CH705112B1 - shock absorber bearing for a timepiece. - Google Patents

Abstract

The present invention relates to a shock absorbing bearing for a watch movement comprising: a pivot member (32) provided with a pierced stone (26) and intended to receive a pivot (18), and a counter-pivot stone (31), forming a support of said pivot (18), a fixing member and abutment (20, 22, 34) for mounting on a frame, an elastic member (29) connecting the pivot member (32) to the fixing member (20, 22, 34) and comprising at least one arm, characterized in that said elastic member (29) and one of the two stones (26, 31) of the pivot member (32) are consisting of a monolithic piece (24).

Description

Technical area

The present invention relates to a bearing for timepieces and more particularly of the type for damping shocks.

Such bearings are, most frequently, used to ensure the pivoting of the rockers. Indeed, these are provided with small diameter pivots, and therefore delicate. Since, moreover, the mass of the balance is relatively large, the risk is high that a pivot breaks under the effect of a shock.

The bearings intended to ensure the pivoting of a rocker generally comprise two stones, a pierced stone, in which is engaged a pivot of the balance and a stone against pivot, which serves as support and limitation to the axial displacement of the pivot. These stones are made of a nonmetallic hard material such as corundum.

State of the art

[0004] There are many types of shock absorbing bearings. The most frequently used include a body provided with positioning and sliding surfaces, a pierced stone and a counter-pivot stone together forming a pivot member, these stones being disposed in the body and positioned on the positioning and sliding surfaces. A spring maintains the stones in the rest position, while allowing them to move within a certain limit under the effect of a shock, the axis of the balance then arriving against stops. Such bearings have, for example, been sold under the trademark Incabloc <®>.

Also known shock absorbing bearings in which the elastic members and the pivot members form a whole. They have the advantage of being less expensive.

Thus, the document US 3,942,848 describes a shock absorbing bearing comprising an annular body intended to be driven in a bridge or a plate. A spring formed to define a conical housing is attached to the body. This housing is a truss inside which a conical pivot of the balance comes to engage. In such a construction, the pivoting conditions are unfavorable, metal-to-metal pivoting generating significant friction. Furthermore, a bearing type crapaudine cooperating with a conical pivot is poorly suited for a timepiece quality, the positioning of the balance is not very accurate.

EP 1 462 879 discloses shock absorbing bearings comprising a central part forming a pivot member and surrounded by a rosette formed in a plate of resilient rigid material. The rosette consists of springs extending radially, their central end cooperating with the central part. Such a solution makes it possible to take advantage of technologies implementing plates of constant thickness. In such a construction, the central piece must be put in place by removing the springs and the position is not obvious to guarantee. In addition, it results in a large footprint.

EP 1 696 286 discloses a shock absorbing bearing comprising a pivot member provided with a pierced stone and a counter-pivot stone. Said bearing also comprises a fixing member whose purpose is to ensure the mounting of the bearing on a frame. It further comprises an elastic member which connects the pivot member to the fastener. The pierced stone, the counter-pivot stone and the elastic member are three distinct elements. The bearing will therefore be relatively difficult to assemble.

Furthermore, the Swiss patent application CH 01 122/07, filed in the name of the applicant, describes a shock absorbing bearing comprising a pivot member and a resilient member formed in one piece in a pellet in a monocrystalline material, the pivot being engaged in a blind hole. Such a solution is very simple, but does not allow lubrication. This results in a risk of wear under certain pivoting conditions.

Disclosure of the invention

A main object of the present invention is to provide a simplified structure shock absorbing bearing which can be manufactured largely by photolithography processes associated with either etching processes or material growth processes, while allowing lubrication of the pivoting.

The shock absorbing bearing for a timepiece according to the invention comprises a pivot member provided with a pierced stone for receiving a pivot, and a counter-pivot stone forming a support of said pivot. It further comprises a fixing and abutment member for mounting on a frame and a resilient member connecting the pivot member to the fastener and comprising at least one arm. To achieve this goal said elastic member and one of the two stones of the pivot member together form a monolithic piece. The part is advantageously made of a monocrystalline material. Its manufacture is particularly well controlled when this material is silicon.

