The present invention relates to a spiral-spring and balance wheel regulating member including a shaft mounted pivotably on the frame of a timepiece, in which the spiral spring of the regulating member includes at least one blade located in a plane, whose inner end is designed to be fixed to the pivot shaft and whose outer end is made in one piece with a member for connection to the frame, the rigidity of this connecting member being substantially greater than that of the spiral. The invention also relates to a timepiece movement or to a timepiece comprising a regulating member of this kind.
There is a plurality of known methods of fastening the outer end of the spiral spring to the frame of the timepiece. As a general rule, this end is fixed, unlike the inner end which is fastened to a collet pressed onto the balance wheel shaft and which oscillates with the spiral-spring and balance wheel regulating member. In most cases, the outer end of the spiral is connected to a fixing stud or flange which is then fastened to a balance bridge.
One method of fastening the end of the spiral spring to a stud is to place it in a hole provided for this purpose in the stud, and then to secure it with a pin or by bonding. The stud is then inserted into a corresponding housing and fixed in position by pressing or by means of a screw.
The position of the spiral spring with respect to the balance wheel shaft must be adjusted in a precise way, because any eccentricity of the spiral spring or any departure from perpendicularity with respect to this shaft gives rise to serious timekeeping faults, particularly in relation to the isochronism of the regulating member. The stud must therefore be perpendicular to the plane of the spiral spring and must be positioned in a precise way to ensure the concentric development of the spiral spring. In the case of a conventional spiral spring made from an alloy, when the outer end of the spiral spring has been fixed to the balance bridge, directly or by means of an angular adjustment member, any defects created in the ideal three-dimensional shape of the spiral spring are corrected by plastic deformation of the outer end of the spiral spring. This is a highly complex operation which can only be performed by an experienced watchmaker. Moreover, this method of correction is evidently unsuitable for spiral springs made from fragile materials such as silicon, as this kind of material cannot be deformed in a plastic way.
Spiral-spring and balance wheel regulating members in which the outer end of the spiral spring is made in one piece with a frame connection member and which have a substantially greater rigidity than the spiral spring have been described in EP 1 515 200 for example, and also in WO 2006/123095 and EP 2 151 722. However, the proposed methods of fixing the outer end are still related to the conventional stud fixing method, in that they provide only a single attachment point which cannot ensure that the spiral spring, in its rest position, will retain the three-dimensional integrity of its initial shape after it has been fixed.
Thus these solutions cannot overcome the problem of fixing the outer end of a spiral spring in such a way that no correction is needed after fixing. This is because, when these conventional fixing methods are used, it is impossible to ensure that there will be no deformation in the spiral spring, that the spiral spring will maintain a concentric development with respect to the balance wheel pivot axis during the oscillation of the spiral-spring and balance wheel regulating member, or that the spiral spring will remain perpendicular to this axis.
If the spiral spring is made from a fragile material such as silicon, diamond or quartz, adjustment of the spiral spring by plastic deformation becomes impossible, and therefore the use of a stud requires extremely narrow manufacturing tolerances and a robust stud and spring assembly to ensure that the axis of the stud and the plane of the spiral spring are completely perpendicular to each other, or as nearly perpendicular as possible. This clearly gives rise to major difficulties in industrial production. Indeed, the clamping of the stud in its housing, by means of a screw for example, is in itself capable of changing the orientation of the stud and thus modifying the initial three-dimensional shape of the spiral spring.
It has been proposed, in EP 1 918 791 for example, that the stud be provided with means for modifying its angular or radial position, in order to correct defects in the concentric development of the spiral spring without the need for plastic deformation of the spiral spring. However, this solution cannot correct defects in the perpendicularity of the spiral spring with respect to the axis of the balance wheel. This solution also requires a high degree of skill for the very precise adjustment of an element which is located at the end of a spiral spring and which is therefore subject to the action of a large lever arm.
The object of the present invention is to overcome, at least partially, the aforementioned drawbacks.
For this purpose, the invention proposes a spiral-spring and balance wheel regulating member as claimed in claim 1.
Various embodiments of the regulator are defined by claims 2 to 17.
A timepiece movement according the invention is defined by claim 18.
A timepiece according the invention is defined by claim 19.
