EP2107434B1 - Mechanical timer - Google Patents

Description

Field of the invention

The present invention relates to a novel high-precision and friction-optimized micromechanical component, in particular in the train of a mechanical timepiece, according to the preamble of claim 1. The present invention relates in particular to such a micromechanical component, which is part of an anchor escapement of a mechanical timepiece. Moreover, the invention relates to a timepiece in which such a micromechanical component is incorporated.

technical basics

A mechanical timepiece, as is well known as a pocket watch or wristwatch, usually comprises at least one gear train. In addition, forms in a conventional mechanical timepiece, the drive distribution member, the inhibition, the transition between the gear train and the oscillator (vibration or time division organ).

The task of the inhibition is to supply the vibrating organ, the balance, with a tiny amount of energy every time it passes the "dead spot". A "dead point" is the position of the balance at which it is nominally at rest, or the amplitude of the balance is nominally 0 ° (zero crossing). The balance oscillates evenly on both sides of the dead point with an amplitude  and releases a tooth of the escape wheel at each zero crossing. This allows the gear train and the hands to turn in small jumps with a regular frequency controlled by the balance.

Between the brief moments in which the escapement releases the gear, it rests, while the balance remains in constant motion until the energy stored in the tension spring is released. Just during the brief moment during the so-called uplift, a tiny amount of energy is returned to the balance via the escapement. The resulting jerky movements of the gear train can be observed, for example, as the second hand advances

Dozens of different inhibitions have already been proposed for the most uniform possible release of energy. Today, virtually all mechanical watches are equipped with the same type, namely the "Swiss lever escapement". In a "Swiss lever escapement", the two arms of the anchor each include an anchor stone ("pallet"), which usually consist of ruby, sapphire or garnet. These anchor stones are either inserted into the two arms of the anchor, or are made in one piece together with the anchor. The anchor stones take turns in each case a tooth of the escape wheel and hold it so firmly. Each time the balance passes the dead-end in one direction or the other, it engages the anchor fork via the so-called lever (ellipse). As a result, the anchor releases a tooth of the escapement wheel via its respective pallet, which thus advances briefly and returns a tiny fraction of energy across the armature to the lever block and thus the balance.

Apart from the brief moment in which the escapement wheel is connected to the balance wheel via the anchor fork, it oscillates as an oscillatory organ completely free and independent of its drive mechanism. This is a basic condition for the regular pace of the watch. The few types of inhibitors that have this advantage are called "free inhibitions." The anchor escapement is thus a free inhibition. Such inhibition constructions were developed only in the middle of the 18th century.

In the power transmission between the teeth of the escape wheel and the pallets of the armature, these two parts move under pressure against each other. At the beginning of the movement, a pallet is applied to an area of an escape wheel tooth, the so-called resting surface. As the pallet moves against the escape wheel, a frictional force occurs.

worin F_R die Reibungskraft, F_N die senkrecht zur Ebene der beiden Kontaktflächen auf die Körper wirkende Normalkraft und µ der Reibungskoeffizient (der Gleitreibung) ist. Dieser Koeffizient ist eine dimensionslose Zahl und bestimmt also, wie gross die Reibungskraft im Verhältnis zur Normalkraft ist.In order to move two bodies that lie against each other with plane-parallel flat surfaces and in which the two bodies are pressed against each other by a force, to move relative to each other, a force in the direction of movement must be applied. First, the static friction of the two bodies is overcome; when the force to overcome the stiction is sufficient, the bodies begin to move against each other, and to maintain a uniform motion, less force is sufficient. This power obeys the relationship $${\mathrm{F}}_{\mathrm{R}}\mathrm{=}\mathrm{\mu }\mathrm{\cdot }{\mathrm{F}}_{\mathrm{N}}$$

where F _{R is} the frictional force, F _{N is} the normal force acting on the bodies perpendicular to the plane of the two contact surfaces, and μ is the friction coefficient (the sliding friction). This coefficient is a dimensionless number and thus determines how large the friction force is in relation to the normal force.

It should be remembered in this context that forces are vectors and therefore directional; see. eg Kuchling, Taschenbuch der Physik, pp. 103ff, 1989 Publisher Harri Deutsch, Frankfurt / Main (Ger and).

