CH717170A2 - Mechanical clockwork bearing fitted with a damping part. - Google Patents

Abstract

The invention relates to a mechanical clockwork bearing (1) intended to be fitted on a mechanical movement (10) of a timepiece, the bearing (1) comprising, coaxial around a common axis of rotation (D ), at least one internal cage (4) and at least one external cage (5) forming a circulation track (20), as well as a plurality of mobiles (12) sliding or rolling in the circulation track (20), during a relative movement between said inner cage (4) and said outer cage (5) which guide them and of which at least one of said inner cage (4) and outer cage (5) is a dynamic cage, at least one part of the bearing (1) being made of an elastic metallic material with high damping capability, the damping factor of which is greater than 10%, preferably greater than 30%.

Description

Field of the invention

The invention relates to a mechanical clockwork bearing provided with a damping part.

[0002] The invention also relates to a timepiece movement comprising at least one such bearing.

[0003] The invention relates to the field of clockwork mechanisms and more particularly to rotational guides.

Background of the invention

[0004] Self-winding mechanical watches are generally equipped with oscillating winding masses for winding the barrel spring. In order to allow the oscillating mass to pivot, a ball bearing is most often used as the suspension.

[0005] The components of a bearing are usually metallic, in particular steel, brass or a copper-beryllium alloy.

However, such ball bearings generate noise in the form of acoustic waves, which can be annoying for the wearer of the watch. The origin of these noises is diverse, in particular because of the roughness of the contacts between the bodies, shape defects during manufacture or due to wear of the bodies by friction.

In order to solve this problem, attempts have been made, for example in application EP3460275, to reduce the contact surfaces between the balls and the other bodies of the bearing. However, such a bearing requires a large quantity of lubricant, the viscosity of which is higher, which can limit the winding capacity. The lubricant is also visible from the outside of the watch, which can cause unpleasant unsightly effects.

Summary of the invention

The object of the invention is to provide a mechanical bearing, in particular a ball bearing, which avoids the aforementioned problems.

To this end, the invention relates to a mechanical clockwork bearing intended to be arranged on a mechanical movement of a timepiece, the bearing comprising, coaxial about a common axis of rotation, at least one internal cage and at least one external cage forming a circulation track, as well as a plurality of moving parts sliding or rolling in the circulation track, during a relative movement between said internal cage and said outer cage which guide them and of which the 'at least one of said inner cage and outer cage is a dynamic cage.

The invention is remarkable in that at least part of the bearing is made of an elastic metallic material with high damping capability, the damping factor of which is greater than 10%, preferably greater than 30% .

Thanks to such a bearing, the vibrations due to the movement of the oscillating weight are significantly attenuated. Thus, wearing a self-winding watch does not cause an unpleasant sensation, especially on the wrist.

[0012] In addition, the use of a metallic material makes it possible to avoid the problems of depreciation in synthetic material, such as the absorption of humidity or the release of gas. In addition, a metallic material is more qualitative and noble in a higher end timepiece, and it is generally much more resistant.

[0013] According to a particular embodiment of the invention, the metallic material has a tensile strength greater than 100 MPa, preferably greater than 400 MPa, or even 600 MPa.

According to a particular embodiment of the invention, the material is to be chosen from the following list: an alloy of at least 80% manganese and copper, an alloy of at least 80% copper, preferably 82%, aluminum and nickel, preferably 12% and 5%, an alloy of at least 80% iron, preferably 85%, chromium and aluminum, preferably 12% and 3%, an alloy of at least 60% iron, preferably 65%, and cobalt, preferably 35%, an alloy of at least 90% iron, preferably 95%, aluminum and carbon, preferably 6% and 0.2%, an alloy of at least 70% manganese, preferably 73%, copper, nickel and iron, preferably 20%, 5% and 2%, the alloy having a Vickers hardness index of minus 130, and a nitinol type alloy comprising at least 50% nickel, preferably 55% and titanium, preferably 45%.

According to a particular embodiment of the invention, the bearing comprises a first damping part intended to be positioned between one of said cages and a bridge of the automatic movement winding system, the first damping part forming the part of the bearing made of an elastic metallic material with high damping capability.

