CH714250A1 - Oscillator for watch movement. - Google Patents

Abstract

The present invention relates to an oscillator (1) for a watch movement comprising a balance shaft (6) rotatably mounted in a balance bridge (22) intended to be assembled to a frame element of the watch movement, a balance (2) and a ferrule (8) integral with the balance shaft (6), characterized in that the ferrule (8) is interposed between the balance (2) and the balance shaft (6) to ensure the mounting of the balance (2 ) on the balance shaft (6).

Description

Description

TECHNICAL FIELD [0001] The present invention relates to an oscillator for a watch movement comprising a balance shaft rotatably mounted in a balance bridge intended to be assembled to a frame element of the watch movement, a balance and a ferrule integral with the axis of balance.

The invention also relates to a watch movement comprising such an oscillator and a timepiece comprising such a watch movement.

STATE OF THE ART [0003] Many timepieces comprising an oscillator meeting the above characteristics have been known for a long time.

[0004] Patent application CH 707 226 A2 describes and illustrates a recent example of a compact construction of an oscillator of this type. This oscillator comprises a balance shaft carrying a balance and a ferrule, ensuring the attachment of the inner end of a spiral, and a double plate made in one piece and frictionally engaged on the balance shaft. Furthermore, the balance shaft comprises directly on its surface a raceway to define the inner ring of a ball bearing or roller. This bearing comprises an outer ring having two ears to ensure its assembly on a bridge to be assembled to a frame member of a watch movement. This bridge at the same time performs the role of anchor bridge since it carries a stone in which the anchor rod is rotated. This construction therefore has a relatively small footprint, particularly in the direction of its thickness, and no bridge comes to cover the sprung-balance which gives it an airy appearance. Only a bolt carrier extends partially above the balance-balance to ensure the attachment of the outer end of the spiral, the bolt carrier being assembled to the platen of the watch movement.

The construction illustrated in this patent application has a size in the axial direction such that it seems difficult to reduce it further. Indeed, the balance and the spiral are adjacent to each other and it is preferable to maintain a minimum distance between them to limit the risk of collision, especially in case of shock applied to the corresponding timepiece.

However, in general, there are still many reasons to urge the watch manufacturer to reduce the clutter of some watch mechanisms, including to save space for other mechanisms, for example complications or barrels to increase the power reserve, or simply to reduce the thickness of the watch movement to allow it to be integrated in a watch ultra-thin and / or women.

Disclosure of the invention [0007] A main object of the present invention is to propose an oscillator construction for a watch movement of the type mentioned above, having a reduced bulk with reference to the known constructions, without the congestion gain being at the expense of simplicity of assembly, a good reliability of operation or even possibilities of adjusting the parameters of the oscillator.

For this purpose, the present invention relates more particularly to an oscillator for a watch movement corresponding to the aforementioned characteristics, characterized in that the ferrule is interposed between the balance and the balance shaft to ensure the mounting of the balance on the balance shaft.

Thanks to these characteristics, the gap between the balance and the hairspring is perfectly controlled, by manufacture of the shell, and these two components can be arranged with a minimum of distance between them, thus reducing the thickness of the oscillator. Moreover, these characteristics may possibly slightly simplify the realization of the balance shaft which must typically have a shoulder defining a stop during the implementation of the balance. Such a shoulder can however be maintained to ensure the establishment of the ferrule on the balance shaft. In addition, the risk of breakage of the balance shaft during assembly of the oscillator, particularly when made of a brittle material such as ceramic, is reduced since there is more than a component to hunt on it, the shell, instead of two in a conventional construction, namely the shell and the pendulum.

Preferably, the ferrule has a substantially cylindrical barrel arranged to define a bearing surface for the beam and defined in its axial direction by at least one shoulder defining an axial stop for the beam.

In this case, it can advantageously be provided that the ferrule comprises at least three, preferably four, shoulders defining axial stops for the balance, at least a portion of the shoulders being also intended to provide guidance of a first internal turn of a spiral.