In the anchor escapement, the frictional and normal forces are essentially transmitted by the torque of the escapement wheel drive. This torque is ultimately generated by the tension spring and transmitted via the gear train and the escapement wheel drive.

As will be described below, the friction between the pallets and the escape wheel poses a problem which affects the accuracy and the life of the movement. High friction reduces the amount of energy passed on to the balance; Accuracy and available power reserve are smaller than with low friction. In addition, the mentioned friction usually leads to a material removal, so wear, at the contact surfaces of pallets and the escape wheel, whereby the accuracy can be reduced and the parts in question must be replaced from time to time.

In FR 1 485 813 It is said that the teeth are chamfered by herniation wheels to create a contact surface between the teeth and the anchor pallets with a smaller width. But only beats FR 1 485 813 instead of this chamfering of teeth, to make the wheels even thinner, eliminating the need for chamfering. This then results in a much simpler production process of escapement wheels. However, the lesson of FR 1 485 813 no better solution to the friction problems.

In order to minimize wear and friction, oils with conventional escapements with steel escape wheel and ruby pallets are mandatory. The use of lubricants, in turn, requires that the movement must be serviced at regular intervals because the lubricants must be renewed and / or the escapement and the wheels must be cleaned. Finally, dust, but also moisture can settle on the contact surfaces, whereby the coefficient of friction change and thus the accuracy of the timekeeper can be influenced.

Therefore, it has been tried for a long time to stabilize the friction conditions between the escape wheel and the pallets and in particular to reduce the friction itself. For example, it has already been proposed to place small containers of oil at the end of the pallets, which then slowly spread over the friction surfaces. However, these and other measures have not brought a final improvement, so that the above-mentioned disadvantages of the prior art are still solved to an unsatisfactory extent.

Disclosure of the invention

The invention has therefore set itself the task of improving the life and also the precision of mechanical movements through a revision of the mechanical components, and in particular the revision of the anchor escapement from the ground up. In particular, it is an object of the invention to significantly reduce the friction of the pallets against the escape wheel, however at the same time to keep the wear of these parts to a tolerable level. In addition, the use of lubricants should be completely avoided, if possible. Finally, the objects of the invention with low cost, reproducible and manufacturing technology to be solved easily.

The present invention is defined in the first independent claim , Particular or preferred embodiments can be found in the dependent claims.

The invention is based on the basic idea of initially making the friction between the individual micromechanical components as small as possible. This principle results in particular in a micromechanical component, which is part of the anchor escapement, to extend the life and easier maintenance of the timepiece. In particular, according to this inventive idea, the contact surfaces of the two bodies (of the two micromechanical components) are transferred into a contact line or a contact point. In the anchor escapement, the pallets are inclined against the contact surface of the escape wheel tooth, so that not the flat side end face of the escape wheel tooth, but only the upper axis-parallel edge of the tooth rests against the pallet and slides transversely to the direction of the edge over this surface. Thus, the sliding friction of two surfaces in the movement of the timepiece is made possible by the friction of an edge, i. a (two-dimensional) line, replaced by a flat surface. According to equation 1, frictional forces are independent of the surface. However, this only applies on a macroscopic scale. For very small, especially rough contact surfaces, however, a direct dependence of the coefficient of friction on the size of the contact surface can be observed. This is scientifically explained by a micro-toothing of the two contact surfaces.

The invention is explained below on the example of an anchor escapement. However, it is explicitly pointed out at this point that this invention also relates to a micromechanical component in general.

According to the invention, the size of the contact surface between the pallets and the escape wheel tooth (or in general the size of the contact surface between a first and a second micromechanical component) is initially greatly reduced. For reasons of wear, the material of the metallic escape wheel must also be replaced by a harder material at the same time. This initially only affects the contact surfaces on the teeth of the escape wheel. When reducing the contact area changes at a constant torque the escapement wheel drive does not force the teeth. However, the "surface" pressure between the two parts increases very sharply, and there is a risk of increased wear on the contact surfaces. To forestall this foreseeable effect, in a preferred embodiment, the invention provides for the contact surfaces on the teeth of the escape wheel to be made by an extremely hard material. For this purpose, a hard material coating with diamond, in particular with nanocrystalline diamond, offers. Appropriate techniques for forming such extremely hard coatings have recently become known.

