EP2413202B1 - Method for improving the wear and impact resistance of an horological component. Anchor for clock movement with wear and impact resistance - Google Patents

Description

Field of the invention

The invention relates to an anchor for a watch movement escapement mechanism, comprising at least one fork defining a fork entry which comprises horns arranged to cooperate with a rocker at an internal contact surface.

The invention also relates to an escape mechanism comprising such an anchor.

The invention also relates to a timepiece comprising at least one such anchor, and / or such an exhaust mechanism.

Background of the invention

The invention relates to the field of watch mechanisms, and more particularly the field of escape mechanisms.

In such a mechanism, the anchor cooperates, on the one hand with a balance, and on the other hand with an escape wheel. On one side or the other, an anchor works on shocks, on the one hand at the level of its fork, with horns, which cooperate with the balance plate pin and with the plateau ellipse, and of on the other hand at the level of pallets which cooperate periodically with the escape wheel. These incessant shocks are generators of wear, and therefore of degradation of the properties of the movement over time. In particular, in an exhaust mechanism, the wear of the fork inlets results in a decrease in the overall efficiency of the exhaust, and in the amplitude drop. The problem is therefore to reduce the wear of the escapement mechanism, in particular the anchor, and to make elastic the contact zone between the anchor and the balance, respecting a certain bulk imposed by the mechanism.

Few documents mention the wear problem. The rare solutions proposed offer surface coatings, particular choices of materials, the use of bearings, or the reduction of inertia by short lever arms. The choice of particular materials or surface coatings does not mitigate shocks, but delays their effects. The use of bearings does not fit well with a permanently impacted system, and the service life of bearings on such mechanisms is generally reduced, which is incompatible with a timepiece. The reduction of the inertia is more interesting, but it is difficult to intervene on an existing movement, and to modify its kinematics.

It should be noted, in this regard, that another way of reducing inertia is known, by the use of silicon components or the like, by the patent document. EP 0 732 635 AMSC.

Some patent documents relate to mechanical strength, which is the problem closest to that of the invention.

A patent is thus known US 2,717,488 , on behalf of La Générale Horlogère, relating to an exhaust with reduced noise level, comprising a radial notch escapement wheel for damping the shocks associated with the impacts of the teeth of the escape wheel on the pallets of the anchor, each tooth can, again, because of the flexibility provided by the notch, rely on the adjacent tooth, which gives the wheel, at the same time as the required flexibility, a certain robustness. The notches are necessarily large enough to allow the flexibility of the entirety of each tooth, relative to an attachment zone with respect to which the notch actually provides each tooth with a degree of freedom in pivoting. This provision is not applicable to many components, a pivotal mobility is not compatible with their kinematic operation.

The patent document is still known EP 1 870 784 in the name of OMEGA, which describes a serrated wheel with teeth, and proposes a solution to prevent these teeth from being damaged by shocks. The wheel according to this patent comprises flexible and curved arms, these arms bending tangentially, with a decreasing width towards the periphery of the wheel. These arms each have an end tooth, which is also flexible. If such a wheel may be suitable for an escape wheel, its arrangement is less suitable, in the same way as for the previous patent document, the particular kinematics related to certain components such as anchors. Furthermore, the equipment of an escape mechanism by such an escape wheel involves the replacement of the original wheel by this special wheel, without the possibility of reuse of the previous one.

Various documents propose mechanisms intended to reduce the functional play at the gear level, or to reduce the effect of impacts or impulses on certain components. We thus know the document EP 1 555 584 A1 in the name of ROLEX SA, which describes a toothed mobile with catch-up teeth game having slots arranged at these teeth, which are combined with abutment means to limit the range of motion allowed by these slots, depending on the gear set to catch. The document JP 63 130961 A in the name of KIYOUIKU HAGURAMA KOGYO KK, similarly described teeth whose elasticity is provided by slots or chambers. The document EP 1 380 772 A1 on behalf of WIEDERRECHT still proposes such a gear. The document EP 1 983 389 A1 in the name of ETA SA has an exhaust mechanism including a balance plate has slots in the vicinity of impulse vanes arranged to cooperate with the exhaust wheels. The document US 443,363 A in the name of HANSEN describes an exhaust mechanism comprising elastic damping means. The document WO 2010/063393 A1 in the name of ROLLS ROYCE PLC still describes a toothing with teeth made flexible by the presence of slots connected to chambers.

