EP3291027B1 - Membrane shock absorber - Google Patents

Description

The present invention relates to a shock absorber device for an axis of a mobile of a timepiece arranged on a support, said support being provided with an opening so that said axis can move in translation in said opening, said axis comprising, at each end, a tigeron cooperating with a pivoting element.

BACKGROUND TECHNOLOGY

In timepieces, there are shock absorbing or shockproof systems to protect the axes of mobiles. A first system is a lyre system that is to say that the plate or bridge is provided with a hole through which the shank of an axis can pass. This hole serves as a housing for a support, pierced at its center, in which a kitten is arranged. This kitten carries a pierced stone and a counter-pivot stone, the whole being put under stress by a lyre spring arranged between the support, which has flanges serving as points of support, and the kitten. Another system is the fall arrest system in which the pivots of the beam are made so as to give them the shape of a cone and hold them in place by a small cup of corresponding shape, mounted on a leaf spring.

Watchmaking shock absorbers are usually constituted by mechanical springs and are still sized according to the old rules, according to practical rules considered as the best compromise between mechanical stability during operation and resistance to mechanical deformations.

Licences CH335173 A and FR1140584 A disclose anti-shock bearings with tongue springs. The demand CH 705 905 A2 discloses a shockproof bearing diaphragm. The patent CH 702 314 B1 discloses a bearing provided with a spring arm which can be replaced by a membrane.

In particular, the sprung balance shock absorbers, the parachutes and the lyres are dimensioned so as not to be activated up to relatively large shock accelerations (between 200 and 500 times the gravity), thanks to the spring preload. Beyond this threshold value, the spring can be deformed and absorb some of the impact energy. However, because of low mechanical damping of the metal blades used as shockproof, most of the energy is restored to the pendulum. The local deformation of the pendulum pivot is therefore very likely, already for relatively small shocks. This deformation, which has a considerable impact on the chronometric accuracy of the watch, is generally neglected because the standard certifying the chronometric stability of a COSC watch after a shock of one meter is not severe (60 s / j of difference).

There is therefore a need in improving the chronometric stability of the watch after a shock.

SUMMARY OF THE INVENTION

The invention aims to overcome the disadvantages of the prior art by proposing to provide a shock absorbing system having a progressiveness in shock absorption while preventing the tigeron is exposed to the impact energy.

For this purpose, the present invention relates to a shock-absorbing device for an axis of a mobile of a timepiece according to claim 1.

The axis has a first diameter and comprises at each end an area of a second diameter from which the shank extends, the second diameter being smaller than the first diameter.

The transition between the first diameter zone and the second diameter zone is performed to form a shoulder.

The axis further comprises, in the zone having a second diameter, a first radially extending peripheral protruding portion, said projecting portion being spaced from the shoulder so that the diaphragm spring can be inserted into the space between said first projecting portion and said shoulder.

In one embodiment, the device further includes a second diaphragm spring disposed in the first aperture such that the first diaphragm spring and the second diaphragm spring are located on either side of said first protrusion.

In another embodiment, the axis further comprises a second protruding portion arranged so that the first protruding portion and the second protruding portion are located on either side of the second diaphragm spring.

In one embodiment, the thickness of said membrane or membrane spring is between 5 microns and 50 microns.

In another embodiment, the membrane spring or springs may be made of a material selected from the list comprising: silicon, crystalline silicon carbide, ceramic silicon carbide, silicon nitride and metallic glass.

In another embodiment, the membrane spring or springs may be made of a stretchable material of the polymer or elastomer resin type.

In another embodiment, the pivoting element is a fall arrest system.

In another embodiment the pivoting element is a kitten and lyre system.

BRIEF DESCRIPTION OF THE FIGURES

• Les figures 1 et 2 représentent une vue schématique de différentes formes ne faisant pas partie de l'invention;
• Les figures 3 et 4 représentent une vue schématique du fonctionnement d'un mode de réalisation ne faisant pas partie de l'invention;
• Les figures 5 et 6 représentent un schéma d'un mode de réalisation du dispositif selon l'invention;
• Les figures 7 et 8 représentent un schéma d'un autre mode de réalisation du dispositif selon l'invention et d'une de ses variantes.

The objects, advantages and features of the invention will appear more clearly in the following detailed description of at least one embodiment of the invention given solely by way of nonlimiting example and illustrated by the appended drawings in which:

• The Figures 1 and 2 represent a schematic view of different forms not forming part of the invention;
• The Figures 3 and 4 show a schematic view of the operation of an embodiment not forming part of the invention;
• The figures 5 and 6 represent a diagram of an embodiment of the device according to the invention;
• The Figures 7 and 8 represent a diagram of another embodiment of the device according to the invention and one of its variants.

