown in Figures 1 to 3, so as to generate a magnetic adhesion force and a positioning torque adapted to hold the back against the middle in a predetermined angular position, that is to say to secure the back with the middle part and this according to a desired relative angular position.

More specifically, as shown in Figures 1 and 2 in a preferred embodiment of the invention, each magnetic module 11 comprises a magnetic insulation ring 110 intended to be fixed at an outer surface 200 respectively middle and back, and comprises at least one magnet 111 fixed to an internal surface 201 of each of said rings 110.

It is understood here that when the magnetic modules 11 magnetically cooperate with each other, the respective internal surfaces 201 of the rings 110 are oriented towards each other.

In the preferred embodiment of the invention shown in Figures 1 and 2, the rings 110 have an annular shape of revolution around an axis R and the internal surfaces 201 and external 200 of the rings 110 are extend in parallel planes perpendicular to the R axis.

In another exemplary embodiment shown in the sectional view of Figure 3, the rings 110 are configured so that the inner 201 and outer 200 surfaces have a cylindrical shape of revolution around the axis R, said surfaces being coaxial with each other. In still other embodiments of the invention not shown in the figures, the rings 110 are configured so that the inner 201 and outer 200 surfaces are of frustoconical shape and coaxial with the axis R and between them. .

[0042] Alternatively, the rings 110 may not have a shape of revolution, but any other suitable shape, preferably continuous, to be fixed respectively to the caseband and to the back.

Advantageously, the rings 110 are preferably made of a soft ferromagnetic material. This characteristic makes it possible to better channel the lines of magnetic fields generated by the magnets 111, and therefore to give the watch movement improved protection against the effects of said magnetic fields. Another advantage resulting from this characteristic lies in the fact that it makes it possible to confine the magnetic field, and consequently, to concentrate it, which improves the magnetic performance of the 111 magnets.

For example, the rings 110 are made of mu-metal.

Each ring 110 may have a thickness, that is to say the dimension separating the internal surface 201 and the external surface 200, of approximately 1 millimeter.

The magnets 111 are preferably made of samarium-cobalt. Thus, the adhesive force and the positioning torque generated by the magnets 111 are not or are unlikely to vary according to the temperature in the intended field of application.

Alternatively, the magnets 111 can be made of Neodymium-Iron-Boron or ferrite.

As shown in Figure 1 in a preferred embodiment of the present invention, each magnetic module 11 comprises a plurality of magnets 111 distributed angularly around the axis R, on the inner surface 201 of the rings 110. Preferably, in each magnetic module 11, the magnets 111 are arranged so that at least two successive magnets 111 have opposite polarities, as shown in Figure 1.

[0050] More particularly, in FIG. 1, the magnets 111 having the same visual appearance, that is to say either a plain appearance or a hatched appearance, have the same polarity.

As seen in Figure 1 and in a manner known to those skilled in the art, the magnets 111 having opposite polarities cooperate with each other.

The alternating polarization of the magnets 111 makes it possible to increase the magnetic adhesion force and the positioning torque between the magnetic modules 11.

It should be noted that two successive magnets 111 can have polarizations in the same direction if they are separated from each other by a certain distance (not shown in the figures). Such a distance can be useful to form a radial housing, for example intended to receive an indexing member similar to those described below.

In other exemplary embodiments of the present invention, the magnets 111 of each magnetic module 11 can be arranged so as to cooperate magnetically with each other only when the magnetic modules 11 occupy, one with respect to the other, a single predetermined angular position.

[0055] Thus, when the back is fixed to the caseband, they are only oriented with respect to each other according to a single predetermined orientation.

In the preferred embodiment of the invention, the magnets 111 are advantageously configured so that the magnetic adhesion force generated between the magnetic modules 11 is greater than 60N, preferably greater than 100N, for example that it is equal to 130N. [0057] To this end, each magnetic module 11 may have a predetermined number of magnets 111, for example 32 in the embodiment shown in Figure 1. The magnetic adhesion force and the positioning torque are also a function the arrangement of the magnets 111, their dimensions, their shape, as well as the material from which they are made.

By way of example, the magnets 111 can have a thickness of between 0.8 and 1 millimeter.

The magnets 111 can take the form of cylinders of revolution, sectors of rings, or prisms as represented in FIG.

[0060] The magnets 111 are preferably fixed to the rings 110 by gluing, for example by means of a layer of glue or an adhesive film 112.

Alternatively, the magnets 111 can be fixed to the rings 110 by any other suitable fixing solution.

Furthermore, each magnetic module 11 can advantageously comprise a positioning cage comprising housings receiving the magnets 111. The positioning cages can respectively be fixed by gluing on the internal surface 201 of the rings 110. Alternatively, the positioning cages may consist of coatings.

The magnets 111 can also be made by depositing thin layers directly on the rings 110, for example by physical vapor deposition (PVD) process and magnetized according to the polarities desired later. The thin layers can be deposited continuously on the periphery of the rings 110 or discontinuously using structured masks to have the magnets 111 only in the desired areas. It is also conceivable that the magnetic modules 11 include coatings or coatings covering the magnets 111 when they are arranged in positioning cages.

The coatings or coatings advantageously make it possible to form a watertight and airtight plane at the interface between the two magnetic modules when they cooperate with each other. Thus, it is possible to dispense with a possible seal between the back and the caseband.

These coatings or these coatings also make it possible to protect the magnets 111 mechanically against friction linked to a possible rotation of one of the magnetic modules 11 relative to the other, for example which may occur during the separation of the two magnetic modules. 11, particularly necessary during maintenance operations of the watch movement.

The positioning cages make it possible in particular to simplify the method of manufacturing the magnetic modules 11 and to act as a separator for said magnets 111.

