EP3783445A1 - Timepiece regulator mechanism with high quality factor and with minimum lubrication - Google Patents

Abstract

Clockwork regulator (300), comprising a resonator mechanism (100) with virtual pivot, with flexible guidance, with a quality factor greater than 1000, the inertial element (2) of which cooperates indirectly with an escape mechanism (200 ) free in the operating cycle of which the resonator mechanism (100) has at least one phase of freedom where it is without contact with the escape mechanism (200), this regulating mechanism (300) comprises a pair of components (22; 32) comprising friction surfaces (20; 30) arranged to cooperate in contact with one another, where the first friction surface (20) is formed by the surface of an element comprising silicon carbide.

Description

Field of the invention

The invention relates to a clockwork regulating mechanism, comprising, arranged on a plate, a resonator mechanism with a quality factor Q, and an escape mechanism which is subjected to a torque of motor means that a movement comprises, said movement. resonator mechanism comprising an inertial element arranged to oscillate relative to said plate, said inertial element being subjected to the action of elastic return means fixed directly or indirectly to said plate, and said inertial element being arranged to cooperate indirectly with a mobile d 'exhaust that comprises said exhaust mechanism, said regulating mechanism comprising at least a pair of components comprising a first component and a second component comprising respectively a first friction surface and a second friction surface which are arranged to cooperate in contact with the one with the other.

The invention also relates to a watch movement comprising such a regulating mechanism.

The invention also relates to a watch comprising such a movement and / or such a regulating mechanism.

The invention also relates to a method for producing such an escape mechanism.

The invention relates to the field of horological mechanisms comprising constantly moving components, and more particularly to the field of escapement mechanisms.

Background of the invention

Watch manufacturers have always endeavored to increase the reliability of movements, by reducing the frequency of maintenance, while ensuring the precise operation of watch movements.

The lubrication of moving parts and components is a difficult problem to solve. Long tribological experiments are necessary to develop solutions which make it possible to simplify or even eliminate lubrication.

More particularly, an operation without lubrication of the exhaust mechanisms is sought, by attempting to define couples of friction materials exhibiting a low and stable coefficient of friction as well as low wear, and exhibiting excellent resistance over time.

• l'entretien des va-et-vient d'au moins une masse inertielle, typiquement un balancier, que comporte le résonateur ;
• et le comptage de ces va-et-vient.

Many current mechanical watches are fitted with a sprung balance resonator, which constitutes the time base of the movement, and associated with an escapement mechanism generally with a Swiss anchor. This exhaust fulfills two main functions:

• maintenance of the back and forth movements of at least one inertial mass, typically a balance, which the resonator comprises;
• and counting these back and forth.

In addition to these two main functions, the escapement must be robust, resist shocks, and avoid jamming the movement (overturning). The Swiss lever escapement mechanism has a low energy efficiency (around 30%). This low efficiency results from the fact that the movements of the escapement are jerky, that there are drops or lost paths to accommodate machining errors, and also from the fact that several components transmit their movement to each other via inclined planes which rub against each other.

To constitute a mechanical resonator, at least one inertial element, one guide means and one elastic return means are needed. Traditionally, a spiral spring acts as an elastic return element for the inertial element that constitutes a balance.

When the inertial mass is guided in rotation by pivots which turn in plain ruby bearings, this gives rise to friction, and therefore to energy losses and operating disturbances, which depend on the positions of the watch in the 'space in relation to the field of gravity, and which one seeks to eliminate.

A new generation of mechanical resonators comprises, in connection with the inertial element, at least two flexible elements which perform the two functions of guiding in pivoting and of elastic return means. These new resonators allow higher oscillation frequencies, of the order of 10 Hz, or even 50 Hz or more, and much higher quality factors, often greater than 1000, and in particular of the order of 2000, than those of resonators traditional mechanics with balance and spring, generally of the order of 280. The energy to be supplied to the resonator at each half-wave is therefore much lower, for example 20 times lower.

The energy passing through the exhaust is therefore relatively much lower. This imposes a design of the exhaust components with reduced inertias. This characteristic is achieved, on the one hand by using materials of low density such as for example silicon, or the like, and on the other hand by reducing the size of the components of the escapement. Silicon (or one of its oxides, or even any other micro-machinable material now common in watchmaking) can advantageously be machined with one of the technologies derived from electronics such as "Deep Reactive Ion Etching" (DRIE) which allows precision. adapted to the operating constraints of such an exhaust. Silicon oxidizes naturally in air, but it can be oxidized during the manufacturing process to, for example, increase the toughness of components or change their thermoelastic coefficient. The controlled growth of silicon dioxide SiO ₂ makes it possible, in particular, to create prestressing in thin sections, and to create bistable or multistable components.

Silicon oxide (silica) is known for its propensity to adsorb water. This hygroscopic nature is also used to dry the air in certain packaging to prevent the goods transported there from being altered by humidity (for example in the form of silica-gel sachets).

In the case of mechanisms transmitting very weak energies, such as these new resonators, adhesion phenomena can occur. These surface phenomena can become predominant if the size of the components of the exhaust is small. These surface effects (friction and adhesion) in fact become more important than the volume effects (inertia, mass) as the size of the parts decreases. This ultimately results in potentially harmful sticking. The tests carried out have indeed shown a significant loss of efficiency when the relative humidity increases. Adhesion forces depend on different surface tensions and the volume of liquid, not on the force applied by one component on another. The influence of such sticking can lead to stopping of the movement when the escapement torque is low and the humidity is high, which risks causing loss of power reserve. In the absence of any particular precaution regarding contact surface, we can see, when a watch operates in an atmosphere with a humidity greater than 80%, phenomena of sudden drop in amplitude of the oscillator, even its stopping, and this all the more so as the energy the exhaust is weak; these phenomena can already occur with a lower humidity, of the order of 50%. Note that with low humidity, of the order of 20%, there is in principle no loss of amplitude or stopping.