[0016] According to a particular embodiment of the invention, the bearing comprises a second damping part intended to be positioned between one of said cages and means for maintaining the bearing on the movement, such as a nut or a screw , the second damping part forming the part of the bearing made of an elastic metallic material with high damping capability.

According to a particular embodiment of the invention, the first and / or the second part are washers.

According to a particular embodiment of the invention, the first and / or the second part are tubes.

According to a particular embodiment of the invention, the outer cage is made in the damping material.

According to a particular embodiment of the invention, the internal cage is made in the damping material.

According to a particular embodiment of the invention, said mobiles are balls made of a metallic material with high damping power.

The invention also relates to a timepiece movement comprising at least one such bearing.

Brief description of the drawings

Other characteristics and advantages of the invention will become apparent on reading the detailed description which follows, with reference to the accompanying drawings, where: FIG. 1 schematically shows a sectional view of part of a mechanical movement with automatic winding, the movement being provided with a ball bearing according to a first embodiment of the invention; FIG. 2 schematically shows a sectional view of part of a mechanical movement with automatic winding, the movement being provided with a ball bearing according to a variant of the first embodiment of the invention, FIG. 3 is a schematic representation of a washer-shaped damping part and a tube-shaped damping part, Figure 4 is a graph showing the damping factor of certain materials and alloys as a function of the tensile strength of the materials, this graph having been published in the article "Development and application of high damping alloys for noise and vibration control" (ICSV 14, 9-12july, 2007, Cairns AU) by F. Yin.

Detailed description of the preferred embodiments

The invention relates to a mechanical bearing 1de automatic winding for a timepiece movement 10, for example as shown in Figures 1 and 2.

In Figures 1 and 2, the movement 10 includes an axis 2 for a needle display system, a bridge 3 of automatic winding system on which are assembled various cogs and elements of the movement 10, as well as a ball bearing 1 fixed on the bridge 3du the automatic winding system by holding means, such as a screw 7 for FIG. 1 or a nut 9 for FIG. 2.

This bearing 1comporte, conventionally, coaxial around a common axis of rotation D, at least one internal cage 4, 14 and at least one external cage 5, 15. The axis 2 of the needle display system and the axis D are collinear, axis 2 of the display system being assembled on the other side of the bridge from the bearing 1.

Assembled, these internal cages 4, 14 and external 5, 15form a circulation track 20, in which a plurality of mobile 12, 13, here balls, slide or roll during a relative movement between the internal cage 4, 14 and the outer cage 5, 15. The circulation track 20 is an internal duct of the bearing, which retains the moving parts 12, 13 while allowing them to move in the duct.

The invention is illustrated in the figures in the simplified case of an internal cage 4, 14unique and of an external cage 5, 15unique, the person skilled in the art can extrapolate it to a bearing comprising several stages, of which each comprises a movement track 20de mobiles 12, 13 between an internal cage 4, 14 and an external cage 5, 15. The external cage 5, 15 is constituted by a single external ring. Of course, the outer cage 5, 15 can also be made up of several juxtaposed outer rings.

The bearing 1 is assembled on the bridge 3. In Figures 1 or 2, the mechanical bearing 1 includes an axial central passage 16 for the passage of the screw 7 or the nut 9. The screw 7 is screwed into a stud 8 retained by a collar 18 under the bridge 3du the winding system, while the nut 9 is screwed around the stud 8. The screw 7 or the nut 9, as well as the stud 8 are arranged along the axis D of the bearing 1. The stud 8 inserted in the passage 16 under the ball bearing 1, while the screw 7 or the nut 9 is inserted in the passage 16 from the top of the bearing 1.

At such a stage comprising a circulation track 20, at least the internal cage 4, 14, or the external cage 5, 15, is a dynamic cage, that is to say it is movable during normal operation of the bearing relative to a static component of a timepiece movement, such as plate, bridge 3, or the like. In a particular variant not shown, the internal cage 4, 14 is a dynamic cage and the external cage 5.15 is a dynamic cage. In another variant illustrated by FIG. 2, the internal cage 4, 14 is a static cage, and the external cage 5, 15 is a dynamic cage. In yet another variant, not illustrated, the internal cage is a dynamic cage, and the external cage 5, 15 is a static cage.

