This application claims priority from European Patent Application No. 10166896.0 filed Jun. 22, 2010, the entire disclosure of which is incorporated herein by reference.
The invention relates to a single piece wheel set, for example a coaxial escape wheel set, and more specifically to a wheel set of this type made of micro-machinable or electroformable material.
In a known manner, the escapement of a mechanical timepiece movement, whether it is coaxial or a Swiss lever escapement, includes an escape wheel wherein the regularly spaced teeth undergo the shock of pallet-stones which are generally made of ruby.
An example of a coaxial escape system is presented in EP Patent No. 1 045 297. A mechanism of this type, as illustrated in
The first escape wheel 1 takes the form of a conventional Swiss lever escape wheel. The second escape wheel 11 also acts as escape pinion 15 by meshing with an intermediate wheel 17, which has the advantage of reducing the height of the mechanism.
The roller 19 of the balance (not shown) carries an impulse-pin 21 and an impulse pallet-stone 23. The impulse-pin 21 is for driving lever 25, in a to-and-fro motion, via the fork 27 thereof, whereas impulse pallet-stone 23 is for cooperating with the teeth 8 of the first escape wheel 1.
Lever 25 includes an impulse pallet-stone 24 which cooperates with the teeth 13 of the second escape wheel 11. Lever 25 also includes two other, respectively entry and exit locking pallets 26, 28 which cooperate with the teeth 8 of the first escape wheel 1.
The design of this coaxial escapement requires very high precision, particularly as regards the relative alignment of the first 1 and second 11 escape wheels, which makes it difficult to manufacture. Moreover, generally speaking, the gear trains of a two level timepiece like the usual wheel-pinion type always need to have perfect indexing between them.
It is an object of the present invention to overcome all of part of aforecited drawbacks by proposing a wheel set, such as for example a coaxial escape wheel set, wherein the problems of alignment are reduced and the inertia is decreased.
The invention therefore relates to a single piece wheel set including a first toothing formed at the periphery of a plate and a second toothing, wherein the second toothing is formed in a single piece with the plate of the first toothing so as to reduce any problems of alignment of one relative to the other and to decrease the overall mass of the wheel set and, in particular, a coaxial escape wheel set wherein the first toothing is arranged to cooperate with a pin and at least a first series of pallet-stones and a second toothing arranged to cooperate with a second series of pallet-stones.
The advantage of this wheel set is immediately clear, arising from the simplicity of design (single piece and less material) compared to two parts which are difficult to adjust in relation to each other at present.
In accordance with other advantageous features of the invention:
Moreover, the invention relates to a coaxial escape system for a timepiece including a lever that cooperates with a single piece coaxial escape wheel set according to one of the preceding variants, wherein the first toothing of the wheel set is arranged to cooperate with a pin integral with a balance and intended to cooperate with a first series of pallet-stones of the lever, the second toothing is intended to cooperate with a second series of pallet-stones of the lever and arranged to form the escape pinion.
Other features and advantages will appear clearly from the following description, given by way of non-limiting indication, with reference to the annexed drawings, in which:
Advantageously according to the invention, any problems of alignment between the first and second wheels are reduced by manufacturing a wheel set 100, 100′ that joins said wheels to each other to make a single piece. Consequently, only teeth 113, 113′ of one of the wheels are still necessary, which means that most of the plate of one of the two wheels is no longer needed, thereby also decreasing the mass of the escape wheel set 100, 100′ and, incidentally, the inertia thereof. For greater simplicity, the following explanation is given with reference to a coaxial escape wheel. It is nonetheless clear that the invention is applicable to any type of wheel set with at least two levels.
According to the first embodiment, shown in
As illustrated in
Of course, other elastic means may be envisaged. Such elastic means may, for example, take the form of that disclosed in FIGS. 10A to 10E of EP Patent No. 1 655 642, or that disclosed in FIGS. 2 to 5 of WO Patent No. 2007/099068, both documents being incorporated herein by reference.
