EP2400351B1 - Single-piece mobile element for a clock piece - Google Patents

Description

Field of the invention

The invention relates to a single-piece mobile for example of the coaxial escapement type and more particularly to such a mobile in micro-machinable or electroformable material.

Background of the invention

In known manner, the escapement of a mechanical clockwork movement, whether Swiss-anchored or coaxial, comprises an escape wheel whose regularly spaced teeth are shocked by generally ruby pallets.

An example of a coaxial exhaust system is presented in the document EP 1 045 297 . Such a mechanism as illustrated in figure 11 comprises a mobile formed of a first 1 and a second 11 escape wheels. This second escape wheel 11, also called the impulse pinion, is mounted on the same axis 3. The angular position of the teeth 13 of the second escape wheel 11 is indexed to the angular position of the teeth 8 of the first wheel exhaust 1.

The first escape wheel 1 is in the form of a classic Swiss anchor escapement wheel. The second escape wheel 11 also acts as an escape pinion 15 meshing with an intermediate wheel 17, which has the advantage of reducing the height of the mechanism.

The large plate 19 of the balance (not shown) carries a plate pin 21 and a pulse pallet 23. The first 21 is intended to drive, in a back-and-forth motion, the anchor 25 via its fork 27 while the second 23 is intended to cooperate with the teeth 8 of the first escape wheel 1.

The anchor 25 comprises a pulse pallet 24 which cooperates with the teeth 13 of the second escape wheel 11. The anchor 25 also comprises two other pallets of rest 26, 28 respectively of entry and exit which cooperate with the teeth 8 of the first escape wheel 1.

The construction of such a coaxial escapement requires a very high accuracy, especially at the level of the relative alignments between the first 1 and second 11 exhaust wheels, which makes it difficult to manufacture. In addition, in general, the workings of a two-level timepiece like the usual wheel-pinion type have always required a perfect indexing between them.

The document US 2008 008 051 describes another escape mobile that has the same problems.

The document EP 2 261 171 discloses a composite mobile formed from at least one silicon element and a metal element from respectively reactive ion etching and electroforming.

Summary of the invention

The object of the present invention is to overcome all or part of the disadvantages mentioned above by providing a mobile such as a coaxial escapement mobile whose alignment problems are reduced and whose inertia is reduced.

For this purpose, the invention relates to a single-piece mobile having a first toothing formed at the periphery of a board formed of a hub connected to the first toothing with the aid of at least one arm and a second toothing characterized in that the second toothing is formed in one piece with the board of the first toothing and in that each tooth of the second toothing is independent of one another and protrudes from the board of the first to reduce the alignment problems with respect to each other and reduce the overall mass of the mobile and, in particular, such a mobile type exhaust coaxial whose first gear is arranged to cooperate with an anchor and at least a first pallet series and a second toothing arranged to cooperate with a second pallet series.

We immediately understand the interest of such a mobile simplicity of construction (monobloc and less material) compared to the two parts that are difficult to adjust relative to each other currently.

• chaque dent de la deuxième denture est solidaire dudit au moins un bras de la planche ;
• la deuxième denture comporte autant de dents que la planche comporte de bras ;
• la planche comporte une ouverture destinée à coopérer avec un axe afin de monter à rotation ledit mobile d'échappement coaxial ;
• l'ouverture comporte des moyens de fixation à déformation élastique afin de serrer l'axe sans exercer de contrainte destructive sur la planche ;
• l'ouverture comporte des moyens de fixation à déformation plastique afin de serrer l'axe sans exercer de contrainte destructive sur la planche ;
• le mobile peut être en métal ou en un alliage métallique ou à base de silicium.

According to other advantageous features of the invention:

• each tooth of the second toothing is secured to said at least one arm of the board;
• the second set of teeth has as many teeth as the board has arms;
• the board comprises an opening intended to cooperate with an axis in order to rotate said coaxial escapement wheel;
• the opening comprises fastening means with elastic deformation to clamp the axis without exerting destructive stress on the board;
• the opening comprises fixing means plastic deformation to tighten the axis without exerting destructive stress on the board;
• the mobile may be metal or a metal alloy or silicon-based.

In addition, the invention relates to a coaxial exhaust system for a timepiece comprising an anchor intended to cooperate with a monobloc coaxial escapement mobile according to one of the preceding variants, the first toothing of the mobile being arranged to cooperate with a peg integral with a rocker and being intended to cooperate with a first pallet series of the anchor, the second toothing being intended to cooperate with a second pallet series of the anchor and arranged to form the pinion 'exhaust.

