Patent Application
20170255164
This application claims priority from European Patent application 16158888.4 of Mar. 7, 2016, the entire disclosure of which is hereby incorporated herein by reference.
The invention relates to an adjustable auxiliary temperature compensation system and specifically such a system mounted on a balance wheel for a sprung balance spiral resonator.
Document EP 1 422 436, included with reference to this application, explains how to create a compensating balance spring comprising a silicon core coated in silicon dioxide and working alongside a balance wheel with a predetermined inertia to provide temperature compensation for said resonator assembly.
There are many advantages to manufacturing such a compensating balance spring, but they are subject to the disadvantages of any manufacturing process. In other words, the stage in which the balance springs are cut from a silicon plate is subject to a very low level of geometric dispersion, but this is still not negligible in the case of a compensating balance spring where a similar operation needs to be provided for each type of movement.
The object of this invention is to mitigate some or all of the disadvantages described above by proposing a balance wheel with adjustable temperature compensation to correct manufacturing differences in the components of a sprung balance spiral resonator.
To this end, the invention relates to a balance wheel comprising a rim connected to a hub by at least one arm, characterised in that the balance wheel comprises an adjustable auxiliary temperature compensation system mounted in the space defined by the rim to allow adjustable temperature compensation of the balance wheel.
This thus means that the adjustable auxiliary temperature compensation system can be adapted to a balance wheel for a watch movement that has already been designed and makes it possible to compensate individually for the dispersion inherent to each movement so as to make a sprung balance spiral resonator, for example, even less sensitive to temperature variations than would be the case with a compensating balance spring alone. As a result, the adjustable auxiliary temperature compensation system does not form part of the compensation assembly, but provides a means to refine the basic adjustment.
In accordance with other advantageous embodiments of the invention:
Furthermore, the invention relates to a resonator comprising a compensating balance spring where the compensating balance spring is connected to a balance wheel according to one of the previous embodiments.
Other specific features and advantages will become evident from the description below, provided by way of example and by no means as an exhaustive list, with reference to the attached drawings, in which:
As shown in
However, manufacturing variables and the fact that the compensating balance spring is not necessarily the silicon dioxide-coated silicon type have led the applicant to seek adjustment solutions. It thus became clear that there was a need for an adjustable auxiliary temperature compensation system to adjust the thermal coefficient of a resonator over a range of ±0.5 s.j−1.°−1 and that this should be able to be adapted to existing watch movements.
The invention thus proposes modifying a standard balance wheel comprising an uncut rim connected to the hub by means of at least one arm. According to the invention, the balance wheel advantageously comprises an adjustable auxiliary temperature compensation system mounted in the space defined by the uncut rim, or very close to the rim, to allow adjustable temperature compensation of the balance wheel.
This thus means that the adjustable auxiliary temperature compensation system makes it possible to adjust the thermal coefficient of each movement individually so as to make a sprung balance spiral resonator even less sensitive to temperature variations than would be the case with a compensating balance spring alone. As a result, the adjustable auxiliary temperature compensation system does not form part of the compensation assembly, but provides a means to refine the basic adjustment.
According to a first embodiment as illustrated in
It is clear that the object is to make it possible to adjust the variation in inertia of the balance wheel 15 in a predetermined manner as a function of temperature variations so as to correct manufacturing differences in the components of a sprung balance spiral resonator 1.
In the first embodiment illustrated in
To this end, the adjustable auxiliary temperature compensation system 13 comprises a fixing device 19 comprising adjustable positioning means between the hub 11 and the rim 14 to adjust the influence of the adjustable auxiliary temperature compensation system 13. In the example shown in
Furthermore, the fixing device 19 also comprises adjustable orientation means to further optimise the way in which the influence of the adjustable auxiliary temperature compensation system 13 is adjusted. In the example in
According to the first embodiment illustrated in
In addition, the bimetallic strip device 21 comprises a block 24 that is integral with the end of one of said at least one first and at least one second strips 23, 25, making it possible to increase the influence of the adjustable auxiliary temperature compensation system 13.
It is thus clear that by adjusting translational movement T and rotation R of the adjustable auxiliary temperature compensation system 13 in the radial recess 18 in an arm, it is possible to select a predetermined adjustment of the inertia of the balance wheel 15 as a function of temperature variations.
Of course, this invention is not limited to the illustrated example, but has various alternatives and modifications that will be clear to persons skilled in the art. In particular, the balance wheel 15 may comprise a plurality of adjustable auxiliary temperature compensation systems 13 and/or a counterweight may be used for each adjustable auxiliary temperature compensation system 13 as explained for the second embodiment. The balance wheel may also have a different geometry, such as, for example, fewer or more arms, a cut rim or a rim formed from a plurality of curved lobes. Finally, each adjustable auxiliary temperature compensation system 13 could be adapted with respect to its materials or the geometry used for the bimetallic strip device 21 and/or block 24 and/or fixing device 19 according to the required range of adjustment for the thermal coefficient.
