CH712163A1 - Ball bearing and coupling system comprising such a ball bearing. - Google Patents

Abstract

The invention relates to a ball bearing (1) comprising an outer ring (11), an inner ring (12), balls (10a, 10b), and at least one segment (2) for separating said balls from each other. others, the segment being placed, in the radial direction, between said inner ring with which it is in contact and the outer ring. The segment comprises a braking element (240) and at least some of the balls can move relative to the segment so as to occupy a different relative position depending on the direction of rotation of said rings, so that in only one of the directions rotation, one of the rings can rotate independently of the other ring but being braked by the braking element. The invention also relates to a unidirectional coupling system, an oscillating weight suspension and an automatic watch comprising such a ball bearing.

Description

TECHNICAL FIELD [0001] The present invention relates to a ball bearing and a coupling system comprising a ball bearing. The present invention relates in particular to a clock-bearing ball bearing for a winding system in an automatic watch movement.

State of the art [0002] Document EP 1 134 626 describes a device for coupling an oscillating weight to a reduction gear in an automatic watch designed to simplify and compact the winding system of the mainspring. The coupling device used comprises two unidirectional coupling elements with superposed ball bearings. Each element makes it possible to transmit the bidirectional rotation movement of an oscillating mass unidirectionally to the mainspring. The two elements are arranged to transmit the rotation of the oscillating mass each in an opposite direction so that the movement of the winding mass is always transmitted to the mainspring regardless of its direction of rotation. However, the disadvantage of this construction lies in the large thickness of the coupling device due to the superposition of two ball bearing devices.

To save space, one could use a simple unidirectional clutch comprising a ball bearing. In this case, the oscillating mass drives the barrel spring only in one direction of rotation and is free to rotate in the other direction. This construction would have the advantage of being less thick but it has a major disadvantage: the free rotation movement of the oscillating mass generates a noise such that it becomes annoying for the user of the watch.

Several devices for damping the movement of the oscillating mass have been described in documents of the prior art.

CH 701 343 discloses a device for damping radial movements during an impact of an annular oscillating weight. Damping members support rollers in contact with the oscillating ring, these rollers are rotatably placed in a ball bearing. The damping members are in contact with elastic means connected to the plate and allow a radial play of the mass during an impact. This damping device acts neither on the amplitude nor on the rotational power of the annular oscillating mass.

[0006] EP 2 110 719 discloses a damping device for the oscillating weight of a self-winding watch comprising a plate whose one end is fixed to the ground and of which another end is fixed to a tube arranged to turn around. a shaft constituting the axis of rotation of said mass. The plate has at least one flexible zone capable of flexing in the event of shocks to the oscillating mass. A ball bearing is disposed between the shaft and the tube. This damping device does not limit the speed of rotation of the oscillating mass.

These documents illustrate damping devices protecting the movement in case of shock but do not limit the speed of rotation of the oscillating mass.

[0008] CH 332 550 describes a self-winding watch in which an oscillating mass has on its underside two clearances in which is disposed a U-shaped leaf spring whose free ends abut in turn against a pillar of so that the branches of the spring deform elastically to the extent permitted by the width of the clearances, thereby limiting the amplitude of the oscillations of the mass. This device has the disadvantage of limiting the stroke of the oscillating mass in both directions of rotation and thus the efficiency of reassembly.

[0009] US 3,901,021 discloses a ball-bearing clutch device in which a clutch spring is provided with sloping resilient pawls. The latter are oriented so as to engage in openings of a reduction gear whose teeth can engage with a pawl so as to rotate in the winding direction of the barrel In the opposite direction, of non-winding of the barrel , the elastic pawls slide with a slight resistance due to friction. This device has a disadvantage associated with the size of the pawls facing upwards in the thickness of a watch movement.

EP 0 924 579 discloses a device for limiting the mechanical power of an oscillating mass mounted elastically on a holding mobile to be braked by touching a bearing path and thus limit the power supplied when the latter substantially exceeds the powers supplied in normal use.

BRIEF SUMMARY OF THE INVENTION [0011] An object of the present invention is to provide a ball bearing for a mechanical watch free from the limitations of known devices.

Another object of the invention is to provide a ball bearing for oscillating weight that can be used to reduce noise in the direction of free rotation of the oscillating mass.