Brief description of the drawings

• les figures 1 à 4 sont des représentations des étapes successives d'un procédé de fabrication d'un mobile d'échappement selon un premier mode de réalisation de l'invention ;
• les figures 5 à 8 sont des représentations des étapes successives d'un procédé de fabrication d'un mobile d'échappement selon un deuxième mode de réalisation de l'invention ;
• la figure 9 est une représentation en perspective d'un mobile d'échappement coaxial selon une première variante de l'invention ;
• la figure 10 est une représentation en perspective d'un mobile d'échappement coaxial selon une deuxième variante de l'invention ;
• la figure 11 est une représentation en perspective d'un système d'échappement du type coaxial.

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 Figures 1 to 4 are representations of the successive steps of a method of manufacturing an escape wheel according to a first embodiment of the invention;
• the Figures 5 to 8 are representations of the successive steps of a method of manufacturing an escape wheel according to a second embodiment of the invention;
• the figure 9 is a perspective representation of a coaxial escapement mobile according to a first variant of the invention;
• the figure 10 is a perspective representation of a coaxial escapement mobile according to a second variant of the invention;
• the figure 11 is a perspective representation of a coaxial type exhaust system.

Detailed Description of the Preferred Embodiments

Advantageously according to the invention, the problems of alignment between the first and second wheels are reduced by manufacturing a mobile 100, 100 'grouping said wheels integrally, that is to say in one piece. As a result, only the teeth 113, 113 'of one of the wheels are still necessary, which means that most of the board of one of the two wheels is no longer useful, thereby also allowing the weight of the moving part to be reduced. exhaust 100, 100 'and, incidentally, its inertia. For simplicity, the following explanation is made from a coaxial escape wheel. However, it is understood that any type of mobile at least two levels is applicable to the present invention.

As illustrated in Figures 9 and 10 two embodiment examples according to the invention of monobloc coaxial exhaust mobiles 100, 100 'are presented. These mobiles 100, 100 'comprise two distinct patterns on each level.

According to the first embodiment, visible to the figure 9 , the first pattern forms a toothed wheel 101 corresponding to the first escape wheel 1 of the figure 11 . It comprises a board 103 forming a hub 102, the center of which has an opening 104 and from which the arms 106 leave each end of which forms a tooth 108 corresponding to a tooth 8 of the figure 11 . A board 103 is thus obtained comprising a first toothing at its periphery.

As illustrated in figure 9 , the opening 104 comprises elastic fixing means 105 intended to cooperate radially with an axis of the type of that referenced 3 to the figure 11 by elastic deformation in order to rotatably mounting the escape wheel 101 and, consequently, the escapement wheel 100. These resilient fixing means 105 are formed by slender portions made by recessing a portion of the hub 102. The slender portions are used to tighten the axis, that is to say, to secure the mobile 100 of the latter, without subjecting the rest of the board 103 stress.

Of course, other elastic means are conceivable. Such elastic means may, for example, take the form of those disclosed in the Figures 10A to 10E of the document EP 1 655 642 or those disclosed in the Figures 2 to 5 of the document WO 2007/099068 which documents are incorporated by reference into the present description.

Thus, advantageously according to the invention, instead of bringing back a second escape wheel 11 as in the figure 11 , the mobile 100 being integral, the second unit 111, projecting from the first 101, is formed solely by a second toothing formed of teeth 113 corresponding to the teeth 13 of the figure 11 .

Preferably according to the invention, the teeth 113 are independent of each other and are integral with the arms 106. In the particular example of the figure 9 it is noted that each tooth 113 is integral with a separate arm 106. It is thus clear that the second toothing has as many teeth 113 as the board 103 has arms 106. However, this feature is not essential, there could very well be several teeth 113 on a single arm 106.

According to the second embodiment, visible to the figure 10 , the first pattern forms a toothed wheel 101 'corresponding to the first escape wheel 1 of the figure 11 . It comprises a board 103 'forming a hub 102' whose center has an opening 104 'and from which the arms 106' leave each end forming a tooth 108 'corresponding to a tooth 8 of the figure 11 . A board 103 'having a first toothing at its periphery is thus obtained.

As illustrated in figure 10 , the opening 104 'comprises plastic fixing means 107 intended to cooperate radially with an axis of the type of that referenced 3 to the figure 11 in order to rotatably mount the escape wheel 101 'and, therefore, the escape wheel 100'. These plastic fixing means 107 are formed by a washer made of metallic material enabling the mobile 100 'to be driven against said axis by plastic deformation without stressing the board 103'. Of course, other plastic fixing means are possible.