A next step to further reduce the friction in the armature escapement is the complete replacement of the previously existing metal escape wheel by one of a different material such as silicon, the wear resistance of the mentioned contact surfaces can be further increased, for example, by a suitable coating. Also in this case, a hard material coating can be used, with a silicon oxide such as SiO ₂ or a non-stoichiometric oxide having the formula Si _x O _y , where x and y are integers, as well as silicon carbides, silicon nitrides or diamond are particularly suitable. It should be emphasized in particular that finely crystalline or nanocrystalline and also amorphous coatings prove to be particularly suitable as a wear protection layer. The aim is therefore materials that can be deposited either amorphous or have a mean grain size of less than 50nm. In addition, a sliding friction coefficient of less than 0.2 is sought without the use of lubricants. With a diamond coating of the teeth of an existing silicon escapement wheel in contact with diamond pallets already achieved a coefficient of sliding friction in the order of 0.05 to 0.1; In comparison, the sliding friction coefficient of highly polished sapphire against steel with the aid of lubricants is about 0.15, ie about 50% -300% more. It should be noted that the Gleitreibzahl depends on the roughness of the respective surfaces. Furthermore, it is known that the sliding friction coefficient for many surfaces (for example, surfaces of silicon oxide and / or DLC layers (Diamond Like Carbon) highly dependent on the humidity, in diamond this effect is negligible.

One way of depositing such coatings is in the document EP 1 622 826 the applicant described.

mit F_N: auf die Fläche A wirkende Normalkraft
erforderlich, Hartstoffe einzusetzen, um dem erhöhten Verschleiss der Kontaktzonen entgegenzuwirken.A further reduction of the friction achieved by the invention in that the contact surface on the anchor wheel hook, ie the bent free end portion of each escape wheel tooth, or on the pallet is replaced by a line-shaped paragraph. Such a "line" friction can be compared to that of a skate. Here, as described above, the condition no longer applies to a sliding friction of two surfaces against each other that the frictional force is independent of the surface area of the body in contact. This is based on the fact that in the strictly mathematical sense it is no longer possible to speak of a surface if only one edge, ie a two-dimensional structure, shifts on a surface. In this case, the contact line, so a contact line, which must extend in the direction of movement, located at any point of the previous contact surface, ie centrally, laterally offset or at the edge. The width of the contact line to be generated generally depends on the production possibilities; a width of about 50 microns is considered sufficient for the reduction of friction. Again, because of the high mechanical compressive stress σ _D : $${\mathrm{\sigma }}_{\mathrm{D}}\mathrm{=}{\mathrm{F}}_{\mathrm{N}}\mathrm{/}\mathrm{A}$$

with F _N : acting on the surface A normal force
required to use hard materials to counteract the increased wear of the contact zones.

A further increase in the efficiency, ie a further reduction of the friction, is achieved if, according to the invention, the named contact straight line is first replaced by points, and finally if all points except one are omitted. It is understood that the resulting contact pressure can then assume inadmissibly high values, so that it is sometimes necessary, instead of providing a punctiform tip over the contact surface, to provide an elevation with a defined small area, For example, a conical elevation with a radius of rounding of about 100 to 20 microns, preferably between 80 and 50 microns at the top of the cone. In particular, at point-shaped contact points can easily be a contact pressure (pressure) p result, which is above the critical stress fracture of the hard material layer, the hard material thus breaks and the component catastrophically failed. For this reason, in addition to its wear-reducing hardness, the hard material layer must also have a very high mechanical breaking stress which is above the actually occurring compressive stress. In particular, materials which have a critical compressive stress of more than 0.5 GPa have proven to be suitable. It is particularly preferable to use materials which have a critical compressive stress of more than 2 GPa and in which the fracture stress is additionally isotropic, ie not direction-dependent. Particularly in the case of monocrystalline solids such as silicon it is known that the critical stress limits and thus also the critical compressive stress are strongly dependent on the crystal orientation. This effect is undesirable and can be avoided, inter alia, by the fact that the crystallites of the hard material layer are statistically oriented.