It is in fact observed that the energy exchanged between such a new resonator and the escapement is very low, and is only slightly greater than the energy required to take off from the surfaces in contact and break a meniscus of lubricant. For example, the energy exchanged between the resonator mechanism and the escapement is of the order of three times to ten times the contact breaking energy. This circumstance naturally makes self-starting difficult after an unexpected stop, for example following a shock.

An alternative to remedy this problem consists in depositing a hydrophobic coating on the surface of the components made of micromachinable material (in particular made of silicon or / and silicon oxide). However, because of the operating constraints of the exhaust, this coating must be resistant to abrasion so as to guarantee long-term operation. The self-assembled monolayers or the film-forming lubricants which can be grafted on the surface may be insufficiently resistant, and reveal to wear the surface made of micromachinable material, in particular silicon and silicon oxide, again making the mechanism sensitive to humidity.

An epilame deposit has the disadvantage of aging over time, which is why it is important to look for materials with the least possible wear, for the contact surfaces of the friction components such as plate pin, stinger. , fork with horns, anchor pallet, escape wheel tooth, star, and the like.

Document XP002734688, “A study of static friction between silicon and silicon compounds”, by MM. Deng and Ko, describes the use in precision micro-mechanics of the silicon nitride - silicon pair, for low wear over time, and improved tribology.

Document XP002734924, “LPCVD against PECVD for micromechanical applications”, by MM, Stoffel, Kovacs, Kronast, Müller, describes the use of nitride of non-stoichiometric silicon, obtained by PECVD or LPCVD, to ensure tribological properties.

The document WO2009 / 049591 in the name of Damasko describes a process for manufacturing functional mechanical movement elements, in particular functional elements for making movement systems oscillate, the material or starting material of which is chosen from a group comprising a wide variety of compounds , including silicon nitride.

Summary of the invention

The invention proposes to provide a solution to the problem of the sticking of components with intermittent contact in a clockwork movement for a watch, comprising a new resonator with flexible guides and virtual pivot, with a quality factor greater than 1000, associated with a mechanism of 'exhaust.

The invention relates more particularly to the use of silicon carbide, or of derived materials essentially comprising silicon carbide, as a high performance tribological material in the exhaust.

To this end, the invention relates to a clockwork movement for a watch, comprising a new resonator with flexible guides and virtual pivot, with a quality factor greater than 1000, and an escapement mechanism, with improved tribology, according to claim 1.

The invention also relates to a method for producing such an escape mechanism, characterized in that each pair consisting of a first friction surface and a second opposing friction surface is produced, by producing a component in silicon carbide. with a substrate to constitute said first friction surface and / or the second friction surface, or else by sintering, or else by massive elaboration.

Brief description of the drawings

• la figure 1 représente, de façon schématisée et en vue en plan, un mécanisme d'échappement traditionnel comportant notamment une palette d'ancre coopérant en contact avec une roue d'échappement, au niveau de surfaces de contact agencées selon l'invention ;
• la figure 2 représente, de façon schématisée, la coopération entre les surfaces de contact antagonistes ;
• la figure 3 représente, de façon schématisée et en vue en plan, un mécanisme régulateur d'horlogerie, selon l'invention, comportant un mécanisme résonateur à guidages flexibles et pivot virtuel avec un haut facteur de qualité supérieur à 1000, comportant une masse inertielle oscillante porteuse d'une cheville de plateau agencée pour coopérer avec une fourchette d'une ancre laquelle est par ailleurs agencée pour coopérer avec les dents d'une roue d'échappement ;
• la figure 4 est un détail de la figure 3 ;
• la figure 5 représente, sous forme d'un schéma-blocs, une montre comportant un mouvement lequel comporte un tel mécanisme régulateur d'horlogerie, selon l'invention.

Other characteristics and advantages of the invention will become apparent on reading the detailed description which follows, with reference to the appended drawings, where:

• the figure 1 shows, schematically and in plan view, a traditional escape mechanism comprising in particular an anchor pallet cooperating in contact with an escape wheel, at the level of contact surfaces arranged according to the invention;
• the figure 2 represents, schematically, the cooperation between the antagonistic contact surfaces;
• the figure 3 shows, schematically and in plan view, a clockwork regulating mechanism, according to the invention, comprising a resonator mechanism with flexible guides and virtual pivot with a high quality factor greater than 1000, comprising an oscillating inertial mass carrying d a plate pin arranged to cooperate with a fork of an anchor which is furthermore arranged to cooperate with the teeth of an escape wheel;
• the figure 4 is a detail of the figure 3 ;
• the figure 5 represents, in the form of a block diagram, a watch comprising a movement which comprises such a clockwork regulating mechanism, according to the invention.

Detailed description of the preferred embodiments

The invention relates to the use of silicon carbide as a material allowing the operation with minimum lubrication of a clockwork regulating mechanism comprising a resonator mechanism with flexible guides and virtual pivot with a high quality factor greater than 1000, associated to an escape mechanism.

Operation without lubrication is a special case. But the characteristics set out below are also suitable for a lubricated regulator mechanism, the advantage of which is to be able to reach an amplitude greater than that of a regulator operating dry, with in particular a gain of 10% to 20% of amplitude in certain cases. The regulating mechanism 300 then preferably comprises a lubricant with a surface tension of less than 50 mN / m, and more particularly less than 40 mN / m, and more particularly still less than or equal to 36 mN / m; the surface tension of the watch lubricant used is then significantly lower than that of water, which is 72 mN / m, ie between approximately half and two thirds. The invention is more particularly described for dry operation, but those skilled in the art will have no difficulty in extrapolating it to a lubricated mechanism.