In these embodiments, the stroke, inherent to the flexibility of the arms, evaluated at the level of the teeth is of the order of a few hundredths to a few tenths of a millimeter, which may prove to be too important in certain mechanisms.

Summary of the invention

The object of the present invention is to overcome all or part of the disadvantages mentioned above. To solve the particular problem of the wear of the anchor, the invention has sought to make elastic the contact area between the anchor and the balance, while respecting a certain size.

For this purpose, the invention relates to an anchor for a clockwork escapement mechanism, in a first variant, according to claim 1.

The invention also relates to an anchor for a clockwork escapement mechanism, in a second variant, according to claim 2.

The invention also relates to an escape mechanism comprising such an anchor.

The invention also relates to a timepiece comprising at least one such escape mechanism.

Brief description of the designs

• la figure 1 représente, de façon schématisée, partielle, et en perspective, une ancre d'horlogerie selon l'invention, dans une première variante de réalisation;
• la figure 2 représente, de façon schématisée, partielle, et en perspective, une ancre d'horlogerie à laquelle a été appliquée le procédé selon l'invention, dans une deuxième variante de réalisation;
• la figure 3 représente, de façon schématisée, partielle, et en perspective, une ancre d'horlogerie à laquelle a été appliquée le procédé selon l'invention, dans une troisième variante de réalisation;
• la figure 4 représente, de façon schématisée, partielle, et en section selon un plan médian d'entrée de fourchette, l'ancre de la figure 1, vue selon une direction A ;
• la figure 5 représente, de façon schématisée, partielle, et en vue de bout, l'ancre de la figure 2, vue selon une direction B ;
• la figure 6 représente, de façon schématisée, partielle, et en vue de face, une ancre d'horlogerie à laquelle a été appliquée le procédé selon l'invention, dans une quatrième variante de réalisation;
• la figure 7 représente, de façon schématisée, partielle, et en vue de face, une ancre d'horlogerie à laquelle a été appliquée le procédé selon l'invention, dans une cinquième variante de réalisation;
• la figure 8 représente, de façon schématisée, partielle, et en section selon un plan CC perpendiculaire au plan de fourchette, l'ancre de la figure 7 ;
• la figure 9 représente, de façon schématisée, partielle et en vue de face, un détail de la déformation d'une lèvre élastique réalisée selon l'invention ;
• la figure 10 représente, de façon schématisée, l'évolution de la déformation d'une telle lèvre élastique.

Other particularities and advantages will emerge clearly from the description which is given hereinafter, by way of indication and in no way limiting, with reference to the appended drawings, in which:

• the figure 1 represents, schematically, partially, and in perspective, a clock anchor according to the invention, in a first embodiment;
• the figure 2 represents, schematically, partially, and in perspective, a clock anchor to which the method according to the invention has been applied, in a second variant embodiment;
• the figure 3 represents, schematically, partially, and in perspective, a watch anchor to which the method according to the invention has been applied, in a third variant embodiment;
• the figure 4 represents, schematically, partially, and in section along a median plane of entry of fork, the anchor of the figure 1 seen in a direction A;
• the figure 5 represents, in a schematic, partial and end-to-end view, the anchor of the figure 2 , seen in a direction B;
• the figure 6 represents, schematically, partially, and in front view, a watch anchor to which the method according to the invention has been applied, in a fourth variant embodiment;
• the figure 7 represents, schematically, partially, and in front view, a clock anchor to which the method according to the invention has been applied, in a fifth variant embodiment;
• the figure 8 represents, schematically, partially, and in section on a plane CC perpendicular to the plane of fork, the anchor of the figure 7 ;
• the figure 9 represents, schematically, partially and in front view, a detail of the deformation of an elastic lip made according to the invention;
• the figure 10 represents, schematically, the evolution of the deformation of such an elastic lip.

Detailed Description of the Preferred Embodiments

The invention relates to an anchor for a watch movement escapement mechanism, comprising at least one fork defining a fork entry which comprises horns arranged to cooperate with a rocker at an internal contact surface.

