Guide bearing of a timepiece balance pivot

Abstract

Bearing (1a) for guiding along an axis of a clockwork shaft, in particular a bearing for a portion of a shaft of a clockwork resonator, comprising at least one support element (13a) arranged to exert, radially to the axis or substantially radially to the axis, an action on the shaft, in a permanent manner.

Description

[0001] The invention relates to a rotational guide bearing for a timepiece arbor, in particular a guide bearing for a portion of the arbor or a pivot of a timepiece resonator, in particular a guide bearing for a timepiece balance wheel tigeron. The invention also relates to a watch shock absorber or anti-shock device comprising such a bearing. The invention also relates to a watch mechanism comprising such a bearing or such a shock absorber. The invention further relates to a watch movement comprising such a bearing or such a shock absorber or such a mechanism. The invention also relates to a timepiece comprising such a bearing or such a shock absorber or such a mechanism or such a movement.

[0002] Conventional balance wheel pivoting devices or guide bearings induce more or less significant friction on the balance wheel pivots depending on the position of the oscillator. In general, friction is higher in the vertical position of the watch, also called the "hanging" position, than in the horizontal position of the watch or "flat" position, which means that the oscillation amplitude of the balance wheel is lower in the vertical positions than in the horizontal positions of the watch. A difference in amplitude can notably result in a difference in rate, hence the importance for the accuracy of the timepiece of minimizing the "flat-hanging", that is to say the difference in rate between the "flat" position and the "hanging" position.

[0003] Within conventional balance wheel pivot devices, friction in different positions varies because the contact configurations between the balance pivots and the guide stones change. In a horizontal watch position, the balance shaft is vertical and the tip of the shaft pivot rests on a stone called a counter-pivot. Generally, this stone is flat and the tip of the pivot is rounded, which means that the radius of the friction surface is small and the resulting friction is low. In a vertical watch position, the balance shaft is in a horizontal position and rubs on the edge of a hole, generally an olive-shaped and / or rounded-edged hole in a stone. Friction is greater and the amplitude of oscillation of the balance is therefore lower than in a horizontal watch position.

[0004] Document CH239786 discloses a pivoting device combining an olive-plated stone and a counter-pivot stop inclined relative to the shaft. This makes it possible to permanently induce friction of the cylindrical part of the shaft against the olive-plated stone in the horizontal watch position, and therefore to increase the friction in this position.

[0005] Document US2654990 discloses a pivot with a flat end and slightly rounded edges rubbing against a counter-pivot provided with a hemispherical depression. The aim here is also to increase friction in the horizontal watch position by maximizing the friction radius of the contact surface of the pivot in such a position.

[0006] In the same vein, patent application CH704770 proposes a pivot ending in a bevel with a view to increasing friction in the horizontal watch position.

[0007] Due to the pivoting clearances, particularly radial clearances, the above-mentioned designs induce different contact configurations between the pivot and the jewel depending on the position of the watch. There therefore remain differences in operation between the horizontal and vertical positions.

[0008] Monobloc shock absorbers are also known in which the pivoting means of the balance pivot are manufactured in a single piece with return means. For example, document CH700496 relates to a simplified monobloc shock absorber whose guide means of the balance pivot bearing are implemented by elastic return means of the shock absorber body. In conventional operation of the timepiece, these elastic return means press the pivot bearing against a stop formed by the shock absorber body so that they have no effect on the balance pivot. Furthermore, no information is given on the chronometric performance of such a device.