DETAILED DESCRIPTION

The present invention proceeds from the general idea of providing a shock absorbing system having a progressiveness in shock absorption.

On the Figures 1 and 2 , a shock absorbing device 1 or shockproof system is shown. This shock absorbing device or shockproof system 1 is mounted in a base member 100 of a timepiece movement. In particular, the plate or the bridges of the movement are the basic element in which the shockproof system 1 according to the invention is placed. This shock absorbing device is used to dampen the impacts of an axis or shaft 200 of a timepiece mobile: a wheel or a balance wheel or an escape wheel.

This base element 100 is provided with an opening 102 opposite the axis 200 to be damped. The axis 200 cooperates with a pivot element 300 by the tigeron intermediate 201 arranged at each end of the axis 200. This pivot element 300 can be in several forms.

A first form is called a fall arrest device in which the pivots or tigeron 201 of the axis 200 of the mobile are made so as to give them the shape of a cone and hold them in place by a small cup 310 of corresponding shape mounted on a leaf spring 312 as visible at figure 1 . The spring blade 312 may be mounted on a support 314 fixed to the plate 100.

A second form consists of a pivot element kitten and lyre. Such an element comprises a kitten 324 placed in a housing 322 of a frame 320. In the kitten 324, a pierced stone 325 and a counter pivot stone 326 are inserted. The kitten is then retained in the housing of the frame via a spring 327 in the form of lyre deforming to absorb shocks as visible in the figure 2 .

The shock absorbing device further comprises one of the spring means 110 for damping the axis of the mobile.

These spring means 110, visible to the figure 2 , advantageously comprise at least one first diaphragm or diaphragm spring 112. Such a diaphragm spring 112 is arranged at the opening 102 of the base member 100 in which the axis 200 is inserted.

Such a diaphragm spring 112 is used to prevent the most energetic impact during a shock being suffered by the pivot / skewer 201 of the axis of the mobile and thus to find an innovative solution for absorbing and dissipating the most of the shock energy by the impact of another part of said axis.

As such, the diaphragm spring 112 according to the invention is arranged at the opening 102 of the base member 101. This membrane comprises a hole 113 through which the axis takes place. The membrane 112 is designed to cooperate with the axis and, more particularly, with a shoulder 202 of said axis. Indeed, the axis 200 of the watch mobile comprises at each end a tiger 201 for its pivoting. Depending on the diameter of said axis 200, it is not necessarily wise to have an end directly provided with a tungsten 201. As a result, the axis 200 may be designed so as to have a main portion having a first diameter D1 and at the ends, a portion of a second diameter D2 smaller than the diameter of the main portion. Such narrowing may be linear or abrupt to form a shoulder 202.

During normal operation (in the absence of shock), there is no contact between the membrane and the axis of the watch mobile as visible in the figure 3 .

During a shock having an axial contribution as visible in the figure 4 the axis 200 moves and arms the traditional anti-shock 300 (lyre or parechute) but, after a relatively short axial stroke (in the Z direction), the axis 200, via its shoulder 202, abuts against the membrane 112 'with a liner'. The movement of the axis 200 of the mobile thus begins to deform the membrane 112 which absorbs a considerable part of the impact energy by its deformation in extension (in the case of a stretch membrane) and / or flexion, in the case a standard thin elastic membrane. Therefore, the tigeron 201 is no longer the part of the axis that stores the maximum energy. The risks of rupture of the tigeron 201 are therefore reduced.

The thickness of the membrane 112 is advantageously between 5 microns and 50 microns (depending on the material used) and the membrane 112 may be made of silicon, silicon carbide (crystalline or ceramic), silicon nitride (in these three cases it can be manufactured by DRIE technology) or metal glass.

In a particularly advantageous variant, the membrane 112 may be made of a stretching material with a large energy dissipation such as, for example, elastomeric polymers or resins (especially silicone, but also PVC, PVDC, PE ...). In this case, the elastic properties in the direction of deformation Z, will depend on the elongation applied in the XY plane, which is advantageously between 2% and 15% of the dimension of the membrane in the same direction of the elongation.

The opening 113 of the diaphragm 112 (within which the balance shaft is located) may be of circular, square, rectangular or polygonal geometry. The membrane 112 may also not be completely closed around the axis of the mobile. The dimension of the opening 113 is such that the projection of the membrane in the XY plane is partially superimposed on the projection of the axis 200 of the moving body in the same plane, the superposition being ensured by one or more portions of the axis. extending over a diameter substantially greater than the diameter of the tigeron at the end of the axis dedicated to pivoting. This is either a linear shrinkage or at least one shoulder.