Such bearings 1 are designed for horological applications, and therefore have very small dimensions: diameter between 1.6mm and 20.2mm, terminals included; diameter of the balls when the mobiles are balls, between 0.2mm and 0.6mm, terminals included; thickness of the internal cage 4.14 according to the direction of the axis of rotation between 0.4mm and 1.5mm, including terminals, and less than or equal to 1.0mm when the moving parts are balls with a diameter of between 0.2m and 0.6mm, terminals included; thickness of the outer cage 5.15 according to the direction of the axis of rotation between 0.4mm and 1.5mm, including terminals, and less than or equal to 1.0mm when the moving parts are balls with a diameter of between 0.2m and 0.6mm, terminals included.

More particularly, the smallest bearings have balls with a diameter of 0.2mm, for a diameter of 1.6mm, their thicknesses are between 0.4 and 1mm.

And the largest bearings have balls with a diameter of up to 0.6mm, for a diameter of 5.7 to 20.2mm, their thicknesses go up to 1.5mm.

The bearing 1illustré in Figures 1 or 2 is a ball bearing according to the invention, with a diameter of 5.7mm, a ball diameter of 0.5mm, a thickness of the internal cage of 1.0mm, and a thickness of the cage 1.0mm external.

In the first embodiment of Figures 1 and 2, the bearing 1 includes a first damping part 6positioned between the internal cage 4, 14 and the bridge 3du automatic winding system. The first part 6 is arranged on a plate 19 of the bridge of the automatic winding system. The bearing 1 furthermore comprises a second damping part 17 positioned between the internal cage 4, 14 and the means for maintaining the bearing 1 on the movement 10, that is to say the screw 7 or the nut 9. The second part 17 is arranged in a housing 21 hollowed out in the upper face of the internal cage 4, 14. The damping parts are washers, or flat discs, provided with a central opening allowing the passage of the screw, the nut or the stud according to its layout. The second part is smaller than the first because the screw or nut is narrower. The damping parts are concentric around the axis of the bearing.

In Figure 3, there is shown a damping part 6, 7du first embodiment, which is in the form of a washer. A damping piece 22 in the form of a tube is also shown. The tubes are elongated hollow pieces and arranged in a manner similar to washers. Tubes can in fact be used to absorb vibrations according to another embodiment.

The damping parts 6, 17, 22 are made of an elastic metallic material with high damping capability, the damping factor of which is greater than 10%, preferably greater than 30%. Such a damping factor provides sufficient comfort for the wearer of the timepiece. Thus, these damping parts absorb the vibrations generated by the ball bearing 1.

In dynamic mechanical analysis, a body is subjected to an oscillatory stress or deformation. The damping factor δ, also called the loss factor, characterizes the damping capacity of a material according to the following equation: where Ediss is the energy dissipated by the material during an oscillation cycle, and Emax is l maximum strain energy stored by the material during an oscillation cycle.

The metallic material is preferably to be chosen from the following list: an alloy of at least 80% manganese and copper, an alloy of at least 80% copper, preferably 82%, aluminum and nickel, preferably 12% and 5%, an alloy of at least 80% iron, preferably 85%, chromium and aluminum, preferably 12% and 3%, such as the commercial alloy "Silentalloy", an alloy of at least 60% iron, preferably 65%, and cobalt, preferably 35%, such as the commercial alloy "Gentalloy", an alloy of at least 90% iron, preferably 95%, aluminum and carbon, preferably 6% and 0.2%, an alloy of at least 70% manganese, preferably 73%, copper, nickel and iron, preferably 20%, 5% and 2%, such as the commercial alloy "M2052", the alloy having a Vickers hardness index of at least 130, and a nitinol type alloy comprising at least 50% nickel, preferably 55% and titanium, preferably 45%.

However, other metallic materials are also possible, in particular alloys having the same physical properties, in particular concerning the damping factor.

M2052 or nitinol type materials are particularly suitable for damping parts, such as the washers or tubes described above. Nitinol has particular qualities of shape memory and super elasticity.

In addition, the metallic material has a tensile strength greater than 100 MPa, preferably greater than 400 MPa, or even 600 MPa. Thus, the bearing part is more resistant, and wears less quickly than with other materials. Polymer damping materials, as described in application EP3418595, have a much lower modulus of elasticity, so that play can occur between the ball bearing and the bridge. Such play can cause contact between the bearing and the bridge, or other components of the movement.