The term horn is chosen to simplify the presentation. If, in general, the components which are preferred to apply the invention are salient, they may equally well include reentrant surfaces, and the invention applies in the same way.

According to the invention, flexibility is provided to this end horn by arranging it by making at least one slot or a micrometer chamber in the vicinity of the contact surface or the contact surfaces as the case may be, to delimit at least one elastic lip extending between this contact surface and this at least one slot or chamber, as visible on the Figures 1, 2, 3, 6, and 7 .

According to one characteristic of the invention, said at least one elastic lip is made comprising, on one of its external surfaces, at least one said contact surface.

The invention can be implemented both for the manufacture of new components, as part of an improvement of existing components. However, as will be seen in the following description, some embodiments are reserved for new confections. This is particularly the case when one chooses to make the clock component in a micro-machinable material according to the MEMS technologies or according to the "LIGA" method, which is particularly suitable for the implementation of the invention.

In the remainder of the description, reference will be made indifferently to the production of components, it should therefore be understood that it may be a question of both making new clothes or improving a component or a movement.

In a particular embodiment of the invention, this slot or chamber is made so as to define this elastic lip between this contact surface, this slot or chamber, and at least one other peripheral surface of the horn.

In a preferred but nonlimiting manner, this lip, and therefore this slot or chamber, is produced substantially perpendicularly or perpendicularly to a plane along which the component develops, this plane being itself orthogonal to the contact surface or contact surfaces as appropriate.

Preferably, at least one slot emerging at the level of lateral surfaces that the horn comprises parallel to this plane, is carried out by wire electro-erosion, or by laser, or, when one chooses to manufacture said component made of micro material -usable by MEMS technology or according to the "LIGA" process, this slot is made during the manufacture of the component during its manufacture according to MEMS technologies or according to the "LIGA" method.

In one embodiment where it is chosen to give flexibility to the horn by making at least one chamber, the latter is made in the thickness of the horn, without access to any of the external surfaces. of the latter, during the manufacture of said component in micro-machinable material according to MEMS technologies or according to the "LIGA" method. The making of such chambers is also possible with more traditional materials such as steel or alloys, but then involves a more expensive multi-layer realization.

It is necessary to give flexibility to the horn, without weakening it and degrading its mechanical resistance. It should avoid any plastic deformation, irreversible. In particular, it is necessary that the flexibility does not result in large amplitude oscillations around an attachment zone, which would sooner or later lead to fatigue phenomena in the metallurgical sense, and a risk of breaking the lip. elastic, even the horn itself. It is therefore preferable that the width, that is to say the smallest dimension of the slot or the chamber, be very small, so as to provide the flexibility of the elastic lip, but without allowing a movement detrimental to the held in time.

The Figures 9 and 10 schematize the deformation of an elastic lip 20 arranged at a horn 3 of an anchor 1, in the vicinity of a slot 5. An impact force F is applied at a contact surface S. last is at a distance L1 from the embedding point A of the elastic lip 5, which has a total length L2. The slot 5 has a width E1, and the lip 20 has a thickness E2. The deformation of the elastic lip 5 follows a function D = B (y) which is a function of the material, and values of F, L2, and E2.

According to the invention, it is ensured that the deformation of the lip 20, over its entire length AB, is L2, remains in the elastic domain, this deformation dependent on the material, F, E2, and L1 or L2.

It is further ensured that for the maximum permissible value Fm of F, and for the maximum value of y, namely L2, D is less than E1, namely that there is no contact between the elastic lip 20 and the rest of the horn 3.

In an exemplary embodiment of an anchor 1 of S15P steel of 210 GPa elastic limit, with an impact force F of 80 mN, for dimensions E1 = 15 microns, E2 = 30 microns, and L2 = 150 μm, we obtain a maximum value of D equal to 2 μm, and a stress level of less than 800 MPa.

Preferably, it is made to limit the smallest dimension of the elastic lip, to give it sufficient flexibility.

In short, it must be ensured that the deformations of the elastic lip remain in the elastic range of the material that constitutes it. Its width E2 is an important parameter of its dimensioning, because it must be ensured that the combination of the impact force F and the dimensions of the elastic lip causes deformations of the lip in its elastic domain.