According to a preferred embodiment, the ferrule is arranged on the balance shaft such that the shoulder or are located between the balance bridge and the barrel.

With these features, the spiral may possibly be partially housed in the thickness of the beam to further reduce the thickness of the oscillator according to the invention. In addition, this allows to accommodate a bolt to lock the outer coil of the spiral side bridges and not over the oscillator as is the case of the previous construction mentioned above.

According to a preferred embodiment, the pendulum bridge may have a bore defining an outer ring of a bearing, ball or roller, cooperating with an inner ring of the bearing integral with the balance shaft .

In this case, it is advantageous to provide a raceway is formed directly to the surface of the balance shaft to define at least a portion of the inner ring.

In general, it is also possible that the balance shaft carries a double plate made of a piece with him.

Note that in the case of a balance shaft mounted on a bearing and forming part of the bearing, it is even more interesting to limit the number of operations to be performed on the axis, as in the case of a conventional axis, since such an axis is more fragile and costs more to manufacture, which implies a higher loss in case of breakage. That is why it is advantageous, in the context of the invention, to have a single driving instead of traditionally a riveting (balance on axis) and a driving (ferrule on axis).

According to other additional preferred features of the present invention, it can be provided, when the oscillator comprises a stud designed to cooperate with an outer coil of a spiral, the balance bridge bearing a bearing housing the axis of balance, the oscillator further comprises a support having a curved slot, of substantially constant radius of curvature and arranged concentrically to the bearing, the stud being housed in the curved slot being able to occupy different positions according to the length of the latter to adjust the mark.

In this case, it can be provided that the oscillator comprises a locking device capable of switching, on demand and in one direction or the other, between a first active state, in which it acts on the peak for locking it in a given position, and a second inactive state, in which it leaves the pin free to be moved along the length of the curved slot.

The support can then advantageously be an anchor bridge having an indexed position with reference to the balance bridge.

The present invention also relates to a watch movement comprising an oscillator that meets the characteristics that have just been exhibited, as well as a timepiece comprising such a watch movement.

BRIEF DESCRIPTION OF THE DRAWINGS [0022] Other features and advantages of the present invention will become more apparent upon reading the detailed description of a preferred embodiment which follows, with reference to the accompanying drawings given by way of non-limiting examples. in which: FIG. 1 is a simplified and exploded perspective view of a portion of an oscillator for clock movement according to a preferred embodiment of the invention; fig. 2a is a simplified perspective view of the components illustrated in FIG. 1 when assembled; fig. 2b is a view similar to the view of FIG. 2a when the oscillator according to the preferred embodiment of the invention is shown cut in the middle, along a cutting plane parallel to the plane of the sheet, and FIGS. 3a, 3b, 3c show the same view of a part of a watch movement at successive stages of assembly of the oscillator according to the preferred embodiment of the invention.

Embodiment (s) of the Invention [0023] FIG. 1 shows a simplified and exploded perspective view of a portion of an oscillator 1 for a watch movement according to a preferred embodiment of the invention. Figs. 2a and 2b show perspective views of the oscillator 1 when assembled, the assembly being fully illustrated in FIG. 2a and in section in FIG. 2b to make some construction details apparent.

In general, only the elements necessary for a good understanding of the invention have been illustrated for the sake of clarity and conciseness.

The oscillator 1 is of the sprung-balance type. It comprises a balance 2, adjusting screw, and a spiral 4, interacting with each other in a conventional manner.

The rocker 2 and the spiral 4 are intended to be assembled to a rocker shaft 6 by means of a shell 8, engaged frictionally on the balance shaft 6 in a known manner. The ferrule acts as a first locking member of a first end, internal, spiral 4, in a conventional manner.