Advantageously, the positioning cages can be made of a soft ferromagnetic material so as to guide the lines of magnetic fields generated by the magnets 111, and thus participate in the magnetic insulation of the watch movement.

Advantageously, each magnetic module 11 may have indexing members between them. The indexing members of one of the magnetic modules 11 are configured to cooperate mechanically with the indexing members of the other magnetic module 11 in order to arrange said magnetic modules 11 according to a single predetermined angular position. These indexing members therefore play a keying role in order to secure the caseback to the caseband in a predetermined angular position and participate in guaranteeing the mechanical blocking of the caseback in rotation with respect to the caseband. [0070] The indexing members of one of the magnetic modules 11 can be constituted by a pin, or by any other protruding element, intended to extend towards the other magnetic module 11, in a cavity that the latter comprises, said cavity then forming the indexing members of said other magnetic module 11. The pin and the cavity can advantageously be arranged on the positioning cage of each of the magnetic modules 11.

[0071] Advantageously, the indexing members of each magnetic module 11 can be constituted by a pin and by a cavity, for example arranged diametrically opposite one another, so that the pin and the cavity of one of said magnetic modules 11 cooperate respectively with the cavity and the pin of the other magnetic module 11 .

[0072] Alternatively or in addition, the indexing members of at least one of said magnetic modules 11 are intended to cooperate mechanically with complementary indexing members with which the back and the middle are respectively provided.

More specifically, the indexing members of the magnetic modules 11 preferably comprise, in addition to those described above, a projection extending radially or axially respectively towards the middle part and towards the back, said projections being intended to be engaged in notches extending radially or axially, which comprise respectively the middle and the bottom.

[0074] Alternatively, the projections can extend from the middle part and the back, and the notches can be made in the magnetic modules 11 .

In addition, the projections or notches of each magnetic module 11 can be arranged on the positioning cages or on the rings 110. The rings 110 are fixed by any appropriate means respectively to the back and to the caseband, and are for example engaged against shoulders or in grooves provided for this purpose on the caseband and caseback.

[0077] For example, the rings 110 can be driven or glued.

[0078] The watch case may include a system (not shown in the figures) suitable for separating the case back and the caseband at the request of a user, for example for maintenance purposes.

Such a system can be formed by any suitable technical solution known to those skilled in the art.

More generally, it should be noted that the embodiments considered above have been described by way of non-limiting examples, and that other variants are therefore possible.

[0081] In particular, it may be possible for the magnets 111 of the magnetic modules 11 to be arranged so as to be interposed between the caseband or the back and each of the rings 110, said rings 110 then being intended to rest one against the other when the magnetic modules 11 cooperate with each other.

Furthermore, it is also possible for the magnets to be arranged relative to each other other than according to the arrangement described above.

For example, it is possible for the magnets to be arranged according to a distribution conforming to the Halbach network.

Claims

1 . Magnetic fixing device (10) of two elements of a watch case with each other, comprising a pair of magnetic modules (11) each comprising a magnetic insulation ring (110) and at least one magnet ( 111), the magnetic modules (11) being respectively intended to be fixed to one and the other of the elements of the watch case and being configured to cooperate magnetically with each other so as to generate a force of magnetic grip and a positioning torque adapted to hold the watch case elements against each other, in a predetermined angular position, said device being characterized in that each magnetic module (11) has indexing members mechanical, the indexing members of one of the magnetic modules (11) being configured to cooperate mechanically with the indexing members of the other magnetic module (11) in order to arrange said magnetic modules (11) according to a position predetermined angle, and/or the indexing members of at least one magnetic module (11) being configured to cooperate mechanically with complementary indexing members with which the watchcase elements are respectively provided.

2. Magnetic fixing device (10) according to claim 1, in which the rings (110) are intended to be fixed respectively to one and the other of the watch case elements by an external surface (200), at the least one magnet (111) being fixed on an inner surface (201) of each of said rings (110).

3. Magnetic fixing device (10) according to one of claims 1 or 2, wherein each magnetic module (11) comprises a positioning cage comprising at least one housing receiving the at least one magnet (111). A magnetic fixture (10) according to claim 3, wherein the positioning cage is made of a soft ferromagnetic material. Magnetic fixing device (10) in which the magnetic modules (11) comprise coatings covering the magnets (111). A magnetic fixing device (10) according to one of claims 1 to 5, wherein the rings (110) are made of a soft ferromagnetic material. Magnetic fixing device (10) according to one of Claims 1 to 6, in which the magnets (111) are made of samarium-cobalt. Magnetic fixing device (10) according to one of Claims 1 to 6, in which the magnets (111) are made of Neodymium-Iron-Boron. Magnetic fixing device (10) according to one of Claims 1 to 6, in which the magnets (111) are produced by depositing thin layers directly on the rings (110), and magnetized according to the predetermined polarities. A magnetic fastener (10) according to one of claims 1 to 9, wherein the magnets (111) are configured such that the magnetic adhesion force is greater than 60N. Magnetic fixing device (10) according to one of Claims 1 to 10, in which the indexing members of one of the magnetic modules (11) consist of a projecting element intended to extend towards the other magnetic module (11), in a cavity that comprises the latter, said cavity then forming the indexing members of said other magnetic module (11). Watch case comprising two elements fixed to each other, said case being characterized in that it comprises a magnetic fixing device (10) according to one of claims 1 to 11, in which the - 15 - two elements are each fixed to a ring (110) of a magnetic module (11). Box according to claim 12, in which the two elements comprise indexing members configured to cooperate mechanically with indexing members of at least one magnetic module (11). Watch case according to one of Claims 12 or 13, in which the two watch case elements are formed respectively by a back and a middle part, by a bezel and a middle part, by a crystal and a middle part, or by a pusher and a build.