According to a second embodiment as illustrated in
It is clear that the object is to make it possible to adjust the variation in inertia of the balance wheel 35 in a predetermined manner as a function of temperature variations so as to correct manufacturing differences in the components of a sprung balance spiral resonator 1.
In the second embodiment illustrated in
To this end, the adjustable auxiliary temperature compensation system 33 comprises a fixing device 39 comprising adjustable positioning means between the hub 31 and the rim 34 to adjust the influence of the adjustable auxiliary temperature compensation system 33. In the example shown in
Furthermore, the fixing device 39 also comprises adjustable orientation means to further optimise the way in which the influence of the adjustable auxiliary temperature compensation system 33 is adjusted. In the example in
According to the second embodiment illustrated in
In addition, the bimetallic strip device 41 comprises a block 44 that is integral with the end of one of said at least one first and at least one second strips 43, 45, making it possible to increase the influence of the adjustable auxiliary temperature compensation system 33.
It is thus clear that by adjusting translational movement T and rotation R of the adjustable auxiliary temperature compensation system 33 in the radial recess 38 of the feet 46, it is possible to select a predetermined adjustment of the inertia of the balance wheel 35 as a function of temperature variations.
Of course, this invention is not limited to the illustrated example, but has various alternatives and modifications that will be clear to persons skilled in the art. In particular, the balance wheel may also have a different geometry, such as, for example, fewer or more arms, a cut rim or a rim formed from a plurality of curved lobes. Furthermore, each adjustable auxiliary temperature compensation system 33 could be adapted with respect to its materials or the geometry used for the bimetallic strip device 41 and/or block 44 and/or fixing device 39 according to the required range of adjustment for the thermal coefficient.
Furthermore, according to a first alternative of the second embodiment, the balance wheel 35′ may comprise a plurality of adjustable auxiliary temperature compensation systems 331, 332 to balance the balance wheel 35′. Thus, as shown in
Thus, by adjusting the translational movement T1, T2 and rotation R1, R2 of each adjustable auxiliary temperature compensation system 331, 332 in the radial recess 381, 382 of the associated feet 461, 462, it is possible to select a predetermined adjustment of the inertia of the balance wheel 35′ as a function of temperature variations whilst achieving a better balancing result than in the example shown in
Finally, according to a second alternative of the second embodiment, the balance wheel 35″ may also comprise a counterweight 471, 472 for each adjustable auxiliary temperature compensation system 331′, 332′ so that the centre of mass of each adjustable auxiliary temperature compensation system 331′, 332′ is substantially immobile at a given temperature, such as, for example, 23° C., irrespective of the rotation R1, R2.
Thus, in the example shown in
In order to do this, each adjustable auxiliary temperature compensation system 331, 332 comprises a fixing device 391, 392 comprising adjustable positioning means with a radial recess 381, 382 between the two feet 461, 462 so that a position can be selected along the balance wheel 35″ by means of a translational movement T1, T2 between the hub 31 and the rim 34. It is thus clear that the adjustable auxiliary temperature compensation systems 331, 332 have a fixed working radius with respect to the axis of rotation of the balance wheel 35″, but this is free, subject to friction, during rotation.
Furthermore, the fixing device 391, 392 also comprises adjustable orientation means comprising a pivot 421, 422 mounted in the radial recess 381, 382 between the feet 461, 462 so that it is possible to select an angle with respect to the feet 461, 462 by means of a rotation R1, R2 of the base 371, 372 of the adjustable auxiliary temperature compensation system 331′, 332′.
It is thus clear that by adjusting the translational movement T1, T2 and rotation R1, R2 of each adjustable auxiliary temperature compensation system 331′, 332′ in the radial recess 381, 382 of the associated feet 461, 462, it is possible to select a predetermined adjustment of the inertia of the balance wheel 35″ as a function of temperature variations whilst achieving a better balancing result and ensuring that the centre of mass of the adjustable auxiliary temperature compensation systems 331′, 332′ remains substantially immobile compared to the example shown in
According to a third embodiment as illustrated in
It is clear that the object is to make it possible to adjust the variation in inertia of the balance wheel 55 in a predetermined manner as a function of temperature variations so as to correct manufacturing differences in the components of a sprung balance spiral resonator 1.
In the third embodiment illustrated in
To this end, the adjustable auxiliary temperature compensation system 53 comprises a fixing device 59 comprising adjustable positioning means between the hub 51 and the rim 54 to adjust the influence of the adjustable auxiliary temperature compensation system 53. In the example shown in
Furthermore, the fixing device 59 also comprises adjustable orientation means to further optimise the way in which the influence of the adjustable auxiliary temperature compensation system 53 is adjusted. In the example in
According to the third embodiment illustrated in
In addition, the bimetallic strip device 61 comprises a block 64 that is integral with the end of one of said at least one first and at least one second strips 63, 65, making it possible to increase the influence of the adjustable auxiliary temperature compensation system 53.