Thus, advantageously according to the invention, instead of bringing back a second escape wheel 11 as in the figure 11 , the mobile 100 'being integral, the second pattern 111', projecting from the first 101 ', is formed solely by a second toothing formed of teeth 113' corresponding to the teeth 13 of the figure 11 .

Preferably according to the invention, the teeth 113 'are independent of each other and are integral with the arms 106'. In the particular example of the figure 10 it will be noted that each tooth 113 'is integral with a separate arm 106'. It is therefore clear that the second set of teeth has as many teeth 113 'as the board 103' has arms 106 '. However, this characteristic is not essential, it could very well be several teeth 113 'on a single arm 106'.

These two embodiments of Figures 9 and 10 can be trained using a lot of different materials. However, an electroformable material, on the one hand, or a micro-machinable material, on the other hand, are preferred. Indeed, to date, the reactive ion etching and electroforming type LIGA are the only processes capable of producing parts with the precision of the order of a few microns necessary for the proper operation of the coaxial mobile 100, 100 '. However, any other process that can meet the same manufacturing tolerances is applicable.

An electroformable material may be formed with gold and / or copper and / or silver and / or indium and / or platinum and / or palladium and / or nickel without these compounds being exhaustive. Indeed, other compounds such as phosphorus can be added in a smaller amount. A micro-machinable material can be formed by silicon carbide, crystallized silicon, crystallized alumina or crystallized silica without these compounds being equally exhaustive.

Both types of manufacturing will be presented respectively to Figures 1 to 4 and 5 to 8 . The Figures 1 to 4 present successive main steps of a micro-machining for a better understanding. Preferably, the method comprises a first step consisting in providing a substrate 31 comprising an upper layer 33 and a lower layer 35 made of micro-machinable materials which are interconnected by an intermediate layer 34. This type of substrate 31 is also known. under the abbreviation SOI from the English term "Silicon On Insulator".

In a second step, etching of at least one pattern 36 in the upper layer 33 to find the intermediate layer 34 to form at least a first set of teeth (teeth 108, 108 ') of the escape wheel 100 , 100 'at the periphery of a board 103, 103'. This second step thus makes it possible to form one or more first pattern (s) 101, 101 'of the mobile 100, 100' in the upper layer 33.

As illustrated in figure 2 a mask 37 is formed, for example by photolithography, to protect the part of the upper layer 33 that it is desired to keep and, as illustrated by broken lines, the upper part of the substrate 31 is subjected to an anisotropic etching of the type deep reactive ion etching also known by the abbreviation DRIE from the English term "Deep Reactive Ion Etching". As illustrated in figure 3 the first pattern 36 having a first level 101, 101 'of at least one escape wheel 100, 100' is obtained.

In a third step, etching of at least one second pattern 38 in the lower layer 33 until the layer is exposed. intermediate 34 to form at least one second toothing (teeth 113, 113 ') integrally with the board 103, 103' of the first toothing (teeth 108, 108 ') of the escape wheel 100, 100'. This third step thus makes it possible to form one or more second pattern (es) 111, 111 'of the mobile 100, 100' in the lower layer 35.

As illustrated in figure 3 a mask 39 is formed, for example by photolithography, to protect the part of the lower layer 35 which it is desired to keep and, as illustrated by broken lines, the lower part of the substrate 31 is subjected to an anisotropic etching of the type deep reactive ion etching (DRIE). As illustrated in figure 4 the second pattern 38 having at least one second level 111, 111 'is formed integrally with one of the first levels 101, 101' formed in the preceding steps.

It remains more than to release each mobile 100, 100 'on two levels thus formed of the substrate 31 and, possibly, the uncovered portions of the intermediate layer 34 to mount the escape wheel 100, 100' in the system of definitive escape. Preferably, when the escape wheel 100, 100 'is formed based on silicon, an additional oxidation step is performed in order to form at least a portion of silicon dioxide at its outer surface for the purpose of make it more mechanically strong.

The Figures 5 to 8 present successive main stages of electroforming for better understanding. Preferably, the method comprises a first step of providing a substrate 41 having an electrically conductive upper layer. This layer can be obtained by the deposition of an electrically conductive material on an insulating material or in that the substrate is formed of an electrically conductive material.