In a second embodiment visible at the figure 5 , the shaft 200 is made to have several shoulders and the membrane 112 is activated regardless of the direction of impact. Such an embodiment consists of having a first shoulder 202a to make a transition between two zones of different diameters, the diameter being reduced towards the end. The second shoulder 202b consists in providing, at the region of smaller diameter, a radially extending peripheral portion 203 protruding. The two shoulders 202a, 202b are then arranged so that a space 204 exists between them. This space 204 is used for the membrane 112 to be placed there. Therefore, regardless of the axial displacement of the shaft 200 of the mobile following an impact, at least one membrane 112 will be biased to dissipate the energy of said shock.

In the presence of two membranes 112, positioned at each end of the shaft 200 of the mobile, the absorption of the impact energy is maximized since during an impact, the two membranes will be solicited as visible at the figure 6 .

In a third embodiment visible at the figure 7 , it is expected to have several membranes 112 for each end. In one embodiment with first and second membranes 112 for each end, the mobile shaft is designed similarly to that of the second embodiment. Such a shaft 200 of mobile is to have a first shoulder 202a to make a transition between two zones of different diameters, the diameter being reduced in approximates the end. The second shoulder 202b consists in providing, at the region of smaller diameter, a radially extending peripheral protrusion. The two shoulders 202a, 202b are then arranged so that a space exists between them. This space is used so that a first membrane can be placed there. The second membrane 112 is then placed on the other side of the protruding portion 203 so that the two membranes 112 are placed on either side of the projecting portion.

Thus, in the case of a shock pushing the tigeron to exert a stress on the conventional anti-shock system, the displacement of the axis of the moving means causes a contact between the first shoulder and the first membrane and between the projecting portion and the second membrane 112. These two membranes 112 then deform to dissipate the energy of the shock, the latter being distributed over the two membranes.

On the other hand, in the case of an impact pushing the tigeron to move away from the conventional anti-shock system, the displacement of the axis of the mobile causes a contact between the protruding part and the first membrane. It will of course be possible to provide several projecting parts 205 as visible in FIG. figure 8 and other membranes. The absorbed energy can be maximized and the apparent rigidity 'seen' by the balance during the shock can be increased depending on the energy of the shock.

It will be understood that various modifications and / or improvements obvious to those skilled in the art can be made to different Embodiments of the invention described in the present description without departing from the scope of the invention.

Claims (8)

1. Shock absorber device (1) for a staff (200) of a wheel set of a timepiece arranged on a support (100), said support being provided with an opening (102) in order for said staff to be able to move in translation inside said opening, said staff comprising, at each end, a pivot-shank engaging with a pivoting element (300), said device further comprising at least one first resilient membrane spring (112) arranged inside the first opening, said first membrane being pierced with a through-hole (113) through which said staff passes, said staff comprising at least one part having a diameter (D1) of greater than that of the through-hole of said first membrane so as to act as a banking for said staff during a movement following a shock, the staff (200) having a first diameter (D1) and comprises, at each end, an area having a second diameter (D2) from which the pivot-shank extends, the second diameter being smaller than the first diameter, the transition between the area of the first diameter (D1) and the area having a second diameter (D2) being produced such that it forms a shoulder (202), characterised in that the staff (200) further includes, in the area having a second diameter (D2), a first peripheral protruding part (203) extending radially, said protruding part being spaced apart from the shoulder (202) so that the membrane spring (112) can be inserted into the space (204) between said first protruding part and said shoulder.
2. Shock absorber device according to claim 1, characterised in that it further includes a second membrane spring (112) arranged such that the first membrane spring and the second membrane spring are located on either side of said first protruding part (203).
3. Shock absorber device according to claim 2, characterised in that said staff further includes a second protruding part (205) arranged such that the first protruding part (203) and the second protruding part are located on either side of the second membrane spring (112).
4. Shock absorber device according to one of the preceding claims, characterised in that the thickness of the one or more membrane springs lies in the range 5 µm to 50 µm.
5. Shock absorber device according to one of the preceding claims, characterised in that the one or more membrane springs can be made of a material chosen from the list comprising: silicon, crystalline silicon carbide, ceramic silicon carbide, silicon nitride and metallic glass.
6. Shock absorber device according to one of claims 1 to 4, characterised in that the one or more membrane springs can be made of a stretchable material of the polymer or elastomer resin type.
7. Shock absorber device according to one of the preceding claims, characterised in that the pivoting element is a parachute system.
8. Shock absorber device according to one of claims 1 to 6, characterised in that the pivoting element is a setting and lyre system.

Images