• ou bien par du carbure de silicium stoechiométrique SiC, qui peut être massif dans le cas le plus général, ou encore en couche mince ;
• ou bien selon une composition dite non stoechiométrique Si_xC_yH_z, avec x égal à 1, y compris entre 0.8 et 5.0, et z compris entre 0.00 et 0.70, et plus particulièrement entre 0.04 et 0.70, qui est de préférence appliqué en couche mince, mais qui peut aussi être constitutive d'un composant massif.

For convenience of language, a material which is made up of:

• or else by stoichiometric silicon carbide SiC, which can be solid in the most general case, or else in a thin layer;
• or else according to a so-called non-stoichiometric composition Si _x C _y H _z , with x equal to 1, including between 0.8 and 5.0, and z between 0.00 and 0.70, and more particularly between 0.04 and 0.70, which is preferably applied in a thin layer, but which can also constitute a solid component.

The term “solid” is used here for a component whose smallest dimension is greater than 0.10 mm, while a “thin layer” has its smallest dimension less than 10 micrometers, and preferably less than 1 micrometer. Of course, many watch components include areas the smallest dimension of which is less than 0.10 mm, such as arms or escape wheel teeth, or the like; the watch components used in the case in point of high quality factor resonators generally come from a wafer with a thickness greater than 0.10 mm, or from an assembly of several thinner wafers (wafer bonding) to produce a wafer resulting in thickness greater than 0.10 mm.

Indeed, the experiment makes it possible to establish that the friction of the silicon carbide against the silicon or the silicon oxide exhibits particularly desired properties in a watch mechanism, and most particularly in the case of an escapement mechanism.

Such a friction torque has a low coefficient of friction, less than 0.17, over a wide range of force - speed (1mN - 200mN and 1 cm / s - 10 cm / s).

The literature teaches that, for hard elastic materials, due to the increase in shear stress as a function of pressure, the coefficient of friction usually varies a law of type: µ = S / P + α, where: S : limit shear stress, P: Hertz pressure, α: constant value parameter.

The parameter S determines the dependence of the torque on the pressure, and is therefore particularly useful to take into account in the case of dry friction in the exhaust where the contact forces and pressures vary greatly, as well as in the case of dry friction in the exhaust. 'interface between the exhaust and the resonator.

In comparison with other friction couples, the silicon carbide / Si or silicon carbide / SiO ₂ couples have a low dependence of the friction coefficient as a function of the normal force applied. This results in a very low S parameter. This behavior is particularly useful in the escapement since the normal force varies greatly, typically from 0 to 200 mN during contact and impact. During loss of contact and contact, silicon carbide makes it possible to maintain a low coefficient of friction of less than 0.2, a value which is usually considered as the critical operating threshold of the escapement.

During detachment (separation of the tooth of the escape wheel on the one hand, and the lifting of the anchor on the other hand, for example), it is the adhesion forces that intervene. When dry, electrostatic forces, van der Waals, Hydrogen, and others act. In the case of contact with a liquid (or fluid) medium, it is the surface tension forces that oppose the separation and thus consume energy. In absolute terms, we cannot consider them as frictional forces. In the case of conventional spring balance regulating mechanisms, we tend to assimilate them to frictional forces because the adhesion forces are much weaker than those of friction, and are almost negligible compared to them. In the case of high quality factor regulators, they are of the same order of magnitude, and may even be preponderant in certain cases. The underlying mechanisms and strategies for reducing friction or adhesion are different, and may even prove to be antagonistic in certain configurations.

In addition, silicon carbide is resistant to wear, which guarantees good durability.

Comparative experimentation with contact components made of silicon or silicon oxide show that the use of surface silicon carbide makes it possible to reduce oscillator stops to nothing.

The invention thus relates to a clockwork regulator mechanism 300, comprising, arranged on a plate 1, a resonator mechanism 100 with virtual pivot and flexible guide, with a quality factor Q greater than 1000, and an escape mechanism. 200 which is subjected to a torque of motor means 400 which a movement 500 comprises, in particular for equipping a watch 1000.

For example, the regulator mechanism 300 illustrated in figures 3 and 4 has an exhaust power of the order of 0.7 microwatt, which is about twenty times lower than in the case of a traditional regulator.

The resonator mechanism 100 comprises at least one inertial element 2 arranged to oscillate relative to the plate 1. This inertial element 2 is subjected to the action of elastic return means 3 fixed directly or indirectly to the plate 1. And this inertial element 2 is arranged to cooperate indirectly with an escape mobile 4 which the escape mechanism 200 comprises.

The figures show, in a nonlimiting manner, a plate pin 6 integral with an inertial mass 2, and arranged to cooperate with an anchor 7, which in turn is arranged to cooperate with such an escape mobile 4 here constituted by an escape wheel.

This resonator mechanism 100 is here a rotary resonator with virtual pivot, around a main axis DP, with flexible guidance comprising at least two flexible blades 5, and comprising such a plate pin 6 integral with the inertial element 2.

The escape mechanism 200 comprises an anchor 7 pivoting about a secondary axis DS and comprising an anchor fork 8 arranged to cooperate with the plate pin 6. This escape mechanism 200 is a free escape mechanism, in the operating cycle of which the resonator mechanism 100 has at least one phase of freedom where the plate peg 6 is at a distance from the anchor fork 8.