The main steps of electroforming consist in forming a mold and then filling the mold with a material, for example, using electroplating. This type of electroforming is known by the abbreviation LIGA from the German terms "röntgenLIthographie, Galvanoformung &Abformung". There are several types of LIGA-type processes depending on whether the multi-level mold is formed between each electroplating or is formed entirely to be filled only after. For the explanation below, the technique presented consists in forming each level, that is to say forming a level of the mold and filling it before going to the next level. Of course, any type of electroforming, LIGA type or not, capable of forming a mobile unit in at least two distinct levels is possible.

As illustrated in Figures 5 and 6 , firstly, the first level 47 of the mold is formed using, for example, a photolithography of a resin as illustrated in FIG. figure 5 . At least one cavity of corresponding shape is formed at the first pattern 101, 101 ', ie at least one first toothing (teeth 108, 108') of the escape wheel 100, 100 'at the periphery of the board 103, 103 '. The first level is then filled by electroplating a metal material 46.

As illustrated in figure 7 similarly to the first time, in a second step, the second level 49 is formed using, for example, also a photolithography of a resin. At least one recess of corresponding shape is formed at the second pattern 111, 111 ', ie at least one second toothing (teeth 113, 113') of the escape wheel 100, 100 'and communicating with said at least one cavity of the first level 47. The second level 49 is then filled by electrodeposition of a metallic material 48.

It remains more than to release the mobile 100, 100 'on two levels thus formed of the substrate 41 and the resins 47, 49 as illustrated in FIG. figure 8 in order to mount the escape wheel 100, 100 'in the final exhaust system. In the example of an escapement wheel 100, 100 'obtained by electroforming, it is understood that it is no longer necessary to form the elastic or plastic fixing means 17 because the metal material can directly be driven on the axis by its opening 104, 104 '.

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. In particular, alternatively, it is also conceivable that the toothed wheels 101, 101 'may comprise a serge such as that 9 of the figure 11 without departing from the scope of the present invention.

Moreover, even if the example of a coaxial escapement wheel is presented above, it is obvious that a wheel-gear wheel of a cogwheel or even a usual escape wheel will present the same advantages. The first toothing 108, 108 'would be that of the wheel and the second toothing 113, 113' that of the pinion or vice versa.

Finally, it must be understood that at least two levels are achieved in a single piece. Thus, it is perfectly conceivable that at least one additional level is formed under the board, that is to say the face opposite to that supporting the second toothing 113, 113 ', and / or above it.

Claims (9)

1. Single piece coaxial escape wheel set (100, 100') including a first toothing (108, 108') formed at the periphery of a plate (103, 103'), formed of a hub (102, 102') connected to the first toothing via at least one arm (106, 106'), the first toothing (108, 108') is arranged to cooperate with a pin and at least a first series of pallet-stones, and a second toothing (113, 113') arranged to cooperate with a second series of pallet-stones, characterized in that the second toothing (113, 113') is formed in a single piece with the plate (103, 103') of the first toothing (108,108') and in that each tooth (113, 113') of the second toothing is independent of the others and projects relative to the plate (103, 103') of the first toothing (108, 108').
2. Wheel set (100, 100') according to the preceding claim, characterized in that each tooth (113, 113') of the second toothing is integral with said at least one arm of the plate (103, 103').
3. Wheel set (100, 100') according to the preceding claim, characterized in that the second toothing includes as many teeth (113, 113') as the plate (103, 103') has arms (106, 106').
4. Wheel set (100, 100') according to any of the preceding claims, characterized in that the plate (103, 103') includes an opening (104, 104') intended to cooperate with an arbour (3) for rotatably mounting said coaxial escape wheel set (100, 100').
5. Wheel set (100) according to the preceding claim, characterized in that the opening (104) includes securing means (105) that deform elastically to grip the arbour (3) without exerting any destructive stress on the plate (103).
6. Wheel set (100') according to claim 4, characterized in that the opening (104') includes securing means (107) that deform plastically to grip the arbour (3) without exerting any destructive stress on the plate (103').
7. Wheel set (100, 100') according to any of the preceding claims, characterized in that it is made of metal or a metal alloy.
8. Wheel set (100, 100') according to any of claims 1 to 6, characterized in that it is formed in a silicon-based material.
9. Coaxial escape system for a timepiece, including a lever (25) for cooperating with a single piece coaxial escape wheel set (100, 100') according to any of the preceding claims, wherein the first toothing (108, 108') of the wheel set (100, 100') is arranged to cooperate with a pin (23) integral with a balance and intended to cooperate with a first series (26, 28) of pallet-stones of the lever (25), the second toothing (113, 113') is intended to cooperate with a second series (24) of pallet-stones of the lever (25) and arranged to form the escape pinion.

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