It is thus clear that by adjusting translational movement T and rotation R of the adjustable auxiliary temperature compensation system 53 in the radial recess 58 of the feet 66, it is possible to select a predetermined adjustment of the inertia of the balance wheel 55 as a function of temperature variations.
Of course, this invention is not limited to the illustrated example, but has various alternatives and modifications that will be clear to persons skilled in the art. In particular, the balance wheel 55 may comprise a plurality of adjustable auxiliary temperature compensation systems 53 and/or a counterweight may be used for each adjustable auxiliary temperature compensation system 53 as explained above for the second embodiment. The balance wheel may also have a different geometry, such as, for example, fewer or more arms, a cut rim or a rim formed from a plurality of curved lobes. Finally, each adjustable auxiliary temperature compensation system 53 could be adapted with respect to its materials or the geometry used for the bimetallic strip device 61 and/or block 64 and/or fixing device 59 according to the required range of adjustment for the thermal coefficient.
The bimetallic strip device must be sensitive to temperature variations for each embodiment of the balance wheel. The bimetallic strip device according to the invention preferably comprises at least one first strip based on silicon and at least one second strip based on metal.
Said at least one first strip based on silicon may comprise monocrystalline silicon, doped monocrystalline silicon, polycrystalline silicon, doped polycrystalline silicon, porous silicon, silicon oxide, quartz, silica, silicon nitride or silicon carbide. Of course, when the silicon-based material is in the crystalline phase, any crystalline orientation may be used.
Furthermore, said at least one second strip based on metal may comprise silver and/or magnesium and/or lead and/or thallium and/or nickel and/or copper and/or zinc and/or gold and/or aluminium and/or indium and/or vulcanite.
According to the invention, said at least one first and at least one second strips are arranged such that they are attached to one another to ensure that the curvature of the bimetallic strip device varies as a function of temperature. In effect, the band formed by said at least one first and at least one second strips curves as the temperature increases on the side on which the expansion coefficient is lowest.
In addition, this specifically means that the bimetallic strip device may comprise a plurality of first strips that are arranged such that they can be attached to a single second strip or, alternatively, that a plurality of second strips are arranged such that they can be attached to a single first strip.
In the case of the above embodiments, the required difference in expansion coefficient of the bimetallic strip device is approximately between 10 and 30 10−6 K−1 and it should also preferably have low sensitivity to magnetic fields. The combination of monocrystalline silicon and nickel/phosphorus alloy is used from preference. Of course, other alloys may be applied by galvanic growth technology, such as gold. It is also conceivable to assemble a silicon-based component on components machined in a more traditional manner such as copper alloys or non-magnetic steels.
In this way, monocrystalline silicon has a linear expansion coefficient α at 25° C. of around 2.5 10−6 K−1, whereas metals or metal alloys generally have linear expansion coefficients at 25° C. of between substantially 13 and 32 10−6 K−1. It is thus clear that the difference in expansion coefficient of the bimetallic strip device leads to high temperature sensitivity.
According to the invention, under ambient temperature and pressure conditions (ATPC) corresponding to a temperature of 25° C. and a pressure of 100 kPa, the bimetallic strip device preferentially forms a curved band.
As illustrated in the first and second embodiments above, said at least one first and at least one second strips are attached on top of one another by interlocking. In this way, interlocking means may be formed either by a groove-hook assembly or by notch-rib assemblies.
Of course, said at least one first and at least one second strips could be attached on top of one another by using an adhesive material or by electro-forming as an additional or alternative option.
Of course, this invention is not limited to the illustrated example, but has various alternatives and modifications that will be clear to persons skilled in the art. In particular, a plurality of identical or different bimetallic strip devices 21, 41, 411, 412, 61 could be distributed between each base 17, 37, 371, 372, 57 and each block 24, 44, 441, 442, 64.
In addition, each block 24, 44, 441, 442, 64 could alternatively be replaced by a weight fixed to the free end of one of said at least one first and/or at least one second strips in a similar manner to the adjustment screws 16, 36, 56, in other words screwed into said strips. The weight could thus be formed from a third material, which may, for example, be denser than the first two materials.
Finally, as explained above, the adjustable auxiliary temperature compensation system may be mounted on an arm or on the hub of the balance wheel. However, there is nothing to prevent the adjustable auxiliary temperature compensation system alternatively being mounted on the rim of the balance wheel, in other words on the internal or external diameter of the rim of the balance wheel.
| Number | Date | Country | Kind |
|---|---|---|---|
| 16158888.4 | Mar 2016 | EP | regional |