Thus, advantageously according to the invention, rather than adding a second escape wheel 11 as in
Preferably, according to the invention, the teeth 113 are independent of each other and integral with arms 106. In the particular example of
According to the second embodiment, seen in
As illustrated in
Thus, advantageously according to the invention, rather than adding a second escape wheel 11 as in
Preferably according to the invention, teeth 113′ are independent of each other and integral with arms 106′. In the particular example of
These two embodiments of
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, although this is not an exhaustive list of compounds. Indeed, other compounds such as phosphorus may be added in smaller quantities. A micro-machinable material may be formed of silicon carbide, crystallised silicon, crystallised alumina or crystallised silica, although this list of compounds in not exhaustive.
The two types of manufacture will be presented respectively in
In a second step, at least one pattern 36 is etched in the top layer 33 until intermediate layer 34 is revealed so as to form at least a first toothing (teeth 108, 108′) of escape wheel set 100, 100′ at the periphery of a plate 103, 103′. This second step thus allows one or several first pattern(s) 101, 101′ of wheel set 100, 100′ to be made in top layer 33.
As illustrated in
In a third step, at least one second pattern 38 is etched in bottom layer 33 until the intermediate layer 34 is revealed, so as to form at least a second toothing (teeth 113, 113′) in a single piece with the plate 103, 103′ of the first toothing (teeth 108, 108′) of the escape wheel 100, 100′. This third step thus enables one or several second pattern(s) 111, 111′ of wheel set 100, 100′ to be formed in bottom layer 35.
As illustrated in
It remains only to release each two-level wheel set 100, 100′ thereby formed from substrate 31 and, possibly, the exposed parts of intermediate layer 34, so as to mount escape wheel 100, 100′ in the final escape system. Preferably, when escape wheel set 100, 100′ is formed from a silicon base, an additional oxidation step is performed so as to form at least one silicon dioxide part on the external surface thereof in order to increase the mechanical resistance of the wheel set.
The main electroforming steps consist in forming a mould and then filling the mould with the material, for example, by galvanoplasty. This type of electroforming is known by the abbreviation L.I.G.A. from the German term “röntgenLIthographie, Galvanoformung & Abformung”. There are several types of L.I.G.A. processes depending upon whether the mould with several levels is formed between each galvanoplasty process or formed entirely and then only subsequently filled. For the explanation below, the technique presented consists in forming each level, i.e. forming one level of the mould and filling it before passing to the next level. Of course, any type of electroforming process capable of forming a single piece wheel set with at least two distinct levels may be envisaged, whether or not it is of the L.I.G.A. type.
As illustrated in
As illustrated in
It remains only to release the two-level wheel set 100, 100′ thereby formed from substrate 41 and resins 47, 49, as illustrated in
Of course, this invention is not limited to the illustrated example but is capable of various variants and alterations that will appear to those skilled in the art. In particular, by way of alternative, the toothed wheels 101, 101′ could also include a felloe like the one referenced 9 in
Moreover, although the example of a coaxial escape wheel is given above, it is very clear that a wheel-pinion type wheel set of a gear train or even a normal escape wheel will have 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 possible to envisage least one additional level being formed underneath the plate, i.e. the opposite face to that carrying the second toothing 113, 113′, and/or above the latter.
Number | Date | Country | Kind |
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10166896 | Jun 2010 | EP | regional |
Number | Name | Date | Kind |
---|---|---|---|
20252 | Carpenter | May 1858 | A |
200533 | Hitchcock | Feb 1878 | A |
515862 | Eisen | Mar 1894 | A |
3949547 | Schneiter | Apr 1976 | A |
6082001 | Bettelini | Jul 2000 | A |
20060055097 | Conus et al. | Mar 2006 | A1 |
20080008051 | Marmy et al. | Jan 2008 | A1 |
20100308010 | Cusin et al. | Dec 2010 | A1 |
Number | Date | Country |
---|---|---|
1 045 297 | Oct 2000 | EP |
1 655 642 | May 2006 | EP |
1 850 193 | Oct 2007 | EP |
1 932 804 | Jun 2008 | EP |
2 228 692 | Sep 2010 | EP |
2 261 171 | Dec 2010 | EP |
2007099068 | Sep 2007 | WO |
Entry |
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European Search Report issued in corresponding application 10166896, completed Jan. 12, 2011. |
Number | Date | Country | |
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20110310709 A1 | Dec 2011 | US |