[0009] Document CH701995 relates to a bearing which has the particularity of being pressed against a balance pivot under the effect of a spring arranged so as to apply a force directed axially relative to the shaft of the balance pivot. The bearing and the spring are preassembled within a pivot structure ready to be mounted on the watch movement. The aim is to eliminate movements of the pivot, and therefore variations in the contact configuration between the pivot and the bearing, due to changes in the position of the watch. Thus, during operation of the timepiece, the spring is prestressed so that it can act on the balance pivot, unlike a lyre of a conventional shock absorber which acts only by reaction in the event of an impact under the effect of the longitudinal movement of the balance pivot. In preferred embodiments, the spring has a geometry close to that of a lyre.Alternatively, the spring may be in the form of a helical spring. It is also mentioned that the bearing and the spring may be in one piece. Such a solution is not optimal since the preload of the spring is dependent on the axial location of the pivot structure, and therefore in particular on numerous assembly tolerances. Document CH701995 also discloses means for adjusting the preload of the spring by axial displacement of the pivot structure, for example by means of a bearing body whose outer periphery is threaded so that it can cooperate with a tapping formed on a balance bridge. Furthermore, it is also indicated that the force produced by the spring is dimensioned in such a way that it allows appropriate behavior of the pivot device in the event of an impact. The pivoting and damping functions are therefore dependent on each other.

[0010] Patent application CH709905 discloses various embodiments of blade pivots. In one embodiment, two blades supported by a balance are held in abutment in the bottom of grooves under the effect of elastically deformable arms. Such a structure requires a complex construction, defining two distinct virtual pivot shafts. In alternative embodiments, blades returned by elastically deformable arms can define the same virtual pivot axis, but must be arranged in distinct planes. Such embodiments are also not suitable for a conventional balance structure. In particular, the oscillation amplitude on such pivots is very limited.

[0011] The aim of the invention is to provide a guide bearing making it possible to overcome the drawbacks mentioned above and to improve the clock bearings known from the prior art. In particular, the invention proposes a guide bearing of simple structure and making it possible to minimize the difference existing between the torques resisting the oscillation of a resonator in the different clock positions.

[0012] A guide bearing according to the invention is defined by claim 1.

[0013] Different embodiments of the bearing are defined by claims 2 to 9.

[0014] A shock absorber according to the invention is defined by claim 10.

[0015] A mechanism according to the invention is defined by claim 11.

[0016] A preferred embodiment of this mechanism is defined by claim 12.

[0017] A movement according to the invention is defined by claim 13.

[0018] A timepiece according to the invention is defined by claim 14.

[0019] The attached figures represent, by way of examples, embodiments of a timepiece according to the invention.

[0020] There figure 1 is a schematic view of an embodiment of a timepiece comprising a first embodiment of a guide bearing.

[0021] There figure 2 is a perspective view of a first variant of the first embodiment of the guide bearing.

[0022] THE figures 3 et 4 are partial views of the first variant of the first embodiment of the guide bearing, a balance shaft being guided by the bearing.

[0023] There figure 5 is a schematic view of a second variant of the first embodiment of the guide bearing.

[0024] There figure 6 is a schematic view of a third variant of the first embodiment of the guide bearing.

[0025] There figure 7 is a perspective view of a second embodiment of the guide bearing.

[0026] THE figures 8 And 9 are schematic views of the second embodiment of the guide bearing, a balance shaft being guided by the bearing.

[0027] There figure 10 is a schematic view of the second embodiment of the guide bearing, without a balance shaft guided by the bearing.

[0028] THE figures 11 à 13 are schematic views illustrating overall bearing structures applicable in particular to the first embodiment of the guide bearing or to the second embodiment of the guide bearing.

[0029] There figure 14 is a front view of a first variant of a third embodiment of the guide bearing.

[0030] There figure 15 is a front view of a second variant of the third embodiment of the guide bearing.

[0031] There figure 16 is a front view of a third variant of the third embodiment of the guide bearing.

[0032] There figure 17 is a graph illustrating, for the different watch positions, the changes in the quality factor FQ of a resonator whose balance is guided by a bearing according to the prior art, as a function of the amplitude A of the oscillations of the resonator.

[0033] There figure 18 is a graph illustrating, for the different watch positions, the changes in the quality factor FQ of a resonator whose balance is guided by a bearing according to the second embodiment, as a function of the amplitude A of the oscillations of the resonator.

[0034] An embodiment of a timepiece 130 is described below with reference to the figure 1 . The timepiece is, for example, a watch, in particular a wristwatch. The timepiece includes a watch movement 120, in particular a mechanical watch movement.