This regulating mechanism 300 is a mechanism with improved tribology, based on the findings set out above, and is designed to minimize the phenomena of sticking between the surfaces of components with variable and / or discontinuous contact.

More particularly, this resonator 100 has a quality factor greater than 1000, more particularly greater than 1800, more particularly still greater than 2500.

The technology of virtual pivot resonators, and in particular flexible blades, does not yet allow large amplitudes of oscillation of the inertial mass. In the case of the invention, the oscillation amplitude of the resonator 100 is less than 180 °, more particularly less than 90 °, more particularly still less than 40 °.

The oscillation frequency of the resonator 100 is greater than 8 Hz, more particularly greater than or equal to 10 Hz, more particularly still greater than or equal to 15 Hz.

In a manner specific to the invention, this regulating mechanism 300 comprises, at the level of the resonator mechanism 100 and / or of the escape mechanism 200 and / or between the resonator mechanism 100 and the escape mechanism 200, at the level of the at least one pair of components, comprising a first component 22 and a second component 32, which respectively comprise a first friction surface 20 and a second friction surface 30 which are arranged to cooperate in contact with one another.

For example and without limitation, this first component 22 and this second component 32 are taken from: plate pin 6, anchor 7, anchor dart, anchor fork 8 with its horns 26, anchor pallet 72, 81, 82, escape wheel tooth 4, star ring 36 fixed to the plate, and the like.

In a particular embodiment, all the pairs of components with variable and / or discontinuous contact of such a regulating mechanism comprise antagonistic surfaces according to the characteristics of the invention, of which at least one component 22 or 32 comprises silicon carbide or its equivalent, that is to say a material comprising at least 90% by mass of silicon carbide SiC and at least one other material, taken from a list set out below.

The invention relates more particularly to the case of resonator mechanisms in which the energy to be transmitted during each pulse is less than 200 nJ.

More particularly, the invention relates more particularly to the case of resonator mechanisms in which both the energy to be transmitted during each pulse is less than 200 nJ, and the quality factor is greater than 1000.

The first friction surface 20 is the surface of a component which comprises silicon carbide which is either stoichiometric silicon carbide SiC, or non-stoichiometric silicon carbide Si _x C _y H _z , with x equal to 1, including between 0.8 and 5.0, and z between 0.00 and 0.70, or even a so-called equivalent material, that is to say comprising at least 90% by mass of silicon carbide SiC and at least one other material, taken from the following list whose proportions are displayed in mass:
alpha-SiC 6H, beta-SiC 3C, SiC 4H, fluorinated SiC, silicon carbonitride SiCN, aluminum 400 to 2000 ppm, iron less than 3000 ppm, boron and / or boron carbide B ₄ C and / or polyphenyl boron and / or decaborane B ₁₀ H ₁₄ and / or carborane B ₁₀ H ₁₂ C ₂ , the total of materials containing boron being between 0.04% to 0.14%, carbon less than 8000 ppm, vanadium carbide, zirconium carbide, alpha silicon oxynitride: alpha-SiAION doped yttrium, graphene, other impurities under 500 ppm.

However, impurities are often harmful for contact problems, and it is preferable to limit them to the lowest possible value, especially with regard to the iron which risks reacting with humidity to form disturbing oxides, than it is better to limit below 400 ppm. The other impurities should be limited, preferably below 100 ppm. Boron is only advantageous when it is made stable by a bond with another element, then boron alone is preferably avoided.

• Al₂O₃, ou CBN, ou TiO₂, ou verre, ou quartz, ou diamant, ou DLC ;
• ou bien un matériau à base de silicium pris parmi un groupe comportant le silicium Si, le silicium désoxydé, le dioxyde de silicium SiO₂, le silicium amorphe a-Si, le silicium polycristallin p-Si, le silicium poreux, ou un mélange de silicium et d'oxyde de silicium, le nitrure de silicium stoechiométrique Si₃N₄, le nitrure de silicium dans une composition dite non stoechiométrique Si_xN_yH_z avec x égal à 1 et y compris entre 0.8 et 5.0 et z compris entre 0.00 et 0.70, les oxynitrures Si_xO_yN_z, ;
• ou bien la deuxième surface de frottement 30 est la surface d'un composant qui comporte au moins un matériau à base de silicium pris, comme la première surface de frottement 20, parmi le carbure de silicium qui est, ou bien du carbure de silicium stoechiométrique SiC, ou bien du carbure de silicium non stoechiométrique Si_xC_yH_z, avec x égal à 1, y compris entre 0.8 et 5.0, et z compris entre 0.00 et 0.70, ou bien encore un matériau comportant au moins 90% en masse de carbure de silicium SiC et au moins un autre matériau pris parmi la liste suivante dont les proportions sont affichées en masse :
  alpha-SiC 6H, bêta-SiC 3C, SiC 4H, SiC fluoré, carbonitrure de silicium SiCN, aluminium 400 à 2000 ppm, fer inférieur à 3000 ppm, bore et/ou carbure de bore B₄C et/ou bore polyphénylique et/ou décaborane B₁₀H₁₄ et/ou du carborane B₁₀H₁₂C₂, le total de matériaux contenant du bore étant compris entre 0.04% à 0.14%, carbone inférieur à 8000 ppm, carbure de vanadium, carbure de zirconium, oxynitrure de silicium alpha : alpha-SiAION dopé yttrium, graphène, autres impuretés sous 500 ppm.