As is known, small dust particles and similar other contaminants can creep into the interior of the movement during the use of a timer. These dust particles can negatively influence the movements of the individual micromechanical components in the movement (in particular in the escapement). According to the invention, however, this problem can also be solved since, due to the extremely high mechanical compressive stress mentioned at the contact points between the armature gear and the pallet, a self-cleaning effect advantageously results. This is due to the fact that the pressure of the components in the contact zone is now so large that the contact surfaces act as quasi as scraping tools and thus can push impurities from the contact zone. However, it is a prerequisite that the wear on the contact surface remains tolerable despite the high pressure. This can be achieved by equipping the parts in contact with different coatings, as already mentioned above.

The manufacture of the escape wheel made of silicon or diamond can be done by the known modern methods. The particular shape on the contact surfaces of the escape wheel, namely an edge running in the direction of movement of the pallets, a row of dots or even individual points, can be achieved with photolithographic operations and structuring technologies of semiconductor technology, such as e.g. generate deep reactive ion etching (so-called DRIE method).

The invention also provides another advantage. By replacing at least the escape wheel, but also the anchor by workpieces made of a material such as silicon or diamond, the thermal expansion coefficient is greatly reduced. If it is 10 to 20 · 10 ^-6 K ^-1 for steel and 18 · 10 ^-6 K ^-1 for brass, it has only a value of about 1.1 · 10 ^-6 K ^-1 for diamond and for SiO 2 ₂ still 0.5 to 0.9 × 10 ^-6 K ^-1 (silicon: 2.6 × 10 ^-6 K ^-1 ). Because of these low values, the parts of the escapement of the present invention maintain their dimensions significantly better than the known escapements, with no excessive temperature variations. Thus, the general functionality of the timepiece is further improved significantly.

Description of exemplary embodiments

Further preferred embodiments, advantages and features of the subject invention will become apparent from the following description of exemplary embodiments, which will now be explained in more detail with reference to the figures of the drawing. These explanations and the drawings used thereto do not limit the invention, but merely give indications of possible embodiments.

Brief description of the drawings

• Fig. 1 eine schematische Draufsicht einer Ankerhemmung,
• Fig. 2A-2C drei Phasen beim Betrieb der Ankerhemmung gemäss Fig. 1,
• Fig. 3A-3C ein erstes Beispiel eines Ankerrades in perspektivischer Darstellung (Fig. 3A), eine perspektivische Detailzeichnung eines Radzahns (Fig. 3B) und einen Schnitt in der Ebene III-III in Fig. 3B (Fig. 3C),
• Fig. 4A-4C ein zweites Beispiel eines Ankerrades in perspektivischer Darstellung (Fig. 4A), eine perspektivische Detailzeichnung (Fig. 4B) eines Radzahns und einen Schnitt in der Ebene IV-IV in Fig. 4B (Fig. 4C),
• Fig. 5A-5C ein drittes Beispiel eines Ankerrades in perspektivischer Darstellung (Fig. 5A), eine perspektivische Detailzeichnung (Fig. 5B) eines Radzahns und einen Schnitt in der Ebene V-V in Fig. 5B (Fig. 5C),
• Fig. 6A-6C ein viertes Beispiel eines Ankerrades in perspektivischer Darstellung (Fig. 6A), eine perspektivische Detailzeichnung (Fig. 6B) eines Radzahns und einen Schnitt in der Ebene VI-VI in Fig. 6B (Fig. 6C),
• Fig. 7A-7D die Schnittansicht eines fünften, eines sechsten, eines siebten und eines achten Beispiels eines Ankerradzahns, wobei der Schnitt analog Fig. 6C gelegt ist,
• Fig. 8A und 8B eine perspektivische Ansicht bzw. einen Seitenansicht einer Ausführungsform eines Ankerradzahns mit punktförmiger Kontaktkonfiguration zwischen Palette und Ankerradzahn, und
• Fig. 9A und 9B eine Seitenansicht und eine Unteransicht einer Palette mit vorspringender Kontaktkante.