[0035] The movement comprises a clockwork mechanism 110, in particular an oscillator connected to a power source, such as a barrel, by a finishing gear train. The oscillator comprises a resonator, in particular a resonator of the sprung balance type. The resonator comprises a shaft 2 (shown, for example, schematically in the figures 3 et 4 ), for example a balance shaft.

[0036] The mechanism comprises at least one guide bearing, in particular at least one bearing 1a; 1b; 1a'; 1b'; 1c' for guiding the resonator in rotation, at a portion of the shaft. This at least one bearing is advantageously part of a damper 100 forming part of the mechanism. Preferably, to guide the resonator in rotation, the mechanism comprises two dampers 100 each comprising a bearing for guiding the resonator. Preferably, the resonator is pivoted on either side of the shaft 2 by two bearings. Advantageously again, the mounting of the resonator shaft in the guide bearing causes the elastic deformation of at least part of the bearing. It follows that after mounting the shaft in the guide bearing, the latter is prestressed.

[0037] Advantageously, the dampers 100 comprise a counter-pivot stone returned to a stable position by the action of a spring and capable of being moved axially relative to the axis of the resonator against the action of the spring in the event of an impact or acceleration moving the resonator against this counter-pivot stone. The spring known as a lyre is provided to take up the forces of the resonator shaft via the counter-pivot stone, the function of which is to delimit the play, in particular the axial play, of the resonator shaft. In the event of an impact, the forces experienced by the shaft are taken up by the lyre via the counter-pivot stone. In conventional operation of the timepiece, the lyre presses the counter-pivot jewel and the pivot jewel against a stop predefined by the shock absorber body so that the lyre has no axial effect on the resonator shaft.Thus, the resonator shaft is mounted with axial play within the damper.

[0038] The dampers 100 may comprise a pivot stone. In this case, the resonator may, in the event of an impact or acceleration moving the resonator radially relative to the axis of the resonator against the action of the guide bearing, come to abut against this pivot stone, after the bearing has been deformed by a certain degree.

[0039] Alternatively, the shock absorber(s) 100 may not include a pivot stone. In this case, the guide bearing 1a; 1b; 1a'; 1b'; 1c' may replace the pivot stone of a shock absorber known from the prior art.

[0040] Generally, the guide bearing 1a; 1b; 1a'; 1b'; 1c' guides, along an axis 21, the shaft 2, in particular the shaft of the resonator. The bearing comprises at least one support element 13a; 13b; 131a; 132a; 13a'; 13b'; 13c' arranged so as to exert, radially to the axis or substantially radially to the axis, an action on the shaft, in particular a force on the shaft, permanently. The action may however be inclined relative to the direction radial to the axis 21 due to the coefficient of friction at the support element-shaft interface.

[0041] Preferably, the action or actions are exerted perpendicular to the axis 21 of the shaft. The rotational guidance function can therefore be dissociated from the axial force absorption function. For example, the direction of the action or actions forms an angle of less than 20° or less than 10° or less than 5° with a plane perpendicular to the axis 21.

[0042] By "exercise permanently" is meant to exert the action(s) constantly over time, when the resonator is in place in the rest of the movement, regardless of the position of the movement in space, in particular regardless of the position of the resonator in space. The contact between a support element and the shaft may nevertheless be broken momentarily when the movement is subjected to an acceleration greater than a predefined threshold, for example a threshold of the order of 1g which corresponds to the intensity of the Earth's gravitational field, in particular a threshold between 0.1g and 1g. Such a threshold interval advantageously makes it possible to optimally size the bearing with regard to energy considerations, in particular with regard to the friction induced by the bearing against the shaft. The acceleration threshold may nevertheless be set at any other value, in particular preferably at any other value greater than or equal to 1g, in particular of the order of 2g.

[0043] Advantageously, the intensity of the torque resisting the movement of the resonator due to the action or actions exerted by the at least one support element on the shaft is constant or substantially constant, in particular constant over time, when the resonator is put in place in the remainder of the movement and when the resonator is in movement, whatever the position of the movement in space, in particular whatever the position of the resonator in space. Advantageously, the intensity of the action or actions exerted by the at least one support element on the shaft is constant or substantially constant, in particular constant over time, once the resonator is put in place in the remainder of the movement, whatever the position of the movement in space, in particular whatever the position of the resonator in space.