And the second friction surface 30 is the surface of a component which comprises at least one material ensuring good cooperation with the silicon carbide such as:

• Al ₂ O ₃ , or CBN, or TiO ₂ , or glass, or quartz, or diamond, or DLC;
• or else a silicon-based material taken from a group comprising silicon Si, deoxidized silicon, silicon dioxide SiO ₂ , amorphous silicon a-Si, polycrystalline silicon p-Si, porous silicon, or a mixture of silicon and silicon oxide, stoichiometric silicon nitride Si ₃ N ₄ , silicon nitride in a so-called non-stoichiometric composition Si _x N _y H _z with x equal to 1 and including between 0.8 and 5.0 and z ranging between 0.00 and 0.70, the oxynitrides Si _x O _y N _z ,;
• or else the second friction surface 30 is the surface of a component which comprises at least one silicon-based material taken, like the first friction surface 20, from silicon carbide which is, or else stoichiometric silicon carbide SiC, or non-stoichiometric silicon carbide Si _x C _y H _z , with x equal to 1, including between 0.8 and 5.0, and z between 0.00 and 0.70, or even a material comprising at least 90% by mass of silicon carbide SiC and at least one other material taken from the following list, the proportions of which are displayed by mass:
  alpha-SiC 6H, beta-SiC 3C, SiC 4H, fluorinated SiC, silicon carbonitride SiCN, aluminum 400 to 2000 ppm, iron less than 3000 ppm, boron and / or boron carbide B ₄ C and / or polyphenyl boron and / or decaborane B ₁₀ H ₁₄ and / or carborane B ₁₀ H ₁₂ C ₂ , the total of materials containing boron being between 0.04% to 0.14%, carbon less than 8000 ppm, vanadium carbide, zirconium carbide, oxynitride of alpha silicon: alpha-SiAION doped with yttrium, graphene, other impurities under 500 ppm.

The term “a-Si amorphous silicon” is understood here to mean silicon deposited by the PECVD process in a thin layer, from 50 nm to 10 micrometers, of amorphous structure; it can also be hydrogenated or doped type N or type P.

The term “polycrystalline silicon p-Si” is understood here to mean silicon deposited by the LPCVD process, composed of grains of microcrystalline silicon, the size of the grains being from 10 to 2000 nm; it can also be doped type N or type P. The modulus of elasticity E is close to 160 GPa.

The term “porous silicon” is understood here to mean a material with a pore size of 2 nm to 10 micrometers, produced according to a complex manufacturing process based on anodization (HF electrolyte and electric current).

More particularly, at least one of these first or second friction surfaces 20, 30 is constituted either by the surface of a solid element made of solid silicon carbide, preferably but not limited to in the stoichiometric SiC formulation, or else by the surface of a thin layer 21, 31, of silicon carbide in the stoichiometric formulation SiC, or according to a non-stoichiometric composition Si _x C _y H _z , with x equal to 1, including between 0.8 and 5.0, and z between 0.00 and 0.70. More particularly, z is between 0.04 and 0.70.

In the same way as for the first component 22 with its first friction surface comprising silicon carbide, the second friction surface 30 can be either the surface of a solid component, or the surface of a thin layer .

A particularly interesting application which is close to the invention is the cooperation of SiC lifts, in contact with Si + SiO ₂ wheels.

Another advantageous application relates to the so-called “solid silicon carbide” application, with SiC wheels, for example cut or laser, or the like, which are in friction against a monoblock anchor in Si + SiO ₂ , or against a conventional anchor. equipped with Si + SiO _{2 levers}

• roue en SiO₂, sous toutes ses formes, quartz massif SiO₂, Si + SiO₂, coopérant avec des palettes en carbure de silicium, sous toutes ses formes, en couches minces, ou carbure de silicium massif ;
• roues carbure, sous toutes ses formes, Si + carbure de silicium, carbure de silicium massif, coopérant avec des palettes en SiO₂, sous toutes ses formes, Si + SiO₂, SiO₂ massif notamment ;
• les palettes peuvent être d'une seule pièce avec l'ancre.

The combinations that can be used in watchmaking include:

• wheel in SiO ₂ , in all its forms, solid quartz SiO ₂ , Si + SiO ₂ , cooperating with pallets made of silicon carbide, in all its forms, in thin layers, or solid silicon carbide;
• carbide wheels, in all its forms, Si + silicon carbide, solid silicon carbide, cooperating with SiO ₂ vanes, in all its forms, Si + SiO ₂ , _{solid SiO 2 in} particular;
• the pallets can be in one piece with the anchor.

An advantageous application relates to an oxidized Si wheel, and solid SiC vanes, or else oxidized Si vanes covered with silicon carbide.

In an advantageous embodiment of the invention, the friction surface 20, 30, which is the surface of a component which comprises silicon carbide, is the surface of a component which comprises silicon carbide SiC, or still is made of silicon carbide SiC.

In particular, the first friction surface 20 and the second friction surface 30 are the surfaces of components 22 and 32 which each comprise silicon carbide or its equivalent as defined above. More particularly still, the first friction surface 20 and the second friction surface 30 are the surfaces of components which each comprise silicon carbide SiC, or else consists of silicon carbide SiC.

In a particular variant, the friction surface 20, 30, which is the surface of a component which comprises silicon carbide, is a surface of a layer of silicon carbide with a thickness of less than 2 micrometers. More particularly, the friction surfaces 20, 30 are each the surface of a layer of silicon carbide with a thickness of less than 2 micrometers.

The adhesion phenomenon concerns the surface of the material, and at the limit only at the level of the atomic layer; however, the inevitable abrasion phenomena make it necessary to have a sacrificial layer, also advantageously the friction surface 20, 30, which is the surface of a component which comprises silicon carbide is a surface of a layer of Silicon carbide greater than 0.5 micrometers thick. More particularly, the friction surfaces 20, 30 are each the surface of a layer of silicon carbide with a thickness greater than 0.5 micrometers.