In the drawings:

• Fig. 1 a schematic plan view of an anchor escapement,
• Fig. 2A-2C three phases in the operation of the anchor escapement according to Fig. 1 .
• Figs. 3A-3C A first example of an escape wheel in perspective view ( Fig. 3A ), a perspective detail drawing of a Radzahns ( Fig. 3B ) and a section in the plane III-III in Fig. 3B (Fig. 3C )
• Fig. 4A-4C A second example of an escape wheel in perspective view ( Fig. 4A ), a perspective detail drawing ( Fig. 4B ) of a Radzahns and a section in the plane IV-IV in Fig. 4B (Fig. 4C )
• Figs. 5A-5C A third example of an escape wheel in perspective view ( Fig. 5A ), a perspective detail drawing ( Fig. 5B ) of a gear tooth and a section in the plane VV in Fig. 5B (Fig. 5C )
• Figs. 6A-6C A fourth example of an escape wheel in perspective view ( Fig. 6A ), a perspective detail drawing ( Fig. 6B ) of a wheel tooth and a section in the plane VI-VI in Fig. 6B (Fig. 6C )
• Figs. 7A-7D the sectional view of a fifth, a sixth, a seventh and an eighth example of an escape wheel tooth, the section analog Fig. 6C is laid,
• Figs. 8A and 8B a perspective view and a side view of an embodiment of an escape wheel tooth with point-shaped contact configuration between the pallet and the escape wheel tooth, and
• Figs. 9A and 9B a side view and a bottom view of a pallet with protruding contact edge.

Detailed description of the embodiment of the invention

The invention will be explained using the example of the Swiss lever escapement. However, it should be pointed out immediately that the invention applies to all mechanical inhibitions in movements and other time-keeping Applicable devices (eg timers), in which a frictional contact takes place in the escapement, and generally to all micromechanical components in which a relative movement to other components on the contact surfaces is formed.

It shows Fig. 1 schematically this escapement with a balance 10, an armature 12 and an escape wheel 14. The armature 12 has an input pallet 16 and an output pallet 18, which come alternately on each of an armature tooth 30 to the plant; the escape wheel is biased by the (not shown) elevator spring on the (also not shown) wheel train in the direction of rotation D. The resting surfaces of the anchor pallets 16, 18 do not point to the center of the escape wheel, but are at an angle Z of 12 ° to 15 ° thereto. This angle is called the draw angle. As a result, the armature 12 in the rest position) is reliably pressed by the escape wheel 14 against one of the limiting pins 22. Otherwise, the armature horn in the anchor fork would touch the security roller 24 of the balance 10 every time it is shaken.

The operation of this inhibition according to Fig. 1 should not be described in detail here; it is well known to the skilled person. Only a rough summary should be given.

In the Fig. 2A to 2C the course of the anchor escapement is shown in three phases. Out Fig. 2A It can be seen that when a pivoting movement of the armature in the direction of the arrow E about the axis 26, an edge movement between the pallet 16 and the front edge of the adjacent tooth 30A of the escape wheel 14 is initiated. When the pallet, which moves upwards relative to the tooth 30A, releases the tooth ( Fig. 2B ) slides the lower surface of the pallet 16 over the upper, leading edge of the tooth 30A and then over the rear edge ( Fig. 2C ). In all these movements a noticeable friction occurs. The invention has set itself the goal of reducing this friction and due to a small, as constant as possible, reproducible value.

In Figs. 3A to 3C a first example of the escape wheel is shown. The wheel 14-3 has the outer classic Form of an escape wheel and has teeth 30-3, one of which as an enlarged detail B in Fig. 3B is shown. Instead of two smooth surfaces which come into contact with the pallets, 30 raised, roof-shaped contact surfaces 36-3 are each provided with a central ridge 32-3 and 34-3 at the escape wheel tooth. This burr, which may also be arranged eccentrically without further ado, but has to run in the direction of movement of the pallets (not shown), is preferably produced from an ultra-hard material or coated with a suitable coating (eg with a hard material layer). The fillet radius of the free edge of the ridge is less than 25 μm.