A flat surface is easier to achieve a curved surface, it is more interesting that the monolithic piece includes the stone against pivot.

In addition, cleaning holes in the counter-pivot stone facilitate the cleaning of the bearing, which is necessary if the latter is lubricated. These holes are offset with respect to the balance shaft.

To improve the fixation of the pierced stone on the monolithic part, it is rigidly attached to the monolithic part, preferably driven into a metal ring. The latter may be provided with two pins engaged in a hole made in said monolithic piece. These pins pass through said monolithic piece and are fixed thereto.

The bearing may, in addition, comprise a fastener provided with two holes arranged so as to each receive one of said pins, in which they are fixed.

These pins and the metal ring can be formed in one piece.

It is also possible to fix the pierced stone directly on the monolithic piece. In this case, the latter is provided with a core in which is housed and fixed said pierced stone, for example by means of glue.

In another embodiment, the monolithic piece has a two-level structure. The elastic member is formed of a first portion located at the first level with the counter-pivot stone and a second portion located at the second level, the pierced stone being integral with said second portion.

In a third embodiment, the bearing comprises a second monolithic part comprising a peripheral portion a central portion and an elastic member formed of arms connecting the peripheral portion to the central portion, said central portion having a hole in which is fixed said pierced stone.

Brief description of the drawings

Other features of the present invention will appear more clearly on reading the description which follows, made with reference to the accompanying drawings, in which: <tb> Figs. 1 and 2 <sep> represent a first variant, respectively seen in section and from above, of a first embodiment of the present invention; <tb> Fig. 3 <sep> shows a part intended to equip a bearing as shown in FIGS. 1 and 2; <tb> Fig. 4 <sep> is a sectional view of a second variant of the first embodiment; <tb> Figs. 5 and 6 <sep> show, in section, a third variant of the first embodiment; <tb> Figs. 7 and 8 <sep> illustrate a fourth variant of the first embodiment; <tb> Figs. 9 and 10 <sep> show, respectively seen in section and from above, a second embodiment, while FIGS. 11 and 12 are views in perspective, from above and below, of a part equipping the bearing of this embodiment; and <tb> Figs. 13 and 14 <sep> are sectional views of two variants of a third embodiment.

Embodiments of the invention

For the sake of clarity, the same elements have been designated by the same references in the different figures.

A first variant of a first embodiment of the invention is shown in FIGS. 1-3. More particularly, FIGS. 1and 2illustrate a portion of watch movement provided with bearings according to the invention, respectively seen in section and from above.

The movement comprises a frame comprising a plate 10 and a balance bridge 11, bearings 12 and 13 respectively mounted in holes 10a and 11a formed in the plate 10 and the bridge 11. These holes are coaxial, axis AA. A rocker 14 is pivotally mounted in the bearings 12 and 13. It comprises an axis 16 provided at its two ends with tigers 17, which carry pivots 18.

The bearing 12 comprises a fixing member comprising two annular pieces 20 and 22, the piece 22, cup-shaped, being pierced at its center with a hole 23, a monolithic piece 24 of monocrystalline material, and a stone 26. The piece 24, shown from above in perspective in Figure 3, has a round and flat shape. It comprises a central portion 27, a peripheral portion 28, of annular shape, and spirally wound arms, forming an elastic member 29, which connect the central portion 27 to the peripheral portion 28. The central portion 27, disc, is provided with a hole 27a in which is housed the pierced stone 26, fixed for example by gluing. The central portion 27 forms a counter-pivot stone 31 defined by the bottom of the core 27a. The counter-pivoting stone 31 constitutes, with the pierced stone 26, a pivoting member 32.

As the pierced stone 26 and the counter-pivot stone 31 form a whole difficult to dismantle, the portion of the central portion 27 forming the counter pivot stone 31 is provided with holes 33 offset relative to the axis AA, facilitating thus the cleaning of the bearing.