According to the invention, these objects are achieved in particular by means of a ball bearing comprising an outer ring, an inner ring, balls and at least one segment intended to separate said balls from each other, the segment being placed in the radial direction between said inner ring with which it is in contact and the outer ring, the segment comprising a braking element, at least some of the balls being movable with respect to the segment so as to occupy a different relative position according to the direction of rotation of said rings, so that, in the first direction of rotation only, one of the rings can rotate independently of the other ring but being braked by the braking element.

Such a bearing can be used to brake the oscillating mass when one of the rings drives the segments in the first direction of rotation. It is thus possible to design an automatic winding cylinder system in which the oscillating mass can rotate in one of the two directions of rotation without reloading the barrel, but still being braked by the ball bearing. This avoids the disadvantages of an oscillating mass rotating completely freely in a direction of rotation, often causing a disturbing noise.

The braking system can also be used to brake the wheel between the bearing and the barrel. This avoids unwanted rotation of the elements of this wheel when the gear is not driven by the oscillating weight.

The braking system is integrated in the ball bearing so that the assembly has a small footprint n.

The bearing is thus designed to exert a different braking according to the direction of rotation. Braking has the effect of preventing one of the rings and the segments from rotating freely relative to the other ring.

For this purpose, the braking system exerts a friction on one of the rings, for example on the inner ring.

The braking element of the ball bearing according to the invention may comprise a flexible blade in contact with one of the rings of the bearing, for example with the inner ring.

The bearing force of this flexible blade against the ring may be constrained by a ball bearing, said brake ball.

The ball bearing may comprise several segments, for example an odd number of segments, each having a flexible blade acting as a braking system.

Each segment may comprise an outer face facing the outer ring and an inner face in contact with the inner ring.

The different segments are placed between the inner and outer rings of the ball bearing, and thus serve as a cage for separating the balls from the bearing.

Each segment may extend between a first end and a second end on a segment angular sector, for example on an angular segment less than 120 °.

Each braking element may extend from the second end on a first angular sector smaller than the segment angular sector.

The configuration of the braking element ensures the necessary friction to slow down the braked ring without exerting excessive friction that would lead to premature wear of the inner or outer ring.

Each segment may have at least one notch in which a ball may move between a first position when the outer ring rotates in a first direction of rotation and a second position when the outer ring rotates in the second direction of rotation.

One or more brake beads may be mounted in one or more brake notches on the outer face of each segment. The brake balls may bear against the outer ring.

In another embodiment, the brake notch may be located against the inner ring, the brake ball can thus roll against the inner ring. According to one aspect, the invention also relates to a coupling system comprising a unidirectional ball bearing reducing noise in the direction of free rotation of the oscillating mass.

In a first embodiment, the bearing is arranged in such a way that the rotation of one of the rings in the second direction of rotation is transmitted without slipping, or virtually without sliding, to the segments and to the other ring. .

The second direction of rotation is opposite to the first direction.

Thus, in this first embodiment, the rotation of one of the rings in the first direction of rotation is not transmitted to the other ring; the ball bearing merely curbs a ring, or both rings. The rotation of one of the rings in the second is however transmitted to the segments and to the other ring.

In this first embodiment, the ball bearing is therefore unidirectional type ("one-way"), the braking element, however, creating a friction that prevents the free and unbraked rotation of the driving ring and / or or the ring driven in the first direction of rotation.

Such a bearing can for example be used in watchmaking in the work train between the oscillating weight and the barrel of an automatic winding system; it then makes it possible to transmit to the barrel the rotations of the oscillating mass in the second direction of rotation, and to allow this oscillating mass to rotate in the first direction of rotation without acting on the barrel, but nevertheless being braked.

In this first embodiment, each segment has a second notch, said notch blocking. The locking notch may be arranged in such a way that in the second direction of rotation at least one ball, called the locking ball, occupies a second position in the locking segment and is wedged between the outer ring of the bearing and the segment, making the outer ring and the inner ring rotational. In this embodiment, the locking ball can move between two positions of the locking notch.

When the locking ball is wedged between the outer ring and the segment, it can neither roll on itself nor move in the notch. The segment is then wedged between the two inner rings, thus allowing the inner ring to drive the outer ring in rotation at the same speed or vice versa, allowing the outer ring to drive the inner ring in rotation at the same speed.

When the locking ball arrives in this locking position, it causes a pivoting of the segment on itself, which effect reinforces the support between the braking element and the inner ring, and therefore reduce still the possible slip between the inner ring and the segment.