[0027] It is more particularly apparent from FIG. 2a, but especially of fig. 2b, that the ferrule 8 here plays a particular role compared to known constructions: it is engaged on the balance shaft 6 in a conventional manner, but the rocker 2 is engaged on it rather than being positioned in support against a shoulder of the balance shaft 6 as is generally the case. This construction makes it possible to limit the stresses applied to the balance shaft 6 which could break otherwise, depending on the material in which it is made, for example ceramic. In addition, this construction also reduces the size of the oscillator in the direction of its thickness, the balance 2 and the spiral 4 being located very close to one another.

Note that, according to the present preferred embodiment illustrated and described here as a non-limiting indication, the shell 8 comprises a barrel 7 substantially cylindrical, arranged to define a bearing surface for the balance 2 and defined, following its axial direction, by four shoulders 9 defining axial stops for the balance 2 when it is adjusted, centered and then riveted on the shell 8. It is further noted that the shell 8 is arranged in such a way that the rocker 2 is located substantially at the free end of the balance shaft 6, the spiral 4 is thus located on the side of the watch movement, as is more particularly apparent from FIGS. 2a and 2b.

The balance shaft 6 here fulfills several additional functions, advantageously and preferred but not absolutely necessary for the implementation of the present invention. More specifically, a conventional double plate 10, 12 is made in one piece with the rocker shaft 6. The large plate 10 is pierced with a hole 14, axial, for receiving a plate pin 16 (in FIG. 2b) for cooperating with an anchor of an escapement.

Furthermore, a raceway 18 is formed directly on the surface of the balance shaft 6 so that the latter can play the role of at least one inner ring portion of a ball bearing or rollers .

The rocker shaft 6 is then intended to be engaged in the central bore 20 of a rocker bridge 22 defining an outer ring of the bearing, the central bore 20 acting as a bearing for the balance shaft 6.

A ring 24 defining an additional annular bearing surface of the bearing is secured to the balance shaft 6 after insertion of the balls 26 to maintain the latter captive in the bearing thus closed.

Furthermore, the rocker bridge 22 is here directly associated with an anchor bridge 28 also having a central bore 30 defining a housing for the double plate 10, 12 of the balance shaft 6 and to allow it by subsequently to cooperate with the anchor, as will be apparent more particularly from Figs. 3a to 3c.

Note that, preferably in a nonlimiting manner, the rocker bridge 22 has two holes 32 intended to be aligned with two holes 34 of the anchor bridge 28, for purposes of indexing these two bridges, like this. will also emerge from fig. 3a to 3c.

Similarly, the rocker bridge 22 has three additional holes 36 intended to be aligned with three corresponding recesses 38 of the anchor bridge 28, to allow the assembly of the oscillator on the plate of a watch movement. as will also be apparent from FIGS. 3a to 3c.

Finally, the anchor bridge 28 has two additional substantially diametrically opposed functional areas, by way of nonlimiting illustration.

On the one hand, the anchor bridge 28 comprises an elevated portion 40 housing a stone 42 for receiving the anchor rod.

On the other hand, the anchor bridge 28 comprises a portion 44 having an extra thickness with reference to the average thickness of the bridge. A slot 46 passing through the portion 44 along its thickness is formed in the anchor bridge 28 to define a housing for a second locking member of the second, outer end of the spiral 4, here a pin 48.

The slot 46 is curved, with a substantially constant radius of curvature, and is arranged concentrically with the central bore 30 of the anchor bridge 28, so that it is concentric with the central bore 20 of the bridge of balance 22 and that its center of curvature is, therefore, located on the pivot axis of the balance shaft 6.

The peak 48 has a bearing 50 whose transverse dimensions are greater than the width of the slot 46 to define a stop in the axial direction. The span 50 is surmounted by a barrel 52 advantageously having two flats 53 opposite to cooperate with the walls of the slot 46 to provide a guide of the stud 48 along the length of the slot 46, when adjusting the mark. The barrel 52 is itself surmounted by a clamp 54 for locking the conventional spiral, intended to cooperate with the end turn of the spiral 4, typically by gluing. Thus, any displacement of the stud 48 along the length of the slot 46 has the effect of moving the outer end of the spiral 4 with reference to its inner end, which allows to adjust the reference of the oscillator, that is to say to say to ensure that the oscillations of the balance 2 on either side of its rest position are symmetrical.