Advantageously, the profile and angular extension of the complementary bearing surfaces of the connecting member and of the frame or of a member for the angular positioning of the regulating member on the frame have a shape and size such that the three-dimensional integrity of the initial shape of the spiral spring is preserved in the resting state, after the complementary bearing surfaces have been fixed to each other.
The angular extension of the bearing surfaces may be large. It may be as great as 360°, which will provide an extremely stable support. Such complementary bearing surfaces can be produced with a very high degree of precision. For a given manufacturing tolerance, a large bearing surface or a plurality of separate bearing surfaces located along the connecting member with a large angular interval will impart a greater geometrical stability to the assembly. The bearing surface fastened to the outer end of the spiral spring is advantageously made in one piece with the spiral spring, particularly if the spiral spring is cut from a silicon plate, thus enabling a very high degree of precision to be achieved.
Advantageously, the respective bearing surfaces, which are at least partially complementary, of the connecting member and of the frame or of the member for the angular positioning of the regulating member on the frame include at least two elements for positioning the outer end of the spiral spring with respect to the axis of the balance wheel shaft and to the fixing of the inner end of the spiral spring on the balance wheel shaft, in order to position these ends as precisely as is permitted by the tolerances. Ideally, these positioning elements enable the initial shape of the spiral spring to be preserved in the resting position of the regulating member.
The attached drawings show, schematically and by way of example, various embodiments of the regulating member proposed by the invention.
In the variants of
As shown in
The variant in
Clearly, the annular connecting member 2 of
There are various possible solutions for fixing the connecting member 2 to the frame of the timepiece movement. The connecting member can be fixed directly to the balance bridge, or, advantageously, it can be fixed to the balance bridge by means of an intermediate part, mounted pivotably about the pivot axis of the balance wheel shaft, thus making it possible to set the reference position of the timepiece. The reference position is set by bringing the center of the impulse pin of the balance wheel on to the line linking the corresponding pivot centers of the balance wheel and the lever when the spiral-spring and balance wheel regulating member is in the equilibrium position.
The fixing points can be simple circular positioning holes 4 formed in the ring-shaped connecting member 2. In a variant, the positioning holes 4 of the connecting member 2 could incorporate flexible arms (not shown) for correct positioning, or could have an open profile in the form of a split tube having a degree of resilience, thus forming resilient arms to provide clamping around the pins 5.
The manufacturing tolerances of the spiral support 17 are greater than those of the spiral spring 1, and consequently the clearance at each fixing 17c can be adjusted to provide the most precise retention possible without overloading the system and making it statically indeterminate. A possible way of ensuring correct assembly is to leave a greater clearance at the intermediate fixing point 17c′, which then has a greater diameter than the others, in order to absorb the various errors due to the manufacturing tolerances on the other components. An alternative method is to specify the clearances of all the attachment points as a function of the tolerances of the rigid part.
The lower face of the spiral support 17 has a cut-out 17e to avoid friction with the spiral spring. The arms 17d of the support 17 act as a stop to prevent deformations of the spiral 1 under the effect of an impact.
A second embodiment is shown in
In this case there are not at least two separate fixing or stud points, but a fixing on a bearing surface extending over an arc of a circle of at least 60°. This solution provides simple reference position setting and facilitates the inspection and assembly operations. This is because there is no element covering the spiral spring, and all the turns of the spring remain visible.
In a third embodiment, resilient arms 2a separate two parts of the annular connecting member 2, thus enabling the annular connecting member 2 to be clipped, in the variant shown in
In a fourth embodiment, similar to the preceding one, resilient arms 2c are formed, in addition to or in place of the resilient arms 2e, in the edge of the annular connecting member 2 (
These different features, notably the different features of the different embodiments, and/or these different embodiments can be combined with each other provided that they are not incompatible.
Number | Date | Country | Kind |
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10405183 | Oct 2010 | EP | regional |
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3154912 | Pinkas | Nov 1964 | A |
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20050073913 | Born et al. | Apr 2005 | A1 |
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Number | Date | Country |
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1515200 | Mar 2005 | EP |
1918791 | May 2008 | EP |
2151722 | Feb 2010 | EP |
2006123095 | Nov 2006 | WO |
2010088891 | Aug 2010 | WO |
Entry |
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European Search Report (ESR) of European Appl. No. 10405183, dated Mar. 15, 2011. |
Number | Date | Country | |
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20120082010 A1 | Apr 2012 | US |