In this case, the escape wheel 14-3 initially consists for example of silicon or a silicon-based material, and at least the inclined surfaces 36-3 and also the ridge 32-3 and 34-3 are made by depositing a hard covering of a silicon oxide, nitride or carbide, made of diamond or another hard material, so that they are extremely smooth and low-friction and are largely insensitive to wear due to their high hardness. For example, a hard coating is applied which provides values of HIT hardness (DIN EN ISO 14577) of at least 5 GPa, preferably greater than 10 GPa, and even more preferably greater than 50 GPa. These hardness values were determined in nanoindenter experiments. The coatings may be nanocrystalline or amorphous. Nanocrystalline coatings, for example, have an average particle size of less than 100 nm, preferably less than 20 nm. The thickness of the coatings should at least reach the value of the rounding diameter of 20 μm mentioned in this description and at least 100 μm on flat surfaces.

In FIGS. 4A to 4C a second example of the escape wheel is shown. The wheel 14-4 has the outer classic shape of an escape wheel and has teeth 30-4, one of which as enlarged detail B in Fig. 4B is shown. Here, in contrast to the execution according to Fig. 3 on the two contact tops of a tooth of the escape wheel no sharp edge between two roof-like surfaces present, but these two surfaces are curved cylindrically outwards, wherein the cylinder axis extends in the direction of relative movement between the pallets and the escape wheel tooth. In the operation of the timepiece, only the top one deletes and outermost layer 32-4 of the tooth, which again has only a small width extent, namely less than 50 microns when the contact with the pallet is made, on the latter.

Figs. 5A to 5C show in an analogous way like that Fig. 3 and 4 a third example of the inventive escape wheel. The escape wheel 14-5 in this embodiment is made, for example, of silicon or a silicon-based material by means of a photolithographic or other suitable method, as used, for example, in similar form in semiconductor technology. The surfaces 32-5 and 34-5 coming into contact with the pallets are laterally attached to or integrally formed with a support structure 36-5. The sectional drawing Fig. 5C is not true to scale; the width of the protruding surface 32-5 is only about 15 to 25 microns to keep the friction on the pallets very low. In addition, the escape wheel 14-5 may also be made of solid material, after which the surface portions 36-5 have been removed by etching, leaving the ridge 32-5 as a projection. Even with this method, a preferred width of this ridge of only about 15 to 25 microns can be achieved.

In the third example according to Figs. 5A-5C For example, the contact ridge 32-5 may also have a triangular cross-section instead of the illustrated rectangular profile, whereby the contact surface on the teeth of the escape wheel to a contact line (with correspondingly reduced friction) is executed. In general, however, one will seek a compromise between reduced friction and imminent wear by erosion.

Another example of the precision anchor escapement is in FIGS. 6A to 6C shown. It is an embodiment in which the upper surface 32-6 of the tooth 30-6 is at a certain angle (for example, an angle W between 2 ° and 10 °) to the perpendicular to the lateral surfaces 37-6 and 38-6 is trained. Through this training, a contact line and thus a very small contact area between the escape wheel 14-6 and the pallets of the anchor is achieved.

To supplement show the Figs. 7A, 7B, 7C and 7D whose representation is analogous to Fig. 5C is, cross sections of possible embodiments of the contact lines on the contact surfaces of the escape wheel. In Fig. 7A a ridge 40 of triangular cross-section is mounted on the base 42 of the tooth 30-7, such that one side of the triangle forms the continuation of a side surface of the tooth 30-7. This results in an asymmetrical arrangement of the contact line over the width of the tooth. Different in Fig. 7B here is a bump 44 of triangular cross-section on the base 46 of the tooth 30-7 ", and the tip of the bump 44 (radius of curvature of, for example, less than about 20 μm) may be any position over the width of the tooth 30-7". taking. The Figures 7C and 7D illustrate two more examples. In Fig. 7C corresponds to the survey 44 'of the survey 44 Fig. 7B , where it is truncated at the top. In Fig. 7D is the survey 49 arched at the top executed with a certain radius of curvature. Even in these two cases, the corresponding contact surfaces are relatively small.