[0044] The shaft portion guided by the bearing may be a pivot or a tang. The pivot may in particular have a cylindrical or truncated cone section.

[0045] The bearing comprises at least one return element 12a; 12b; 12a'; 12b'; 12c' cooperating with the at least one support element. Thus, it is the at least one return element 12a; 12b; 12a'; 12b'; 12c' which returns the at least one support element 13a; 13b; 131a; 132a; 13a'; 13b'; 13c' into contact with the shaft 2. This at least one return element is advantageously elastically deformable. Thus, the return force of the at least one support element on the shaft is produced by the elastic deformation of the at least one return element. The at least one return element is defined or sized so as to ensure the permanence of the contact as long as the acceleration undergone by the timepiece remains below the acceleration threshold described previously.

[0046] In a first embodiment described below with reference to the figures 2 à 6 , the bearing comprises at least one curved blade 14a, in particular three curved blades, or even more than three curved blades, in particular four or five curved blades, each constituting: at least one support element 13a on the shaft, and a return element 12a of the at least one support element on the shaft.

[0047] Preferably, the blades are curved in a spiral shape. The spiral may in particular be such as defined by a polar equation in which the radius is proportional to the angle or in which the radius is proportional to the angle raised to a power. Alternatively, the blades may have any shape as long as they have adequate stiffness. They may have a zigzag, straight, or curved shape. The blades may be curved by more than 180°, in particular approximately 270°, between their two ends. The curved shapes of the blades make it possible to optimize their size for a given dimensioning so as to obtain mechanical stress characteristics in the blades and stiffness characteristics of the blades that are adequate for the application. The shapes of the blades may be planar (in particular in a plane perpendicular to the axis of the bearing). The shapes of the blades may also be non-planar.This makes it possible to increase the active lengths of the blades.

[0048] In a first variant of the first embodiment described below with reference to the figures 2 à 4 , the bearing mainly comprises a frame 11a, in particular an annular frame, and blades 14a extending towards the inside of the frame, in particular three blades. The blades extend for example from an internal surface of the annular frame. Each blade has a convex face and a concave face. A first end of each blade is attached or fixed to the frame. A second end of each blade is free. In the vicinity of these second free ends, the concave faces can form the support elements on the shaft. Each support element is for example a portion of a concave face in the vicinity of a free end of a blade. In the variant shown, the support elements are formed at the face portions by concave surfaces. The radii of curvature of these concave surfaces are greater than the radius of the shaft 2 that the bearing is intended to receive.For example, the radii of curvature of these concave surfaces at the support elements are greater than 5 times the radius of the shaft 2 that the bearing is intended to receive.

[0049] Each support element is mechanically connected to the frame by means of a return element. This return element is made up of the blade part separating: the concave face portion constituting the support element of the chassis.

[0050] The diameter of the internal face of the chassis can be 30 times, or even 40 times, the diameter of the shaft 2.

[0051] In a second variant of the first embodiment described below with reference to the figure 5 , the bearing differs from the bearing described in the first variant of the first embodiment in that the support elements 131a extend perpendicularly or substantially perpendicularly to the free ends of the blades in a plane perpendicular to the axis 21. Thus, the support elements 131a are, in this variant, cylinder portions arranged perpendicularly or substantially perpendicularly to the free ends of the blades. Such a conformation in particular promotes the positioning and stability of the pivot relative to the bearing. Thus, it can be guaranteed that the axis 21 of the shaft 2 remains in a defined vicinity of its centered position in the bearing even under the effect of significant forces on the resonator.

[0052] In a third variant of the first embodiment described below with reference to the figure 6 , the bearing differs from the bearing described in the second variant of the first embodiment in that the support elements 132a comprise stops or hooks 133a arranged so as to limit the deformations of the return elements 12a. Thus, it can be guaranteed that the axis 21 of the shaft 2 remains in a defined vicinity of its centered position in the bearing even under the effect of significant forces on the resonator. This avoids any risk of breakage of the blades during assembly of the bearing, in particular when placing the shaft 2 in the bearing, or during operation of the movement when the resonator is in motion. The stops are for example formed by arms extending substantially perpendicular to the surfaces of the support elements which bear against the shaft. These stops are intended to cooperate with another adjacent support element of the bearing. On the figure 6 , the different elements are represented in a configuration where the stops are not active, that is to say a configuration where they do not cooperate by contact with an adjacent element.