Preferably, the width E2 of the elastic lip is less than a quarter of its length L2, and preferably less than one-eighth of L2. In a preferred application, this width E2 is, again, less than or equal to 30 μm.

The smallest dimension of the slot E1 must be just large enough to prevent contact of the point B of the lip with the other part of the horn 3.

For this purpose, advantageously this slot or chamber is made with a smaller dimension of a few micrometers, in a ratio of less than one eighth with respect to its development in length.

Preferably, it is arranged to also limit the smallest dimension of the elastic lip, to give it sufficient flexibility.

The invention is particularly applicable to the components of an escape mechanism, which are the most frequently solicited by constraints related to pulses and shocks.

In particular, the nonlimiting application of the invention to an anchor is particularly advantageous.

The invention thus relates to an anchor 1 for a watch movement escapement mechanism, comprising at least one fork defining a fork inlet 2. This fork inlet 2 comprises horns 3 and 4 arranged to cooperate at the level of surfaces. S contact, with a rocker, which is not shown in the figures, usually at a plateau pin that includes the pendulum.

According to the invention, the fork inlet 2 comprises, at the level of at least one horn 3, 4, and preferably at the level of each horn 3, 4, at least one slot, respectively 5, 6, and / or at least one chamber 30, for delimiting at least one elastic lip 20, 21, extending between a contact surface S, and this slot 5, 6 or chamber 30.

Each slot 5, 6, or chamber 30, is arranged to provide the corresponding horn with an elasticity, which makes it possible to soften the shock during each pulse, absorbing part of the impact energy, then restoring it subsequently. to this impact. Thus the slot or the chamber makes it possible to make the contact zone elastic. The function of the slot or chamber is to reduce wear by softening the contacts between the tray ellipse or the ankle balance plate and fork of the anchor, during the phases of release and impulse.

Another object achieved by the invention is to reduce the phenomenon of adhesion to the exhaust.

Each slot or room is in straight or any profile. A room here will be called a volume enclosed in the material and not opening, and will be called slot a space opening on at least one of the outer surfaces of the component concerned.

The width of each slot is preferably a few micrometers, and is always very small relative to its development in length, in a ratio preferably of less than one-eighth.

Preferably, each slot extends in at least one oblique direction relative to a plane P in which the fork inlet 2 develops, or even the entire anchor 1 as is generally the case. In a preferred and economical manner, each slot extends perpendicularly to this plane P. Thus an elaboration of the anchor 1 according to the MEMS technologies, or according to the "LIGA" method or the like, is it particularly easy. For other embodiments of the anchor 1, in particular from a metal sheet, or plastic, or polymer, or other, the manufacture of a slot perpendicular to the plane P is preferable because it can be made by wire EDM, or wire cutting, laser, plastic injection, or the like.

The anchor 1 can also be made of a more conventional material: uncured steel "S15 P", lead-free steel "Ck75", aluminum alloy, other metal or alloy. The treatment for manufacturing the board from which the anchor is taken is of particular importance, and is well known to those skilled in the art. As regards plastics, a polymer such as POM "Hostaform" can be used.

A component according to the invention may, in such a material, be produced by laser technology, with a through etching, wire electro-erosion, water jet cutting, or the like.

In a preferred embodiment, each slot opens at the peripheral contour of the fork inlet 2, that is to say, as the case may be, towards the inside of the horns, that is to say on the the balance plate pin, at an internal surface, respectively 7, 8, or towards the outside of the horns, that is to say on the opposite side to the plateau pin, at an outer surface, respectively 9, 10.

A first embodiment variant is represented on the figure 1 . The fork inlet 2 comprises, at the level of at least one horn, and preferably at the level of each horn, a slot 5, 6, which extends perpendicularly to the plane of the anchor, and opens towards the inside. horns, that is to say the fork entry 2 on the side of the balance plate pin, at an inner surface 7, 8, delimiting at least one elastic lip 20, 21, s' extending between this inner surface 7, 8, and this slot 5, 6.