There is a wide variety of possible arrangements of the contact surfaces or lines according to the invention, and one will select those arrangements which can be produced most conveniently and inexpensively.

An embodiment of the invention is in Figs. 8A and 8B shown. Here, the contact surface (always for contact between pallet and escape wheel tooth) is not replaced by a contact line, but by contact points 50 on which the pallet slides, as long as it is in contact with a tooth 30-8 of the escape wheel. These contact points 50 may be small cones of diamond inserted into the material of the tooth 30-8 - mostly silicon or a silicon based material - or produced by other techniques. Furthermore, these contact points can also be generated in such a way that first of all, for example silicon, an escape wheel geometry with line contact according to one of the preceding FIGS Figures 3-7 is generated and then the component is coated at least on its contact surfaces with a hard material layer. This hard material layer is now characterized in that it has a large surface roughness after coating. This can be achieved, for example, by the growth of a CVD diamond layer with large diamond crystals, eg polycrystalline diamond with mean grain sizes of more than 2 μm. Here, the protruding crystallites act like mountain peaks and thus act as contact points along the protruding ridge, and the contact points are defined self-aligning. The counterpart of this rough point bearing surface should be as smooth as possible, so that increased friction by micro-toothing is possible excluded. Here, for example, a nanocrystalline CVD offers itself (CVD - C hemical V apor D eposition - deposition from the gas phase) diamond layer with an average grain diameter of less than 50 nm and a correspondingly low surface roughness (average surface roughness R _z) of less than 100 nm.

Finally, in Fig. 9A a supervision and in Fig. 9B a side view of a pallet shown 16-9. On the front and the bottom of the pallet elongated elevations 30-9 are mounted, which terminate in ridges 32-9; these have a radius of curvature at the top, for example, less than 50 microns. These ridges come when running the timer in contact with flat mating surfaces on the escape wheel teeth, which are preferably coated with a hard material and a residual roughness (average roughness R _z ) of less than about 2 microns. Again, the escape wheel is made of a material such as silicon or diamond, but here with even contact surfaces on the teeth 30. The range 16-9 (also the corresponding output range 18-9 of the armature, not shown) according to Figs. 9A and 9B can consist of any dimensionally stable material, wherein the elevations 30-9 turn made of hard material, in particular of silicon or diamond, and wherein the silicon surfaces may be coated with one of the above hard materials.

In all the examples and embodiments described above, the escape wheel 14 is initially made of silicon or a silicon-based material, although other materials such as fiber-reinforced carbon, carbon nanotubes, silicon dioxide, silicon nitride, silicon carbide, diamond, etc., are possible, and the inclined surfaces 36 and also the ridges 32 and 34 are made by depositing a hard covering of a silicon oxide nitride or carbide, refined from diamond or another hard material, so that they are extremely smooth and low-friction and are largely resistant to wear due to their great hardness.

Except in Fig. 8 described production of self-aligning point contact by the deposition of a rough, crystalline hard material layer is the quality of the surfaces in contact preferably by appropriate procedures during coating with hard material and / or subsequent fine machining set such that a roughness (average roughness R _z according to DIN EN ISO 4287) of less than about 2.0 μm. As a result, the friction is greatly reduced. However, it should always be noted that the contact surface of both surfaces must not be so large that an adhesion between the two surfaces occurs. With a dimension of the contact surface below about 200 μm transverse to the direction of movement, for example, such an adhesion force is avoided.

The embodiments discussed above are merely examples and do not limit the invention. Many of the mentioned features can be combined with each other; the mention of all possible feature combinations would go beyond the scope of this document. So it is possible, to give just one example, that the escape wheel is made of silicon and the contact surfaces with the pallets are first coated with silicon nitride, on which a silicon carbide layer is then deposited. Also, not only the escape wheel but also the anchor with its pallets of diamond can be made for particularly valuable timepieces. Diamond is in all respects a particularly valuable material for these watch parts because it produces only low frictional forces and is exceptionally smooth, i. less rough, offers surfaces and is extremely resistant to wear due to its hardness.

The invention can be applied to all known clockwork inhibitions, although in the foregoing only the Swiss lever escapement was discussed.