[0053] In a second embodiment described below with reference to the figures 7 à 10 , the bearing differs from the bearing described in the first embodiment in that the blades 14b are straight or rectilinear (and not curved). Furthermore, in this embodiment, the surfaces of the support elements in contact with the shaft 2 are flat. The flexible blades are therefore in the form of straight beams. Their sections can be constant.

[0054] In this embodiment, the bearing comprises stops limiting the deformation of the return elements. Indeed, the blades remain close to surfaces 16 of the chassis constituting stops. When a certain degree of deformation of a return element is reached, the blade comes into contact against this stop and its deformation is thus limited. This avoids any risk of breakage of the blades during assembly of the bearing, in particular when placing the shaft 2 in the bearing, or during operation of the timepiece when the resonator is in motion, in particular in the event of an impact.

[0055] Regardless of the variant among the first two embodiments, the return elements are constituted by a part of a flexible blade. Preferably, the different flexible blades are made from a single piece, thus forming a single-piece bearing including the chassis.

[0056] Regardless of the variant among the first two embodiments, the resonator shaft can be pivoted between the flexible blades. Regardless of the position of the resonator, the blades, in particular the support elements, are pressed against the shaft under the effect of their respective prestress. Indeed, the blades, in particular the return elements, are elastically deformed when the shaft is introduced into the bearing. This elastic deformation causes a return force tending to return the blades to their original position when the shaft is introduced.

[0057] As shown in the figure 3 , in the horizontal position of the watch (vertical position of axis 21), each of the blades exerts the same force, ideally minimized as much as possible, on the shaft. This force is ideally suitable for inducing friction substantially equal to the friction acting in the vertical position. The contact between the blades and the shaft can be broken momentarily when the movement is subjected to an acceleration greater than a predefined threshold. A threshold which can be between 0.5g and 1g advantageously makes it possible to minimize as much as possible the friction of the blades against the shaft.

[0058] In the horizontal position of the watch, the weight of the arbor is theoretically not taken up by the bearing. The weight is, for example, taken up by a counter-pivot stone. As shown in the figure 4 , in the vertical position of the watch (horizontal position of axis 21), the weight of the resonator is taken up by the blade(s) of the bearing. This causes a slight displacement (perpendicular to axis 21). This displacement is advantageously similar to or smaller than those known within conventional bearings. As a result of this displacement, the blade(s) located above the shaft exert a weaker force on the shaft than those located below. As long as all the blades remain in contact with the shaft, the sum of the intensities of the forces of the blades on the shaft remains essentially the same regardless of the position of the resonator. When the resonator is mobile in the movement, the intensity of the friction torque resulting from the forces of the blades on the shaft then also remains essentially the same regardless of the position of the resonator. This has the effect of balancing the quality factors of the resonator between the different watchmaking positions.

[0059] On the figure 10 , a bearing is partially represented, in the absence of the shaft mounted in the bearing. In this configuration, the three blades define an inscribed circle of radius r0.

[0060] When mounting the shaft in the bearing, the flexible blades are elastically deformed, or prestressed, over a distance rp-r0, rp being the radius of the shaft at the level of the support of the blades on the shaft.

[0061] The prestressing force F0 of each of the flexible blades is thus given by: F0 =k.(rp-r0) where k is the stiffness of each of the flexible blades.

[0062] Studies, based on static force balances, show that the static friction torque C induced by the flexible blades against the resonator shaft is constant or substantially constant regardless of the position of the resonator in space, and that this essentially depends on: this prestressing force F0 (as long as it is strictly positive at the level of each of the blades), the coefficient of friction η between the shaft and each of the flexible blades, and the radius rp of the shaft.