A second variant embodiment is represented on the figure 2 . The fork inlet comprises, at the level of at least one horn, and preferably at the level of each horn, a slot which extends perpendicular to the plane of the anchor, and opens outwards, that is, that is to say on the opposite side to the pendulum plate peg. The slot 5, 6 opens at the peripheral contour of the fork inlet 2 towards the outside of the horns, at an outer surface 9, 10, delimiting at least one elastic lip 20, 21 extending between this outer surface 9, 10, and this slot 5, 6. This arrangement also reduces the intensity of the impacts with the reversal stops.

A particular advantage of this arrangement is to limit the over-stresses, in case of impact of the ellipse on the top of the horn, and to limit the risk of breakage, for example breakage of the pendulum pivot.

A third variant embodiment, as visible on the figure 3 , combines the embodiments of the first mode and the second mode, with on each horn a slot opening on an inner end surface and a slot opening on an outer end surface. each horn 3, 4 has a slot 5, 6 opening on an inner surface 7, 8, and a slot 5A, 6A opening on an outer surface 9, 10, delimiting a plurality of elastic lips 20, 20A, 20B, 21, 21A, 21B, extending between the periphery of the horn 3, 4, the inner surface 7, 8, the outer surface 9, 10, and the slots 5, 5A, 6, 6A.

A fourth embodiment variant is represented on the figure 6 , in which the elastic slit 5, 6, is not open on an internal end surface 7, 8, or outer 9, 10, but only on at least one of the side faces 16, 17, that includes the anchor 1, parallel to the plane P of the latter. Preferably, for a symmetry of the internal stresses, the slot opens on the two opposite lateral faces.

A fifth embodiment variant is shown on the Figures 7 and 8 : it comprises at least one chamber 30 inside a horn, this chamber 30 is not open, and is delimited preferably on the side of the inner end surface 7 and the outer end surface 9, by outer zones of small section 12, 13, so that the end of the horn has an elastic behavior. Preferably and for the same purpose, the chamber 30 is also delimited, on the side of each of the lateral surfaces 16, 17, of the anchor 1, by a lateral zone of small section, 14, 15. The production of an anchor 1, according to the fifth mode, is possible by development in a micro-machinable material according to MEMS technologies, or according to the "LIGA" method or the like, and is particularly easy.

In this respect, the choice of such a micro-machinable material makes it possible, precisely, to make slits or very thin chambers, without having to fear the existence of a local defect in material, a pre-crack, or local over-stresses, which can be more met with a more traditional steel or alloy. The very small dimensioning of the slot or chamber in its smaller dimension limits the amplitude of vibration of the elastic lips, prevents any non-reversible deformation, and prevents any breakage of these lips.

It is naturally possible to produce an elastic lip component according to the invention in another material, steel or other alloy, with advantageously a layer deposited on the surface of this component, or a heat treatment and / or surface of this component .

In an alternative embodiment, the slot or chamber is not filled with air or vacuum, but with another material with different characteristics of the base material, for example an adhesive, or a surface treatment or coating. flexible and thick of the order of 5 to 10 microns. This other material may have particular elastic characteristics, which makes it possible to adapt a particular elastic behavior, and to participate in the damping and the anti-wear action. The fact of having a solid component makes it possible to avoid the accumulation of wear waste from the clockwork movement in the slots, which moreover constitutes the advantage of being made with a non-opening chamber.

Similarly, it is possible to insert in the slot or chamber a deformable plastic.

It is understood that the figures represent only a slot or a chamber in each embodiment, but it is naturally possible to juxtapose a plurality of slots or / and chambers, as well as to varieg the various modes exposed, non-limiting of the invention.

For example, a plurality of slots or substantially parallel chambers, shaped chevron, allows, even if they are very small, including a small development in their largest dimension, to give the horn sufficient flexibility.

The entire anchor horn is thus made flexible by at least one such slot or chamber, to reduce wear, making elastic the contact zone with the balance.

Naturally what applies to one horn applies to the other, preferably symmetrically with respect to a median plane P 'orthogonal to the plane P.

A particular embodiment is made with an anchor 1 made of silicon, or a silicon compound.

The invention also relates to an escape mechanism comprising at least one such anchor.

The invention also relates to a timepiece comprising at least one such anchor, and / or such an escape mechanism, and / or at least one component made or improved according to this method.

Of course, the present invention is not limited to the illustrated example but is susceptible of various variations and modifications that will occur to those skilled in the art.