Further embodiments, changes and further developments, which are within the knowledge and ability of the person skilled in the art, are included within the scope of the claims of the present invention.

Claims (16)

1. Mechanical chronometer with a first micromechanical component (14-3, 14-4, 14-5, 14-6) which comes into contact with at least one second micromechanical component (12) such that during operation of the mechanical chronometer a sliding relative movement occurs between at least one contact surface (32-3, 32-4, 32-5, 32-6, 40, 44, 44', 49, 50) of the first micromechanical component (14-3, 14-4, 14-5, 14-6) and a contact surface of the second micromechanical component (12),
   characterised in that
   at least the first micromechanical component (14-3, 14-4, 14-5, 14-6) is made of a hard and dimensionally stable non-metal,
   the at least one contact surface (32-3, 32-4, 32-5, 32-6, 40, 44, 44', 49, 50) of the first micromechanical component (14-3, 14-4, 14-5, 14-6), with the contact surface of the second micromechanical component (12), has the shape of a row of points extending in the direction of the said relative movement and having a width of at most 50 µm, and
   the at least one contact surface (32-3, 32-4, 32-5, 32-6, 40, 44, 44', 49, 50) of the first micromechanical component (14-3, 14-4, 14-5, 14-6) is finished in a friction-reducing and attrition-reducing way through application of a coating of nanocrystalline diamond or amorphous SiO₂.
2. Mechanical chronometer according to claim 1, characterised in that the said non-metal is silicon or a silicon-based material.
3. Mechanical chronometer according to claim 1, characterised in that the said non-metal is diamond.
4. Mechanical chronometer according to claim 1 or 2, characterised in that the surface roughness, defined as the average peak-to-valley height R_Z,, of the contact surfaces in contact that carry out a sliding relative movement is less than 2 µm.
5. Mechanical chronometer according to claim 1, characterised in that the nanocrystalline diamond has an average particle size of less than 100 nm.
6. Mechanical chronometer according to claim 1, characterised in that the nanocrystalline diamond has an average particle size of less than 20 nm.
7. Mechanical chronometer according to claim 1, characterised in that the particles have a statistical orientation.
8. Mechanical chronometer according to claim 1, characterised in that the material of the said coating has an HIT hardness according to DIN EN ISO 14577 of at least 5 GPa.
9. Mechanical chronometer according to claim 8, characterised in that the material of the said coating has an HIT hardness of more than 10 GPa, in particular preferably of more than 50 GPa.
10. Mechanical chronometer according to claim 1, characterised in that the material of the said coating is able to withstand non-destructively a critical compressive stress of more than 0.5 GPa, in particular preferably of more than 2 GPa.
11. Mechanical chronometer according to claim 1, characterised in that the critical compressive stress of the material of the said coating is directionally independent.
12. Mechanical chronometer according to one of the preceding claims, characterised in that the first micromechanical component or the second micromechanical component is part of a lever escapement for mechanical chronometers, the lever escapement comprising
    a pivotable lever (12) with lever pallets (16, 18), and
    an escape wheel (14) loaded with torque, which wheel has escape wheel teeth (30, 30A) outwardly protruding approximately radially over its circumference,
    the said pallets (16, 18), during operation of the escapement, ending up successively and alternately in contact with contact surfaces on the flanks of the escape wheel teeth (30, 30A) and a sliding relative movement occurring between one escape wheel tooth each (30, 30A) and one pallet each (16, 18), when the lever executes its pivot movement.
13. Lever escapement according to claim 12, characterised in that, with width dimensions of less than 50 µm, the contact surfaces are located on the teeth (30, 30A) of the escape wheel (14).
14. Lever escapement according to claim 12 or 13, characterised in that the contact surface with the width dimension of less than 50 µm is located on the pallets (16, 18).
15. Lever escapement according to one of the claims 12 to 14, characterised in that the flat contact surfaces on the pallets or respectively on the teeth of the escape wheel have a residual roughness, defined as the average peak-to-valley height R_z, of less than about 2 µm.
16. Mechanical chronometer with high-precision escapement, containing at least one mechanical component according to one or more of the preceding claims.

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