[0063] Thus, the static friction torque C, whatever the position of the resonator, is equal or substantially equal to the static friction torque CH induced by the flexible blades against the resonator shaft when the watch is in a horizontal position (shaft 2 and axis 21 oriented vertically). In this configuration shown in the figure 9 , and assuming that the weight P is oriented exclusively along the axis of rotation of the shaft) of the resonator, the torque CH can be expressed as follows: CH = 3 . η . F 0 . rp ou CH = 3 . η . k rp − r 0 . rp So : C = 3 . η . F 0 . rp ou C = 3 . η . k rp − r 0 . rp

[0064] This value C being constant or substantially constant whatever the position of the watch, it therefore has the effect of balancing the quality factors of the oscillator between the different positions.

[0065] For example, the figure 18 illustrates a graph representing different quality factors FQ according to the amplitude of the oscillations of an oscillator and the spatial position of a watch equipped with an oscillator pivoted by two bearings such as that illustrated in the figure 7 . We observe that these quality factors FQ are homogenized whatever the position of the resonator, and this in a significant manner compared to the quality factors FQ of the same resonator rotated in a conventional manner represented on the figure 17 .

[0066] The prestressing force F0 can be minimized as much as possible depending on the resonator chosen so as to optimize the energy required to maintain its oscillations. The minimum intensity of the force Fm is defined by the limiting case in which the force Fi (F2 on the figure 8 ) produced by one of the flexible blades is cancelled out under the effect of the weight of the resonator (1g maximum acceleration). Calculations show that this case cannot be reached if, at constant friction η: F0>2.P / 3 with P the force exerted by the resonator at the bearing

[0067] By respecting this criterion, F0 can be minimized as best as possible so as to produce the lowest possible static friction torque while balancing the friction torques in all horizontal and vertical positions.

[0068] More specifically, the stiffness k of each of the flexible blades must meet the criterion: k > 2 . P / 3 . rp − r 0

[0069] Regardless of the variant among the first two embodiments, the sections of these blades may or may not be constant. Each of these blades may also be made up of several blades, integral or not, so as to optimize and differentiate their stiffness according to the different displacements or positions of the resonator. For example, such an embodiment would minimize the radial support force against the shaft in order to minimize the friction forces against the shaft while ensuring the centering of the axis in the bearing.

[0070] Whichever variant is among the first two embodiments: the blade(s) extend parallel or substantially parallel to the support elements in the vicinity of the support elements and / or orthogonally or substantially orthogonally to the axis in the vicinity of the support elements, or the blade(s) extend perpendicular or substantially perpendicular to the support elements in the vicinity of the support elements and / or orthogonally or substantially orthogonally to the axis in the vicinity of the support elements.

[0071] Regardless of the first and second embodiments, the blades, and more generally the bearings, may for example be made of nickel, a nickel-phosphorus alloy, or even silicon and / or coated silicon (silicon oxide, silicon nitride, etc.). Such components may preferably be manufactured by electroforming or etching. Alternatively, such components could be machined by electroerosion.

[0072] In a third embodiment described below with reference to the figures 14 à 16 , the bearing comprises at least one radial or substantially radial protuberance 14a', 14b', each protuberance comprising: at least one support element on the shaft, and a return element of at least one support element on the shaft.

[0073] Thus, preferably, the bearing comprises a ring having a geometry including several protrusions or lobes directed towards the axis of the ring, in particular directed towards the axis of the ring and extending from a surface of the ring directed towards the inside of the ring. Preferably, the ring comprises at least two protrusions. It may in particular comprise two or three or four or five or six protrusions.

[0074] Preferably, the bearing comprises a ring made of elastomeric material. The bearing may be made of natural rubber or synthetic rubber such as neoprene, polybutadiene, polyurethane or silicone.

[0075] Alternatively, the ring may have a constant section. In this case, it may have a support element comprising a continuous surface bearing on the shaft over its entire circumference or over the majority of its circumference, for example more than 240° or more than 270° or more than 300°. In this variant, the bearing therefore comprises a single support element on the shaft. This support element is constituted by the surface in contact with the shaft. An annular part of the ring located between the surface in contact with the shaft and the surface of the largest diameter of the ring constitutes a return element, in this case a single return element.