Preferably, the thickness of such a layer of silicon carbide is between 50 and 2000 nm. More particularly, this so-called thin layer of silicon carbide has a thickness of between 50 nanometers and 500 nanometers.

In a particular variant of the invention, the friction surface 20, 30, which is the surface of a component which comprises silicon carbide is the surface of a layer of silicon carbide, which layer covers a substrate consisting of quartz or silicon or an oxide of silicon, or a mixture of silicon and silicon oxide. More particularly, the friction surfaces 20, 30, are each the surface of a layer of silicon carbide, which layer covers a substrate made of quartz or silicon or of a silicon oxide, or of a mixture of silicon. and silicon oxide.

In a particular variant, the friction surface 30, 20, antagonistic to that 20, 30, which is the surface of a component which comprises silicon carbide, is the surface of a component which comprises at least one material based on silicon taken from a group comprising silicon Si, silicon dioxide SiO ₂ , amorphous silicon a-Si, polycrystalline silicon p-Si, porous silicon, and is a surface of a layer consisting exclusively of one or several silicon-based materials taken from said group. More particularly, the friction surfaces 20, 30 are each the surface of a component which comprises at least one silicon-based material taken from a group comprising silicon Si, silicon dioxide SiO ₂ , amorphous silicon a- Si, polycrystalline silicon p-Si, porous silicon, and is a surface of a layer consisting exclusively of one or more silicon-based materials taken from said group.

The SiC / Si couple gives particularly interesting results, the friction torque is substantially constant, and this without requiring any lubrication. However, there are still friction losses, and the choice of fluid oil lubrication can reduce these friction losses, the sticking phenomena inherent in the presence of oil can be counteracted by a relatively low surface tension. .

Advantageously, the friction surface 20, 30, which is the surface of a component which comprises silicon carbide, has a roughness greater than or equal to 5 nanometers Ra, and more particularly greater than or equal to 9 nanometers Ra, more particularly still greater than or equal to 25 nanometers Ra, at least at the level of at least one contact surface. More particularly, this friction surface 20, 30 has a roughness greater than or equal to 5 nanometers Ra at the level of each contact surface. More particularly again, these friction surfaces 20, 30 each have a roughness greater than or equal to 5 nanometers Ra at the level of each contact surface.

In a particular variant, one of the two friction surfaces 20, 30 is smooth so as to avoid excessive friction (interpenetration of roughness, for example). The rough surface should be in relative displacement with a smooth surface so as to avoid wear. The surface roughness of the counterpart should preferably be low in order to limit wear, and its roughness is advantageously less than that of the contact surface, and more particularly but not limited to less than 5 nanometers Ra.

In another particular variant, to allow supra-lubrication, one of the surfaces is the surface of a component which comprises a first screened relief, in relief, for example in the form of a juxtaposition of pyramids, or the like, and the antagonistic surface is the surface of a component which has a second raster relief, which may or may not be analogous to the first raster relief, but which differs from it by a relative inclination of its screen direction with that of the first screen relief, of so as to prevent any embedding of one into the other.

The invention also relates to a method of making such an escape mechanism 200.

• dans une première alternative on applique une couche de carbure de silicium sur un substrat pour constituer une de ces première ou deuxième surface de frottement 20, 30 :
  • ou bien par un dépôt chimique en phase vapeur assisté par plasma PECVD,
  • ou bien par un dépôt chimique en phase vapeur CVD,
  • ou bien par un dépôt par pulvérisation cathodique « sputtering » ;
• ou dans une deuxième alternative on effectue une gravure profonde du composant dans un bulk massif de carbure de silicium.

According to this process:

• in a first alternative, a layer of silicon carbide is applied to a substrate to form one of these first or second friction surfaces 20, 30:
  • or by chemical vapor deposition assisted by PECVD plasma,
  • or by chemical vapor deposition CVD,
  • or by deposition by cathodic sputtering;
• or in a second alternative, a deep etching of the component is carried out in a massive bulk of silicon carbide.

These variants are not exclusive, they are the most economical. It is still possible to grow SiC in a sacrificial silicon mask, but the operation is difficult and expensive. It is also possible to carburize (or nitride if one wishes to obtain Si ₃ N ₄ for one of the antagonistic surfaces) a silicon wafer, but it is difficult to control the deformation of the mesh which can go as far as dislocation or a notable dimensional change.

More particularly, a component in silicon carbide is produced with a substrate to constitute the base of one of the first or second friction surfaces 20, 30, or else by sintering, or else by massive elaboration.

For the deposition of a layer comprising silicon carbide, or consisting of silicon carbide, one or more of the technologies known to those skilled in the art specializing in “MEMS” can in particular be used: LPCVD (chemical vapor deposition under atmospheric low pressure), PECVD (plasma assisted chemical vapor deposition), CVD (atmospheric pressure chemical vapor deposition), ALD (thin atomic film deposition), sputtering (cathodic sputtering), implantation ionic, and the like.

Preferably, the Si / C ratio is chosen between 0.8 to 1.2. More specifically, the Si / C value of 1 is stoichiometric

Preferably, when it is Si _x C _y H _z , a hydrogen concentration of between 2 to 30% of H is chosen.

Preferably, a usual Si substrate is chosen, without limitation.

As regards the sublayer, it is possible to choose, in a nonlimiting manner, SiO ₂ , typically in a thickness of between 50 and 2000 nm, or poly-Si, SiC, or the like.

The technological limitations associated with the deposition of silicon carbide are known to those skilled in the art in the field of MEMS.

Thus, the thickness of a layer of silicon carbide is preferably between 50 and 2000nm.

