CH712862B1 - Shock-absorbing bearing for a timepiece. - Google Patents

Abstract

The present invention relates to a shock-absorbing bearing for a rod of an axis of a mobile of a timepiece comprising a support block (1) intended to be driven, fixed or formed in the frame of said timepiece. watchmaking, said support block (1) being provided with a housing designed to receive an axially deformable spring (12) and a bezel supporting a pierced stone through which the shank passes and a counter-pivot stone (5), the spring (12 ) being arranged in the housing between the bezel and at least one projecting portion of a peripheral rim of the support block, characterized in that the spring (12) is formed by a peripheral ring from which extend at least one extension (13) provided with a support head in contact with the counter-pivot stone, this support head having the shape of an arc of a circle whose interface with the extension is via its convex face.

Description

TECHNICAL AREA

The present invention relates to a shock-absorbing bearing for a timepiece, and more particularly the bearing of the balance shaft of a mechanical watch, making it possible to avoid the breakage of the small-diameter pivot, located at its extremity, designated by "tigeron", in the event of an axial or lateral impact, which may simply result from a sudden movement of the wearer's wrist.

TECHNOLOGICAL BACKGROUND

[0002] Manufacturers of mechanical watches have long designed numerous devices making it possible to absorb the energy resulting from an impact, in particular from a side impact, by the axis by abutting against a wall of the hole in the block of base it crosses, while allowing a momentary displacement of the shank before it is returned to its rest position under the action of a spring.

Figures 1 to 3 illustrate a device, called "inverted double cone" which is currently used in timepieces on the market. A device of this type is for example described in patent FR 1 532 798.

A support block 1, the base of which has a hole 2 for the passage of the balance shaft 3 terminated by a shank 3a, makes it possible to position a bezel 20 in which are immobilized a pierced stone 4 crossed by the shank 3a and a counter-pivot stone 5. The bezel 20 is held in a housing 6 of the support block 1 by a spring 10 which in this example comprises radial extensions 9 compressing the counter-pivot stone 5. The housing 6 has two bearing surfaces 7, 7a in the form of inverted cones on which rest additional bearing surfaces 8, 8a of the bezel 20, said bearing surfaces having to be executed with very high precision. In the event of an axial shock, the spring 10 acts alone to return the balance shaft 3 to its initial position. In the event of a side impact, that is to say when the end of the shank unbalances the bezel 20 outside its plane of rest, the spring 10 cooperates with the complementary inclined planes 7, 7a; 8, 8a to refocus the bezel 20. The support block 1 comprises a peripheral rim 11 in which two diametrically opposed openings 11a are made.

The current spring is a substantially flat lyre spring 10. Such a spring comprises a base from which two arms extend. These curved arms are symmetrical and extend to give a lyre shape. Ideally, the arms are arranged to form two parts of the same circle, the center of which is the center of the lyre spring. Each arm comprises, at its free end, a hook making it possible to rest on projecting portions 11b of the rim extending at the level of the openings.

[0006] The radial extensions 9 of the spring extend from the inside of the arms.

In a variant visible in Figure 3, each arm of the spring is arranged to be bent to form an extension. The extension has the shape of an arc of a circle whose interface with the extension is via the concave face of said support head 14.

[0008] This configuration has the disadvantage of having only one point of support per arm in all circumstances. This point of contact is located in the stiffest part of the extension. This thus causes an imperfect spring response. Indeed, during a weak impact, having a fulcrum in the most rigid part may cause energy to be absorbed by the shank, whereas in the event of significant impact, no progressiveness will be present.

SUMMARY OF THE INVENTION

The present invention therefore aims to overcome the drawbacks of the aforementioned prior art by providing a shock-absorbing bearing comprising a pierced stone and a counter-pivot stone assembled in a bezel suspended by a lyre spring allowing a more progressive response to shocks.

[0010] To this end, the subject of the invention is a shock-absorbing bearing for a shank of an axis of a moving part of a timepiece comprising a support block intended to be driven out, fixed or formed in the frame. of said timepiece, said support block being provided with a housing designed to receive an axial deformation spring and a bezel supporting a pierced stone through which the shank passes and a counter-pivot stone, the spring being arranged in the housing between the bezel and at least one projecting portion of a peripheral rim of the support block, characterized in that the spring is formed by a peripheral ring from which extend at least one extension provided with a bearing head in contact with the counter-pivot stone, this support head having the shape of an arc of a circle whose interface with the extension is via its convex face.

In a first embodiment, said spring comprises two arms in the form of an arc of a circle connected to each other via a crosspiece and having two free ends each comprising a support zone, said at least one extension extending from one of the two arms.

In a second embodiment, said support head has a curvature greater than that of the arms.