[0076] In a first variant of the third embodiment described below with reference to the figure 14 , the bearing 1a' comprises three protrusions 14a'. Each protrusion comprises a support element 13a' on the shaft and a return element 12a' of the support element in contact with the shaft. The support elements are constituted by surfaces of the protrusions in contact with the shaft. The return elements are constituted by the material of the protrusions connecting the support elements to the rest of the ring 11a' constituting a frame and having a constant section. The protrusions are lobes or bosses filled with material.

[0077] In a second variant of the third embodiment described below with reference to the figure 15 , the bearing differs from the first variant of the third embodiment of the bearing in that the protrusions are lobes or bosses in which cutouts 91 have been made. Thus, the bearing may comprise at least one radial or substantially radial protrusion, each protrusion comprising at least one support element on the shaft and a return element of at least one support element on the shaft, the return element(s) comprising cutouts. By "cutout" is meant here any recess which may in particular have been made by a technique other than a cutout, in particular by molding. These cutouts 91 make it possible to adjust the stiffness of each of the protrusions.

[0078] In a third variant of the third embodiment described below with reference to the figure 16 , the bearing differs from the first variant of the third mode or the second variant of the third mode in that the ring is mechanically linked to, in particular fixed to, in particular overmolded on, a ring 11c' constituting the chassis.

[0079] Whatever the embodiment and whatever the variant, the at least one return element and the at least one support element are preferably in one piece.

[0080] In the variants and embodiments described, the bearing has three return elements and three support elements. However, whatever the embodiment and whatever the variant, the bearing may have a different number of three return elements and three support elements. In particular, whatever the embodiment and whatever the variant, the bearing may have one or two or three or four or five or six return elements and one or two or three or four or five or six support elements. Preferably, the bearing has as many return elements as support elements.

[0081] Regardless of the embodiment and regardless of the variant, the bearing surface bearing against the shaft 2 of each bearing element may be flat, concave, or convex. In particular, all the bearing surfaces may be flat, concave, or convex.

[0082] Whatever the embodiment and whatever the variant, the frame, in particular the annular frame, can be manufactured in one piece or made of several independent parts, in particular as many independent parts as there are return elements. In the case where the blades are produced independently of each other, they are each fixed to a base 111a. The bases are advantageously provided with positioning elements and possibly adjustment elements, in particular centering elements, such as holes. These positioning elements make it possible to define the axis of the bearing. Such a base construction is shown in figure 12 The positioning elements cooperate, for example, with pins.

[0083] Regardless of the embodiment and regardless of the variant, the bearing may be provided with means for assembling the bearing. For example, the frame may include a split ring so as to allow its elastic deformation and thus allow adequate positioning of the blades during assembly as shown in the figure 13 . The chassis may also include a continuous ring as shown in the figure 11 .

[0084] Whatever the embodiment and whatever the variant, the bearing may include stops to limit the deformation of the return elements.

[0085] Whatever the embodiment and whatever the variant, the support elements and / or the return elements are preferably regularly distributed angularly around the axis 21.

[0086] The solutions described aim to remedy the problem of difference in speed between positions by proposing a bearing shaped so as to generate an essentially constant force on a shaft of a resonator, regardless of the position of the resonator. To do this, the bearing has the particularity of being equipped with at least one return means provided to apply a substantially radial force against a shaft of the resonator, regardless of the position of the resonator.

[0087] The bearing is provided with at least one return means which is designed to apply a substantially radial force against the shaft so as to induce an essentially constant force between the shaft and the bearing, regardless of the position of the watch.

[0088] In this way, the rate difference between positions is reduced to the strict minimum. Thus, the quality factor of the resonator can be constant or substantially constant regardless of the position of the resonator, and the chronometric performance of the movement optimized.

[0089] The return means primarily has the function of supporting and positioning, at least in the transverse plane of the bearing, the resonator shaft.

[0090] Whatever the embodiment, the bearing can be integrated within a shock absorber, in particular within a shock absorber with a conventional structure.