The monolithic piece 24 is interposed between the annular pieces 20 and 22. The piece 24, provided with the pierced stone 26, is disposed in the hole 10a of the plate 10, held radially by the wall of the hole 10a and axially by the annular parts 20 and 22. Such a structure makes it possible to adjust the axial position of the balance 14.

The monolithic piece 24 is made in a silicon wafer using the well known methods of photolithography and etching. The dimensions of this part 24 are advantageously included within the following limits: diameter 1.50 to 2.50 mm, typically 1.80 mm; thickness 0.20 to 0.30 mm typically 0.25 mm; arm thickness 0.04 to 0.08 mm typically 0.05 mm; angle covered by spiral arms 180 ° to 360 °, typically 270 °.

The bearing 13 comprises a fixing and abutment member 34 consisting of an annular cup-shaped part, which defines a housing having an inner cylindrical wall 36 and a flat bearing surface 37 in the bottom of the cup. . It is also pierced with a central hole 23. A truncated portion of cone 38 forms the free end of the cup. It retains and positions a mobile bolt carrier 40.

The bearing 13 also comprises a monolithic piece 24, provided with a pierced stone 26, in all respects similar to that fitted to the bearing 12. The piece 24, provided with the pierced stone 26, is fixed in the housing that form the cylindrical wall 36 and the flat bearing surface 37, advantageously by gluing. It could also be maintained axially similar to the bearing 12, by a ring driven on the cylindrical wall 36.

The rocker 14 is pivotally mounted by engagement of the pivots 18 in the hole of the pierced stones 26. The tigers 17 are engaged in the holes 23.

In case of side impact, the balance 14 is subjected to a force proportional to the acceleration. This force is transmitted to the bearings 12 and 13 via the pivots 18 which bear in the hole of the pierced stones 26. It has the effect of deforming the arms of the elastic member 29 until the axis 16 come to bear, by the rods 17, against the wall of the holes 23. The rocker 14 is then blocked by a portion of its axis which has dimensions much larger than those pivots 18. The structure is thus more robust.

In the event of an axial impact, one of the pivots 18 exerts a pressure on the counter-pivot stone 31, which has the effect of axially deforming the arms of the elastic member 29. The shaft 16 then bears against the adjacent flat wall surrounding the hole 23.

The arms of the elastic member 29 are dimensioned so that the axis 16 comes into contact, by the rods 17, with the annular piece 22 and the fastener and abutment member 34 when the acceleration reaches about 500 g, both for axial and radial impact.

Another variant of the first embodiment is shown in Figure 4. It includes the plate 10 and the pendulum bridge 11, the bearings 12 and 13 and the balance 14, with their component parts, which will not be described again here. In this variant, the pierced stone 26 is housed in a ring 42 of metal, for example brass or nickel-based alloy. The establishment of the stone 26 in the ring 42 is advantageously by driving. The assembly thus obtained can also be driven into the core 27a. If necessary, the stone 26 and the ring 42 can be removed or moved to ensure a suitable distance between the stone 26 and the pivot-pivot stone 31. This distance is important to ensure good resistance of the oil. This is, in fact, retained by capillarity between the stone 26 and the counter-pivot stone 31. If the distance is too small, the amount of trapped oil is low. If, on the contrary, this distance is too great, the trapped oil drop does not hold well in place is likely to be expelled during a shock.

In another variant, shown in Figures 5 and 6, there are the same parts as in that described above. However, it differs in two points, and more particularly in the structure of the bearing 12 which is housed in the plate 10, and the manner of associating the pierced stone 26 to the monolithic piece 24.

In this variant, the stone 26 is not included in the thickness of the monolithic piece 24, as is the case in the first variant. It is, on the contrary, interposed between the piece 24 and the annular piece 22, being fixed to the piece 24 by pins 43 engaged in holes in the ring 42 and in the central portion 27 of the monolithic piece 24. Advantageously, the pins 43 can be driven into the ring 42 and glued into the piece 24. Furthermore, the piece 24 is directly fixed by driving or gluing in the plate 10. The piece 22 thus no longer ensures the axial positioning of the bearing 12. It has more, for function, that to serve as a stop to the tigeron 17 as explained above.