As regards the state of compression of silicon carbide, it is known to those skilled in the art of "MEMS" that increasing the concentration of Si reduces the stresses in the silicon carbide and can even make it compressive. It is known that materials exhibiting compressive stress generally promote a reduction in frictional wear. This corresponds to silicon carbide rich in Si. However, it is necessary to prevent too much silicon on the surface from oxidizing in the form of silicon oxide, because then we fall back into an adhesion phenomenon that we want. precisely fight.

For a good implementation of the invention, it is important that the silicon carbide layer adheres well to the substrate, and that the elastic moduli of the materials are not too far apart. The nature of the underlying materials is of less importance. If the silicon carbide layer exceeds a thickness of around 200nm, to prevent wear causing the silicon to appear too quickly, quickly oxidized to silicon oxide which is harmful for adhesion, the friction is determined by the very first peripheral nanometers of this layer of silicon carbide.

Monoblock SiC pallets can be produced by the same techniques as those used for the manufacture of polycrystalline ruby plies, known to those skilled in the art.

Furthermore, one can advantageously consider solid silicon carbide in friction against Si or SiO ₂ , for example for a silicon carbide vane against an SiO ₂ wheel.

• une faible dépendance du coefficient de frottement en fonction de la vitesse de frottement. Particulièrement utile dans le cas de l'échappement puisque la vitesse varie typiquement entre 0 et 3 cm/s.
• un coefficient de frottement stable en fonction de la vitesse et pression réduit le risque d'apparition d'effet stick-slip se traduisant généralement par une dégradation accélérée des matériaux en frottement.
• l'absence de risque de formation d'un troisième corps défavorable au frottement.
• une faible réactivité chimique du carbure de silicium, particulièrement dans sa forme stoechiométrique SiC, le rendant peu sensible aux nettoyages, à la dégradation, à l'interaction avec le milieu ambiant.
• une faible usure.

The invention has many advantages in the case of the non-lubrication of the exhaust:

• low dependence of the coefficient of friction as a function of the friction speed. Particularly useful in the case of the escapement since the speed typically varies between 0 and 3 cm / s.
• a coefficient of friction which is stable as a function of speed and pressure reduces the risk of the appearance of a stick-slip effect, generally resulting in an accelerated degradation of the friction materials.
• the absence of risk of formation of a third body unfavorable to friction.
• low chemical reactivity of silicon carbide, particularly in its stoichiometric form SiC, making it not very sensitive to cleaning, to degradation, to interaction with the ambient medium.
• low wear.

It will be noted that the solution proposed by the invention is dedicated to reducing adhesion phenomena (separation / normal displacement and tangential displacement) which are different from friction phenomena (tangential displacement only).
Silicon carbide also has the advantage of easy processing, particularly by coating in accordance with PECVD, in particular on silicon or silicon oxide. This deposition process is widely known and widespread in the silicon industry.

The present invention allows the use of silicon carbide in different forms: PECVD, CVD, “sputtering”, solid, sintered, and others.

Similar applications of the invention include friction of silicon carbide against non-limiting partners such as: Si, SiO ₂ , amorphous silicon a-Si, polycrystalline silicon p-Si, porous silicon.

The invention makes it possible to solve the sticking problem which hitherto hampered the development and industrialization of regulating mechanisms for watches with a quality factor greater than 1000, and it is understood that other watchmaking problems can also find an improvement. For example, the contact between the pin and the fork of the anchor in a traditional mechanism is also subject to sticking. More generally, this solution is applicable in all cases where the energies involved are low.

Claims (13)