[0091] In a shock absorber according to the invention, it is noted that an axial damping function can be dissociated from the radial damping function. Indeed, the axial damping is mainly ensured by a conventional counter-pivot stone and lyre. A radial damping function can be ensured by the bearings.

Claims

1. Bearing (1a; 1b; 1a'; 1b'; 1c') for guiding a portion (2) of a timepiece resonator shaft about an axis (21), the bearing comprising at least one pressing element (13a; 13b; 131a; 132a; 13a'; 13b'; 13c') arranged in such a way as to constantly exert an action on the shaft, radially or substantially radially with respect to the axis, the bearing being characterized in that: (a) it comprises at least one blade (14a; 14b), notably three blades, or even more than three blades, each one constituting: - at least one said pressing element (13a; 13b; 131a; 132a) for pressing on the shaft, and - a return element (12a; 12b) for returning the at least one said pressing element to press on the shaft, or (b) it comprises at least one radial or substantially radial protuberance (14a'; 14b'), each protuberance comprising: - at least one said pressing element (13a'; 13b'; 13c') for pressing on the shaft, and - a return element (12a'; 12b'; 12c') for returning at least one said pressing element to press on the shaft.

2. Bearing according to Claim 1 and proposition (a), characterized in that: - the blade or blades extend parallel or substantially parallel to the pressing elements in the vicinity of the pressing elements and / or orthogonally or substantially orthogonally with respect to the axis in the vicinity of the pressing elements, or in that - the blade or blades extend at least substantially perpendicular to the pressing elements in the vicinity of the pressing elements and / or orthogonally or substantially orthogonally with respect to the axis in the vicinity of the pressing elements.

3. Bearing according to Claim 1 and proposition (a) or according to Claim 2, characterized in that the blade or blades extend at least substantially in a straight line, or in that the blade or blades extend in curves, notably at least substantially in spirals.

4. Bearing according to one of the preceding claims, characterized in that the at least one return element (12a; 12b; 12a'; 12b'; 12c') collaborates with the at least one pressing element.

5. Bearing according to the preceding claim, characterized in that the at least one return element (12a; 12b; 12a'; 12b'; 12c') and the at least one pressing element are made as one piece.

6. Bearing according to one of the preceding claims, characterized in that it comprises at least two pressing elements (13a; 13b; 131a; 132a; 13a'; 13b'; 13c') for pressing on the shaft about the axis (21).

7. Bearing according to one of the preceding claims, characterized in that it comprises at least two return elements, notably three return elements, and at least as many pressing elements.

8. Bearing according to one of the preceding claims, characterized in that each of the at least one pressing element comprises at least one planar or concave or convex pressing surface (9), notably all the pressing surfaces being planar or concave or convex.

9. Bearing according to one of the preceding claims, characterized in that it comprises an annular chassis (11a; 111a; 112a; 11b; 112b; 11a'; 11b'; 11c'), the pressing elements being mechanically connected to the chassis via the return elements, and / or in that the annular chassis is manufactured as a single piece or produced in several independent components, notably in as many independent components as there are return elements, and / or in that it comprises end stops (133a) limiting the deformation of the return elements, and / or in that the pressing elements and / or the return elements are uniformly angularly distributed about the axis (21).

10. Shock-absorber (100) comprising a bearing (1) according to one of the preceding claims and an endstone jewel.

11. Horology mechanism (110), notably a balance oscillator, comprising at least one bearing according to one of Claims 1 to 9 or a shock-absorber according to the preceding claim and a shaft (2) mounted in the at least one bearing.

12. Mechanism according to the preceding claim, characterized in that the mechanism comprises a resonator comprising a balance, and / or in that the mechanism comprises a resonator of which a shaft portion or pivot shank is guided by the bearing, and / or in that the at least one return element is preloaded.

13. Horology movement (120) comprising at least one bearing according to one of Claims 1 to 9 or a shock-absorber according to Claim 10 or a mechanism according to Claim 11 or 12.

14. Timepiece (130), notably a wristwatch, comprising a movement according to the preceding claim or a mechanism according to Claim 11 or 12 or a shock-absorber (100) according to Claim 10 or at least one bearing according to one of Claims 1 to 9.

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