A locking device is provided to lock the stud 48 in the position corresponding to the setting of the marker to fix it. This locking device comprises a plate 56 intended to be positioned substantially facing the slot 46 and bearing against the bearing 50 of the stud 48 to press against the anchor bridge 28 and immobilize the stud 48. The assembly of the plate 56 to the anchor bridge 28 is here made by means of two screws 58.

Thus, it is understood that, starting from a given position of the stud 48 in the slot 46, the watchmaker wishing to make an adjustment of the mark must loosen the two screws 58 to separate the wafer 56 from the anchor bridge 28 and release the piton 48 which can then be moved to a new position. The two screws 58 can then be tightened to bring the wafer 56 closer to the anchor bridge 28 and ensure that the bearing 50 of the stud 48 is veneered against the anchor bridge 28, thus ensuring the locking of the stud 48.

Of course, the forms illustrated and described for the stud 48 and the locking device are as a non-limiting example and the skilled person will not encounter any particular difficulty to adapt them according to his own needs .

By way of additional example, it may be provided that the scope of the stud is located between the barrel and the clamp, so as to rest on the upper plane of the anchor bridge in the orientation of FIG. 1. The barrel could then be provided with a tapped central hole with which a span screw could cooperate in such a manner that, when this screw was tightened, in a bottom-up movement in the view of FIG. 1, the anchor bridge would be caught in a vice between it and the reach of the bolt, thus ensuring a locking of the latter.

Figs. 3a, 3b and 3c represent, in a same simplified perspective view, successive steps of assembling the oscillator 1 which has just been described on a watch movement.

The plate 60 of the watch movement is shown but will not be described in detail, since it comprises various particular recesses having no connection with the implementation of the present invention.

The plate 60 comprises a double recess 62 whose left part in FIG. 3a is intended to receive the oscillator 1 and the right portion is in particular for receiving the escape wheel (not shown). The plate comprises a stone 64 located substantially at the boundary between the two parts of the recess 62 and in which is housed the rod 66 of the anchor 68.

The recess 62 has a complex shape substantially complementary to that of the oscillator 1, in particular with different regions of different depths.

A first small recess 70 is formed in the region around the fork and the stinger of the anchor 68, this recess 70 being intended to accommodate the small plate 12 of the balance shaft 6, which is intended to cooperate with the stinger of the anchor 68. The pin 16 driven into the large plate 10 is in turn intended to cooperate with the fork of the anchor 68, in a conventional manner.

A second small recess 72 has a shape similar to that of the portion 44 of the anchor bridge 28 having an extra thickness, that is to say the portion in which the slot 46 is formed to accommodate the stud 48.

Furthermore, two feet 74 extend from the bottom of the recess 62, and three pillars 76 threaded for receiving screws.

Passing from FIG. 3a in FIG. 3b, it can be seen that the anchor bridge 28 has been put in place on the plate 60, its holes 34 being engaged on the feet 74, the pillars 76 then being situated in the recesses 38 of the anchor bridge 28.

It is also seen in FIG. 3b that the elevated portion 40 of the anchor bridge 28 defines a passage for the anchor 68.

In addition, the central bore 30 of the anchor bridge 28 has two projecting portions 78 defining starlets for the anchor 68.

[0055] Turning to FIG. 3c, it is found that the remaining components are preassembled on the balance bridge 22 before it is placed on the anchor bridge 28. On the one hand, the bearing is formed by assembly of the balance shaft 6 to the balance bridge 22, with insertion of the balls 26 and closure of the bearing with the ring 24. On the other hand, the spiral 4 and the balance 2 are assembled to the shell 8, before the latter is engaged by force on the balance shaft 6.