It will be noted that the pins 43 are attached to the ring 42. It is obvious that they could also be manufactured in one piece with the ring 42, by machining, stamping or adding material.

The variant of FIGS. 7 and 8 differs from that of FIGS. 5 and 6 because the pins 43 protrude from the monolithic piece 24. A ring 44 of metal, for example brass or gold, also provided with holes, serves as a housing at the ends of the pins 43. More specifically, the pins 43 are driven into the holes in the ring 44. In this way, it serves as a fastener, now in place the stone 26 on the part 24. Furthermore, the ring 44 can be used to ensure an aesthetic function , to represent, for example, the logo of the watch as well as to ensure disassembly easier to achieve.

In the second embodiment, shown in FIGS. 9 to 12, the monolithic piece 24 comprises, as previously, a central portion 27 forming the pivot-pivot stone 31, and a peripheral portion 28. FIGS. 9 and 10 show a device according to this embodiment respectively seen in section and from above, and FIGS. 11 and 12 the monolithic pieces 24 views on both sides.

In this embodiment, the monolithic piece 24 has a two-level elastic orange with, at the first level, a first set of three arms forming a first elastic portion 45 connecting the peripheral portion 28 to the central portion 27, and at the second level, three arms forming a second elastic portion 46 secured to the peripheral portion 28 and enclosing the pierced stone 26. The latter can be fixed to the second elastic portion 46 by gluing. In other words, the first elastic portion 45 and the central portion 27 occupy a first level, the second elastic portion 46 and the stone 26 a second level, and the peripheral portion 28 occupies both levels.

To be able to manufacture such a structure by photolithographic techniques, it is necessary that the constituent parts of one of the levels do not overlap with those of the other level. In order to make this requirement very apparent in these figures, the arms of the first and second resilient portions 45 and 46 have a meander structure. They could however also have a spiral shape.

The manufacture of the part 24 is done, as previously by photolithography and etching techniques. In a first step, a mask is placed on one of the faces of the plate in which the monolithic pieces are made, and this face is chemically etched on a little more than half the thickness. In this step, the shapes of the constituent parts of the first level are defined. During the second step, the piece is turned over and a mask is arranged to define the structure of the second level. The plate is, here too, attacked on a little more than half of the thickness. In this way, the two levels are perfectly defined and independent. Then, the monolithic pieces 24 are extracted from the base plate by attacking the periphery over the entire thickness.

In this embodiment, the monolithic parts 24 are fixed to the frame of the movement identically to the variant shown in Figs. 1 and 2.

With this variant, the forces generated by an action of the axis of the balance 14 on the pierced stone 26 or on the counter pivot stone 31 can be dimensioned independently.

A third embodiment is shown, according to two variants, in FIGS. 13 and 14. In the variant of FIG. 13, the device comprises, in addition to the monolithic pieces 24, second monolithic pieces 47.

The parts 24 have a constant thickness. They each comprise the peripheral portion 28, the central portion 27 forming the counter pivot stone 31, and arms forming the elastic member 29. The pierced stones 26 are each fixed to one of the monolithic pieces 47. The latter comprise also a peripheral portion 48, a central portion 49 and an additional elastic member 51 formed of arms connecting the peripheral portion 48 to the central portion 49, which is pierced at its center, to form a hole 52 in which the pierced stone 26 is fixed for example by gluing.

This solution also allows to have independent elastic members with different characteristics to cooperate on the one hand with the stone 26, on the other hand with the stone against pivot 31.

The annular piece 22 and the fixing and abutment member 34 are each provided with two bearing surfaces 53 and 54, on which the monolithic parts 24 and 47 are respectively supported and fixed, for example by means of glue points. . The annular piece 22 and the fixing and abutment member 34 are themselves respectively driven into the plate 10 and the bridge 11.