[0013] In a third embodiment, said spring is formed of a curved band in order to produce internal radial extensions arranged between annular parts, said internal radial extensions bearing the bearing heads.

[0014] In a fourth embodiment, the spring comprises two diametrically opposed extensions.

[0015] In a fifth embodiment, the spring comprises three extensions.

[0016] In a sixth embodiment, the three extensions are regularly distributed.

BRIEF DESCRIPTION OF THE DRAWINGS

Other characteristics and advantages of the present invention will appear more clearly in the following description of an exemplary embodiment given by way of non-limiting illustration with reference to the appended drawings in which: Figures 1 to 2 show in perspective a shock-absorbing bearing according to the prior art; Figure 3 shows a shock absorber bearing spring according to the prior art; FIGS. 4 to 6 correspond to a shock-absorbing bearing and its spring according to a first embodiment of the invention; Figure 7 is an alternative embodiment of the spring visible in Figure 6; Figure 8 is another embodiment of the spring visible in Figure 6; FIG. 9 represents a second embodiment of a spring according to the invention

DETAILED DESCRIPTION OF THE INVENTION

Referring essentially to Figures 4 and 5, there is described below a shock absorber bearing 100 according to the invention intended to prevent the breakage or the decentering of the shank 202 of a balance shaft 200 of a piece of watchmaking. The identical or similar construction elements to those of the prior art illustrated in the preamble by Figures 1 and 2 will be designated by the same references.

The bearing comprises a support block 1 of circular shape delimiting a housing 6 whose center is pierced with a hole 2 to allow the passage of a balance shaft 200 terminated by a shank 202.

[0020] The support block 1 can be either an independent part driven out or fixed by any other means in the frame of the watch movement, or be part of another part of the movement, such as a bridge or a plate.

As can be seen, the kitten 20 which supports the pierced stone 4 crossed by the shank 3a and the counter-pivot stone 5 is damped by a spring 12.

[0022] Indeed, the support block 1 comprises a peripheral flange 9 comprising two openings 10. These openings 10 are diametrically opposed and allowing the establishment of the spring 12. Indeed, the peripheral flange 9 comprises protruding portions 11 s' extending to the level of the openings. More precisely, the two openings 10 making it possible to have a peripheral rim 9 in two identical parts. Each part comprises, at each end, a projecting portion 11 extending towards the center of the opening. These protruding portions 11 allow the spring 12 to bear against them. Spring 12 is a ring-shaped spring.

In a first embodiment visible in Figure 6, the spring 12 is a lyre spring. Such a spring 12 consists of two arms 12a in the form of an arc of a circle connected together, via a crosspiece 12b, at one of their ends, the whole forming a form of peripheral ring 12'. This spring 12 thus has two free ends each comprising a support zone 12c. Such a support zone 12c can take the form of a curvature of each arm at its free end in order to widen the zone.

This configuration of the spring allows it to be installed in the housing 6 of the support block. Indeed, once the bezel 20 is in place, the spring 12 is installed. The spring 12 is installed so as to press the bezel into the housing while having the crosspiece 12b and the support zones 12c pressed against the projecting portions 11 of the peripheral rim.

To cushion the bezel during a shock, the spring 12 comprises at least one extension 13. This extension 13 extends from one of the arms 12a of the spring towards its center. This extension made of material with the spring 12 is used to exert a preload on the counter-pivot stone and to bring the bezel back into the housing during an impact.

[0026] The spring 12 is dimensioned so that only the extension is in contact with the counter-pivot stone. Similarly, the arms 12a in the form of an arc of a circle are formed to have the same center and substantially form a circle with center C. This center C also becomes the center of the spring.

Cleverly according to the invention, the extension comprises, at its free end, a support head 14 made of material with the extension. This support head 14 has the shape of an arc of a circle whose interface with the extension 13 is made via the convex face of said arc of a circle. Each support head has the shape of an arc of a circle having a greater curvature than that of the arms forming the spring. The radius of the arc of a circle forming the bearing head is therefore greater than if this arc of a circle had a radius whose center el was the center C of the spring. It is therefore understood that the center C 'of the arc of a circle of each arm is offset with the center C of the spring as shown in Figure 7. The extension with its support head 14 therefore has a shape similar to a T .

This design provides an extension 13 in the form of a tee whose arms have better contact with the stone against pivot. The bearing head 14 of the extension 13 advantageously has a reverse curvature with respect to that of the prior art described above. This makes it possible to force contact with the "counter-pivot" stone in the extremities since the support head has a shape tending to match the shape of the counter-pivot stone.

[0029] An advantage of this configuration is to have several contact points. Indeed, the shape of the support head 14 allows it to be, at rest, in contact with the counter-pivot stone 5 in two places E1 and E2. This increase in the number of contact points makes it possible to have better stability of the support on the counter-pivot stone 5.