FIG. 4 shows a graph 30 in which examples of damping factor values as a function of the tensile strength of metallic materials are shown. The alloys mentioned above have both a high damping factor, greater than 10%, or even 30%, and a high tensile strength, greater than 100, or even 600 MPa.

The embodiments shown relate to damping parts. However, it is possible to obtain damping with other parts of the bearing.

More generally, according to the invention, at least part of the bearing is made of an elastic metallic material with high damping capability, the damping factor of which is greater than 10%, preferably greater than 30%.

In a second embodiment, not shown in the figures, the part made of metallic material is one of the cages of the ball bearing. In a variant, the two cages are formed from this metallic damping material. The geometry of the bearing must be adapted to avoid stresses and contact pressures.

In a third embodiment, not shown in the figures, said moving parts are balls made of a metallic material with high damping power. Materials of nitinol type are particularly suitable for making such beads.

The invention also relates to a timepiece movement 10comporting at least one bearing 1tel as described above.

Claims (11)

1. Mechanical clockwork bearing (1) intended to be fitted on a mechanical movement (10) of a timepiece, the bearing (1) comprising, coaxial about a common axis of rotation (D), at least one internal cage (4, 14) and at least one external cage (5, 15) forming a circulation track (20), as well as a plurality of mobiles (12, 13) sliding or rolling in the circulation track (20) , during a relative movement between said inner cage (4, 14) and said outer cage (5, 15) which guide them and of which at least one of said inner cage (4, 14) and outer cage (5, 15) ) is a dynamic cage, characterized in that at least part of the bearing (1) is made of an elastic metallic material with high damping capability, the damping factor of which is greater than 10%, preferably greater than 30%. 2. Mechanical bearing (1) according to claim 1, characterized in that the metallic material has a tensile strength greater than 100 MPa, preferably greater than 400 MPa, or even 600 MPa. 3. Mechanical bearing (1) according to claim 1 or 2, characterized in that the material is to be chosen from the following list: -an alloy of at least 80% manganese and copper, an alloy of at least 80% copper, preferably 82%, aluminum and nickel, preferably 12% and 5%, an alloy of at least 80% iron, preferably 85%, chromium and aluminum, preferably 12% and 3%, an alloy of at least 60% iron, preferably 65%, and cobalt, preferably 35%, an alloy of at least 90% iron, preferably 95%, aluminum and carbon, preferably 6% and 0.2%, an alloy of at least 70% manganese, preferably 73%, copper, nickel and iron, preferably 20%, 5% and 2%, and an alloy of nitinol type comprising nickel at least 50%, preferably 55% and titanium, preferably 45%. 4. Mechanical bearing (1) according to any one of the preceding claims, characterized in that the bearing comprises a first damping part (6) intended to be positioned between one of said cages (4, 5, 14 , 15) and a bridge (3) of the automatic winding system of the movement (10), the first damping part (17) forming the part of the bearing made of an elastic metallic material with high damping capability. 5. Mechanical bearing (1) according to any one of the preceding claims, characterized in that the bearing (1) comprises a second damping part (17) intended to be positioned between one of said cages (4, 5, 14, 15) and means for maintaining the bearing on the movement (10), such as a nut (9) or a screw (7), the second damping part (17) forming the part of the bearing (1) made of an elastic metallic material with high damping capability. 6. Mechanical bearing (1) according to claim 4 or 5, characterized in that the first (6) and / or the second part (17) are washers. 7. Mechanical bearing (1) according to claim 4 or 5, characterized in that the first and / or the second part are tubes (22). 8. Mechanical bearing (1) according to one of the preceding claims, characterized in that the outer cage (5, 15) is made of the damping material. 9. Mechanical bearing (1) according to one of the preceding claims, characterized in that the internal cage (4, 14) is made of the damping material. 10. Mechanical bearing (1) according to one of the preceding claims, characterized in that said moving parts (12, 13) are balls made of a metallic material with high damping power. 11. Timepiece movement (10) comprising at least one bearing (1) according to any one of the preceding claims.