Clockwork regulating mechanism (300), comprising, arranged on a plate (1), a resonator mechanism (100) with virtual pivot, around a main axis (DP), and with flexible guidance, of a quality factor Q greater than 1000, and an escape mechanism (200) which is subjected to a torque of motor means (400) that comprises a movement (500), said resonator mechanism (100) comprising an inertial element (2) arranged to oscillate relative to said plate (1), said inertial element (2) being subjected to the action of elastic return means (3) fixed directly or indirectly to said plate (1), and said inertial element (2) being arranged for cooperating indirectly with an escapement mobile (4) that comprises said escapement mechanism (200), characterized in that said inertial element (2) is arranged to cooperate indirectly with said escapement mechanism (200) free in the cycle of which the resonator mechanism (100) has at least one phase freedom where it is without contact with said escape mechanism (200), said regulating mechanism (300) comprising at least a pair of components comprising a first component (22) and a second component (32) respectively comprising a first surface of friction (20) and a second friction surface (30) arranged to cooperate in contact with each other, characterized in that a said first component (22) comprises, at its said first friction surface (20 ), silicon carbide which is either stoichiometric silicon carbide SiC, or non-stoichiometric silicon carbide Si _x C _y H _z , with x equal to 1, including between 0.8 and 5.0, and z between 0.00 and 0.70, or even a material comprising at least 90% by mass of silicon carbide SiC and at least one other material taken from the following list, the proportions of which are displayed by mass: alpha-SiC 6H, beta-SiC 3C, SiC 4H, fluorinated SiC, silicon carbonitride SiCN, aluminum 400 to 2000 ppm, iron less than 3000 ppm, boron and / or boron carbide B ₄ C and / or polyphenyl boron and / or decaborane B ₁₀ H ₁₄ and / or carborane B ₁₀ H ₁₂ C ₂ , the total of materials containing boron being between 0.04% to 0.14%, carbon less than 8000 ppm, vanadium carbide, zirconium carbide, alpha silicon oxynitride: alpha-SiAION doped yttrium, graphene, other impurities under 500 ppm,
and further characterized in that said second component (32) comprises, at its said second friction surface (30), at least one material ensuring good cooperation with the silicon carbide, among: - Al ₂ O ₃ , or CBN, or TiO ₂ , or glass, or quartz, or diamond, or DLC; - or a silicon-based material taken from a group comprising silicon Si less than 400 ppm by mass, deoxidized silicon, silicon dioxide SiO ₂ less than 8000 ppm by mass, amorphous silicon a-Si, silicon polycrystalline pSi, porous silicon, or a mixture of silicon and silicon oxide, stoichiometric silicon nitride Si ₃ N ₄ , silicon nitride in a so-called non-stoichiometric composition Si _x N _y H _z with x equal to 1 and including between 0.8 and 5.0 and z between 0.00 and 0.70, the oxynitrides Si _x O _y N _z ,; - Either the second friction surface 30 is the surface of a component which comprises at least one silicon-based material taken, such as the first friction surface 20, from among the silicon carbide which is, or else silicon carbide stoichiometric SiC, or non-stoichiometric silicon carbide Si _x C _y H _z , with x equal to 1, including between 0.8 and 5.0, and z between 0.00 and 0.70, or even a material comprising at least 90% in mass of silicon carbide SiC and at least one other material from the following list, the proportions of which are displayed by mass:
alpha-SiC 6H, beta-SiC 3C, SiC 4H, fluorinated SiC, silicon carbonitride SiCN, aluminum 400 to 2000 ppm, iron less than 3000 ppm, boron and / or boron carbide B ₄ C and / or polyphenyl boron and / or decaborane B ₁₀ H ₁₄ and / or carborane B ₁₀ H ₁₂ C ₂ , the total of materials containing boron being between 0.04% to 0.14%, carbon less than 8000 ppm, vanadium carbide, zirconium carbide, oxynitride of alpha silicon: alpha-SiAION doped yttrium, graphene, other impurities under 500 ppm. Regulating mechanism (300) according to claim 1, characterized in that said first component (22) and said second component (32) each comprise silicon carbide which is either stoichiometric silicon carbide SiC or alternatively carbide of non-stoichiometric silicon Si _x C _y H _z , with x equal to 1, including between 0.8 and 5.0, and z between 0.00 and 0.70, or even a material comprising at least 90% by mass of silicon carbide SiC and at at least one other material taken from the following list, the proportions of which are displayed by mass: alpha-SiC 6H, beta-SiC 3C, SiC 4H, fluorinated SiC, silicon carbonitride SiCN, aluminum 400 to 2000 ppm, iron less than 3000 ppm, boron and / or boron carbide B ₄ C and / or polyphenyl boron and / or decaborane B ₁₀ H ₁₄ and / or carborane B ₁₀ H ₁₂ C ₂ , the total of materials containing boron being between 0.04% to 0.14%, carbon less than 8000 ppm, vanadium carbide, zirconium carbide, alpha silicon oxynitride: alpha-SiAION doped yttrium, graphene, other impurities under 500 ppm Regulator mechanism (300) according to claim 2, characterized in that said first component (22) and said second component (32) each comprise silicon carbide. Regulating mechanism (300) according to one of claims 1 to 3, characterized in that said first friction surface (20) is formed by the surface of a solid element which is made of solid silicon carbide in the stoichiometric SiC formulation. Regulating mechanism (300) according to one of claims 1 to 4, characterized in that said second friction surface (30) is formed by the surface of a solid element made of solid silicon carbide. Regulating mechanism (300) according to claim 5, characterized in that said second friction surface (30) is formed by the surface of a solid element made of solid silicon carbide in the stoichiometric SiC formulation. Regulator mechanism (300) according to one of claims 1 to 6, characterized in that said resonator mechanism (100) is a rotary resonator with virtual pivot, around a main axis (DP), with flexible guide comprising at least two flexible blades (5), and comprises a plate pin (6) integral with said inertial element (2), in that said escape mechanism (200) comprises an anchor (7) pivoting about a secondary axis (DS) and comprising an anchor fork (8) arranged to cooperate with said plate peg (6), and is a free escape mechanism in the operating cycle of which said resonator mechanism (100) has at least one phase of freedom where said deck peg (6) is spaced from said anchor fork (8), and in that said first component (22) and said second component (32) are taken from said deck peg (6), an anchor (7), a sting of said anchor (7), a fork (8) of said anchor (7) or one of s horns (26), a pallet (72, 81, 82) of said anchor (7), an escape wheel tooth (4), a star (36) fixed to said plate (1) Regulating mechanism (300) according to one of claims 1 to 7, characterized in that said regulating mechanism (300) is devoid of lubricant. Regulating mechanism (300) according to one of claims 1 to 7, characterized in that said regulating mechanism (300) comprises a lubricant with a surface tension of less than 50 N / m. Clockwork movement (500) comprising at least one regulator mechanism (300) according to one of claims 1 to 9. Watch (1000) comprising at least one timepiece movement (500) according to claim 10 and / or at least one regulating mechanism (300) according to one of claims 1 to 9. Method for producing a regulating mechanism (300) according to one of claims 1 to 9, characterized in that each pair is produced consisting of a first friction surface (20) and a second friction surface (30) antagonistic comprising silicon carbide, and characterized in that a silicon carbide component is produced with a substrate to constitute said first friction surface (20) and / or said second friction surface (30) by sintering. Method for producing a regulating mechanism (300) according to one of claims 1 to 9, characterized in that each pair is produced consisting of a first friction surface (20) and a second friction surface (30) antagonistic comprising silicon carbide, and characterized in that a silicon carbide component is produced with a substrate to constitute said first friction surface (20) and / or said second friction surface (30), by elaboration in the form of 'a solid component with a thickness greater than 0.10 mm.

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