In the variant illustrated in FIG. 14, the monolithic parts 24 and 47 are substantially thicker than in the variant of FIG. 13. The monolithic piece 47 is provided with a recess 55 in which is fixed the pierced stone 26. This core 55 is pierced with a central hole 56 and side holes 57, one of which is visible in the drawing. The holes 57 serve to facilitate cleaning, such as the holes 33 described with reference to FIGS. 1 to 3.

The monolithic piece 24 is provided with a central stud 58 engaged in the hole 56, with a slight clearance. The end of the stud 58 provides the stone counter pivot function 31.

The fixing of the monolithic parts 24 and 47 is done in the same way as in the variant shown in FIG. 13.

The behavior of this device during axial shocks is the same as for the embodiments described above. This is not the case during radial shocks. With this structure, as long as the shocks are weak, only the additional elastic member 51 is biased. If the shock is greater, the wall of the hole 56 bears against the stud 58, so that the elastic member 29 is also biased.

The bearings described above may be the subject of many other embodiments or variants, without departing from the scope of the invention defined in the claims. It will be noted in particular that the monolithic parts may be made of silicon or another preferably monocrystalline material easily machinable by photolithography and chemical etching techniques. These parts may, in addition, undergo surface treatments, for example be coated with a diamond layer or be oxidized.

It is also possible to produce them in a polycrystalline material, for example by growth.

The various embodiments described above thus make it possible to achieve efficient and compact shock-absorbing bearings that are simple in their structure and can be lubricated in good conditions.

Claims (14)

Shock absorbing bearing for a watch movement comprising: - a pivot member (32) provided with a pierced stone (26) and intended to receive a pivot (18), and a counter-pivot stone (31) forming a support of said pivot (18), A fixing and abutment member (20, 22, 34) intended to ensure its mounting on a frame, An elastic member (29) connecting the pivoting member (32) to the fixing member (20, 22, 34) and comprising at least one arm, characterized in that said elastic member (29) and one of the two stones (26, 31) of the pivot member (32) together form a monolithic piece (24). 2. Bearing according to claim 1, characterized in that the monolithic piece is made of a monocrystalline material. 3. Bearing according to claim 2, characterized in that the monocrystalline material is silicon. 4. Bearing according to claim 1, characterized in that said monolithic piece (24) comprises said counter pivot stone (31). 5. Bearing according to claim 4, characterized in that the counter-pivot stone (31) is provided with at least one hole (33) offset from the axis of the pivot member. 6. Bearing according to claim 4, characterized in that said pierced stone (26) is rigidly attached to said monolithic piece (24). 7. Bearing according to claim 6, characterized in that said pierced stone (26) is driven into a metal ring (42). 8. Bearing according to claim 7, characterized in that said ring (42) is provided with two pins (43) engaged in a hole in said monolithic piece (24). 9. Bearing according to claim 8, characterized in that said pins (43) pass through said monolithic piece (24) and are fixed thereto. 10. Bearing according to claim 8, characterized in that it further comprises a fastener (44) provided with two holes arranged so as to each receive one of said pins (43), in which they are fixed. 11. Bearing according to claim 8, characterized in that said pins (43) and said ring (42) are formed in one piece. 12. Bearing according to one of claims 6 or 7, characterized in that said monolithic piece (24) is provided with a recess (27a) in which is glued said pierced stone (26). 13. Bearing according to one of claims 1 to 3, characterized in that said monolithic piece (24) has a two-level structure, said elastic member being formed of a first elastic portion (45) located at the first level with the counter-pivot stone (31) and a second elastic portion (46) located at the second level, the pierced stone (26) being integral with said second elastic portion (46). 14. Bearing according to one of claims 1 to 3, characterized in that it comprises a second monolithic part (47) having a peripheral portion (48) a central portion (49) and an additional elastic member (51) formed of arm connecting the peripheral portion to the central portion, said central portion having a hole (52) in which is fixed said pierced stone (26).