The assembly thus assembled is then approached to the plate 60, the holes 32 of the rocker bridge 22 being aligned with the feet 74 so as to engage the latter in the holes 32.

Three screws 80 are then screwed into the pillars 76 to secure the oscillator 1 to the plate 60.

With the characteristics just described, it is possible to realize an oscillator construction of limited size and complexity, whose assembly is very simple and still offers the possibility of making a precise adjustment its chronometric properties since its landmark can be adjusted.

The foregoing description attempts to describe a particular embodiment by way of non-limiting illustration and, the invention is not limited to the implementation of certain particular features which have just been described, as for example the forms illustrated and described for the pendulum and anchor bridges, the bolt and for its locking device, as well as for the balance shaft and the ferrule. Thus, for example, as noted above, the ferrule could have a different number of shoulders, for example at least three, to define stops for the pendulum, without departing from the scope of the invention. Those skilled in the art will not encounter any particular difficulty in adapting the content of the present disclosure to their own needs, and implement an oscillator for a watch movement comprising a balance-spring in which both the hairspring and the pendulum are assembled to a balance shaft through the same ferrule, without departing from the scope of the invention.

Claims (12)

claims Oscillator (1) for a watch movement comprising a balance shaft (6) rotatably mounted in a balance bridge (22) intended to be assembled to a frame member (60) of the watch movement, a balance (2) and a ferrule (8) integral with said balance shaft (6), characterized in that said ferrule (8) is interposed between said rocker (2) and said rocker shaft (6) for mounting said rocker (2) on said axis balance wheel (6). 2. Oscillator (1) according to claim 1, characterized in that said shell (8) has a barrel (7) substantially cylindrical arranged to define a bearing surface for said beam (2) and delimited in its axial direction by a at least one shoulder (9) defining an axial stop for said beam (2). 3. Oscillator (1) according to claim 2, characterized in that said shell (8) comprises at least three, preferably four, shoulders (9) defining axial stops for said beam (2), at least a portion of said shoulder- elements (9) also being intended to guiding a first internal turn of a spiral (4). 4. Oscillator (1) according to claim 2 or 3, characterized in that said ferrule (8) is arranged on said balance shaft (6) such that said shoulder or (s) (9) are located between said balance bridge (22) and said barrel (7). 5. Oscillator (1) according to one of the preceding claims, characterized in that said balance bridge (22) has a bore (20) defining an outer ring of a bearing, ball or roller cooperating with a ring internal of said bearing secured to said balance shaft (6). 6. Oscillator (1) according to claim 5, characterized in that a raceway (18) is provided directly on the surface of said balance shaft (6) to define at least a portion of said inner ring. 7. Oscillator (1) according to one of the preceding claims, characterized in that said balance shaft (6) carries a double plate (10, 12) formed integrally with it. 8. Oscillator (1) according to one of the preceding claims, comprising a stud (48) for cooperating with an outer coil of a spiral (4), said balance bridge (22) bearing a bearing (20) housing said balance shaft (6), characterized in that it comprises a support having a curved slot (46) of substantially constant radius of curvature and arranged concentrically with said bearing (20), said pin (48) being housed in said curved slot (46) being able to occupy different positions along the length of the latter to adjust the marker. 9. Oscillator (1) according to claim 8, characterized in that it comprises a locking device (56, 58) capable of switching, on demand and in one direction or the other, between a first active state, wherein it acts on said pin (48) to lock it in a given position, and a second inactive state, wherein it allows said pin (48) free to be moved along the length of said curved slot (46). 10. Oscillator (1) according to claim 8 or 9, characterized in that said support is an anchor bridge (28) having a position indexed with reference to said balance bridge (22). 11. Watch movement comprising an oscillator (1) according to one of the preceding claims. 12. Timepiece comprising a watch movement according to claim 11.