[0030] During a shock, the bezel 20 is moved by the axis and its shank. This movement of the kitten 20 is damped by the spring 12. This spring 12 under the effect of the stress exerted by the kitten 20, deforms. In the case of the spring 12 according to the invention, the deformation following a shock has the effect of shifting the contact points E1, E2. These contact points E1, E2 thus tend to approach the center of the bearing head 14. This offset of the contact points E1, E2 is due to the specific shape of the bearing head.

However, the central zone of the bearing head 14 is the most rigid part so that the deformation of this part 14 is less easy. Consequently, the greater the impact, the greater the contact between the extension 13 of the spring 12 and the counter-pivot stone 5 on the most rigid zone of said extension. This makes it possible to obtain better damping during major shocks.

[0032] This configuration of spring 12 also makes it possible to have a better view of the lubricant. In a bezel 20 as described, the lubricant is arranged between the pierced stone and the counter-pivot stone. With the configuration of the extension 13 and in particular of the support head, the view of the center of the counter-pivot stone is released and defined. This is possible due to the shape of the support head or heads which tend to delimit a zone. With a circular arc shape whose interface with the extension is via the concave face, the spring extensions must be longer and the support heads offer a visual that does not delimit any zone and obstruct the view of the lubricant.

In a variant visible in Figure 7, it will be possible to have a spring 12 provided with two extensions 13, these extensions being arranged ideally diametrically opposite.

In another variant visible in Figure 8, it will be possible to have a spring 12 provided with three extensions 13, these extensions being arranged so as to be angularly distributed. The spring 12 thus comprises 3 arms 12a. This distribution will ideally be done with an angle of 60 degrees. In this variant, each extension thus has its center C′.

In a second embodiment visible in Figure 9, the spring 12 is a spring ring 120. Such a spring ring 301 comprises internal radial extensions 121 arranged between annular portions 122. These internal radial extensions 121 are constituted by the strip forming the ring 120 which is curved towards the inside of the ring, the whole forming a peripheral ring shape 12'. These internal radial extensions 121 are preferably regularly distributed around the circumference of the flat ring 120 so that the latter can act in a homogeneous manner. These internal radial extensions 121 each include the support head 14 according to the invention. It is then understood that the spring ring 120 can be oriented in any way with respect to the support block 1. This support block 1 also comprises a peripheral rim provided with a peripheral protruding portion extending towards the inside of the block support. The peripheral protruding portion may include a notch allowing the spring ring 120 to be put in place, said peripheral protruding portion serving to hold the spring ring in place.

[0036] Preferably, the spring ring may comprise three internal radial extensions. In this case, the peripheral protruding portion may comprise three notches allowing the installation of the spring ring via a bayonet insertion, said extension serving to retain the spring ring in place.

It will be understood that various modifications and / or improvements and / or combinations obvious to those skilled in the art can be made to the different embodiments of the invention described above without departing from the scope of the invention defined by the appended claims.

Claims (7)

1. Shock-absorbing bearing for a rod (3a) of an axis (3) of a mobile of a timepiece comprising a support block (1) intended to be driven, fixed or formed in the frame of said timepiece, said support block (1) being provided with a housing (6) designed to receive an axially deformable spring (12) and a bezel (20) supporting a drilled stone (4) through which the shank (3a) passes ) and a counter-pivot stone (5), the spring (12) being arranged in the housing (6) between the bezel and at least one projecting portion of a peripheral rim of the support block, characterized in that the spring ( 12) is formed by a peripheral ring (12 ') from which extend at least one extension (13, 121) provided with a support head (14) in contact with the counter-pivot stone, this head of support having the shape of an arc of a circle whose interface with the extension is via its convex face. 2. Shock-absorbing bearing according to claim 1, characterized in that said spring comprises two arms (12a) in the form of an arc of a circle connected to each other via a crosspiece (12b) and having two free ends each comprising a zone of support (12c), said at least one extension extending from one of the two arms (12a). 3. Shock-absorbing bearing according to claim 2, characterized in that said bearing head (14) has a greater curvature than that of the arms (12a) 4. Shock absorber bearing according to claim 1, characterized in that said spring is formed of a curved band in order to produce internal radial extensions (121) arranged between annular parts (122), said internal radial extensions (121) carrying the headrests. 5. Shock absorber bearing according to one of the preceding claims, characterized in that the spring comprises two diametrically opposed extensions. 6. Shock absorber bearing according to one of the preceding claims, characterized in that the spring comprises three extensions. 7. Shock absorber bearing according to claim 6, characterized in that the three extensions are evenly distributed.