Claims (12)

1. Escapement lever (1) for an escapement mechanism of a timepiece movement, including at least one fork delimiting a fork notch (2) which includes horns (3; 4) each arranged to cooperate with a balance impulse pin on an inner contact surface (S), characterized in that said fork notch (2) includes, in at least one said horn (3; 4), a slot (5; 6) and/or a chamber (30), to delimit at least one elastic lip (20; 21) extending between said first contact surface (S) and said slot (5; 6) or chamber (30), said inner contact surface (S) being located on an inner surface (7; 8) comprised in said elastic lip (20; 21) inside said fork notch (2), and on the opposite side to said slot (5; 6) and/or to said chamber (30), said slot (5; 6) or chamber (30) being arranged to confer elasticity on said corresponding horn (3; 4), which softens the shock on each impulse by absorbing part of the impact energy and then returning said energy subsequent to said impact.
2. Escapement lever (1) for an escapement mechanism of a timepiece movement comprising at least one fork delimiting a fork notch (2) which includes horns (3; 4) each arranged to cooperate with a balance impulse pin on an inner contact surface (S), characterized in that said fork notch (2) includes, in at least one said horn (3; 4), a slot (5; 6) which opens at the peripheral contour of said fork notch (2) towards the exterior of said horn (3; 4), on an outer surface (9; 10) of said horn (3; 4) located on the opposite side to said inner contact surface (S), delimiting at least one elastic lip (20, 21) extending between said outer surface (9; 10) and said slot (5; 6), said elastic lip (20, 21) including, on one of said outer surfaces, at least one outer contact surface which is arranged to cooperate with banking members of the escapement mechanism when comprised therein, and to reduce the intensity of impacts with said banking members.
3. Escapement lever (1) according to claim 1, characterized in that said at least one slot (5; 6) or/and chamber (30) is substantially perpendicular to a plane (P) in which said escapement lever (1) develops, said plane (P) being in turn orthogonal to said inner contact surfaces (S).
4. Escapement lever (1) according to claim 1 or 3, characterized in that said at least one slot (5; 6) opens at lateral surfaces comprised in said horn (3, 4) parallel to a plane (P) in which said escapement lever (1) develops, said plane (P) being in turn orthogonal to said inner contact surfaces (S).
5. Escapement lever (1) according to any of claims 1 to 4, characterized in that the width (E2) of said elastic lip (20, 21) is less than one quarter of the length (L2) thereof, and is less than or equal to 30 µm.
6. Escapement lever (1) according to claim 1 or any claims dependent thereon, characterized in that each said horn (3; 4) includes an inner slot (5; 6) opening on a said inner surface (7; 8) and an outer slot (5A; 6A) opening on an outer surface (9; 10), delimiting a plurality of elastic lips (20; 20A; 20B; 21; 21A; 21B) extending between the periphery of said horn (3; 4), said inner surface (7; 8), said outer surface (9; 10) and said slots (5; 5A; 6; 6A).
7. Escapement lever (1) according to claim 1 or any claims dependent thereon, characterized in that said escapement lever (1) includes at least one said slot (5; 6) that does not open on a said inner surface (7; 8) or on an outer surface (9; 10) of said horn (3; 4), but only on at least one of the lateral faces (16; 17) comprised in said escapement lever (1), parallel to the plane (P) of the latter.
8. Escapement lever (1) according to claim 1 or any claims dependent thereon, characterized in that said escapement lever (1) includes said at least one chamber (30) comprised in the thickness of said horn (3, 4), without access on any of the outer surfaces of the latter.
9. Escapement lever (1) according to claim 8, characterized in that said escapement lever (1) includes at least one said chamber (30), inside a said horn (3; 4), and which is delimited on the side of one said inner surface (7; 8) and one outer surface (9; 10) of said horn (3; 4) by elastic end lips (12; 13), such that the end of said horn (3; 4) has elastic behaviour.
10. Escapement lever (1) according to any of the preceding claims, characterized in that said escapement lever (1) is made of micro-machinable material.
11. Escapement mechanism including at least one escapement lever (1) according to any of claims 1 to 10.
12. Timepiece including at least one escapement mechanism according to claim 11.

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