The locking notch of the ball bearing according to the invention may be arranged so that in the first direction of rotation (direction of braking), the locking ball occupies a first position in which it is free of to roll on itself. In this position, the braking element is pressed against the inner ring, so as to slow down its speed of rotation. The inner ring rotating in the first direction of rotation is then braked by the segment. The braking element, for example a blade connected to the segment, causes friction on the inner ring tending to slow its rotation.

The locking notch of the ball bearing according to the invention may have a first inclined portion extending from the first end towards the second end to a second portion forming a stop and substantially radial in the plane of the rolling. The first portion is at an angle less than 90 ° with the second portion.

According to the invention, the segment may have at least one first notch, called the brake notch, near the second end, in which a brake ball can move between a first position and a second position while being in contact with the outer ring.

According to the invention, the brake notch may have a first substantially radial portion, close to the locking notch and a second substantially radial portion near the second end of the segment. A brake ball can move between these two portions. When a locking ball rolls against the second portion of the locking notch, the brake ball rolls against the second portion of the brake notch and maintains pressure against the brake member which remains pressed against the inner ring , so as to slow the speed of rotation of the inner ring.

In this embodiment, the brake ball is placed in the brake notch so as to ensure braking of the inner ring, regardless of the direction of rotation. According to a variant of this first embodiment of the invention, the brake notch may have a first inclined portion, so as to change the braking intensity according to the position of the brake ball in the notch. The inclined portion may extend towards the second end of the segment, so as to increase the pressure of the brake bile when the brake ball is in the first position, in the braking direction.

The invention also relates to a unidirectional coupling system comprising a ball bearing according to the first embodiment of the invention, an integral input in rotation of the inner ring, an output integral in rotation with the outer ring, so that in a first direction of rotation, the rotational movement of the input is not transmitted to the output and the rotational speed of the inner ring and the outer ring is reduced by the braking member while in a second direction of rotation, the rotational movement of the input is transmitted to the output.

Such a coupling system can be used to couple an oscillating mass to a reduction gear so as to slow the rotation of the oscillating weight and / or the gear in a direction of rotation, whereas in the In other sense, the inner ring connected to the oscillating mass and the toothing of the outer ring of the bearing meshing with a reduction gear rotate at the same speed of rotation.

An automatic watch according to the invention may comprise the unidirectional coupling system described above, the input being kinematically connected to an oscillating mass and the output being kinematically connected to a mainspring, the kinematic connection with the output being able to understand a gear train.

The coupling system of such a watch makes it possible to brake the oscillating mass, in a direction of rotation, when it does not participate in winding the barrel. This braking avoids generating noise that becomes awkward for the wearer of the watch when the oscillating mass rotates too fast. In the opposite direction of rotation, the coupling system makes it possible to transmit the energy supplied by the rotation of the oscillating mass to the barrel.

According to a second embodiment of the invention, the ball bearing is arranged so that, in a first direction of rotation, the braking element is pressed against the inner ring to create a friction with the segment, while in the second direction of rotation, the stress on the brake element is released so that the segment is free to rotate relative to the inner ring.

For this purpose, each segment in this second embodiment comprises a first notch, said brake notch, in which a brake ball moves in the direction of rotation, so as to modify the braking intensity according to the direction of rotation (without blocking the relative displacement of the segment against the inner ring).

In the first direction of rotation, the brake ball occupies a first position bearing against the outer ring, which causes a rotation of the segment on itself, and the support of the braking element against the ring interior.

In the second direction of rotation, the brake ball occupies a second position without contact with the outer ring, or with a lower support. The release of this support causes a relaxation of the braking against the inner ring.

In this second embodiment, the brake notch may have an inclined portion against which the ball moves according to the direction of rotation, so as to modify the bearing against the outer ring.

The segment according to this second embodiment may have at least a second notch, said guide notch, for housing a guide ball for guiding the segment between the inner and outer rings, and to allow the outer ring of turn relative to the segment.

The guide segment can move in the guide slot without changing its support against the outer ring.

An oscillating mass suspension may comprise a ball bearing according to this second embodiment of the invention. Such a bearing allows the oscillating mass to rotate completely freely in a second direction of rotation while in the first direction of rotation, the oscillating mass is braked.

An automatic watch may comprise an oscillating weight carried by the suspension according to this second embodiment of the invention. Such a watch makes it possible to reduce the speed of rotation of the oscillating mass when it does not take part in the winding of the barrel, in the corresponding direction of rotation, thus reducing the noise generated by the oscillating mass. In the other direction of rotation, the speed of rotation of the oscillating mass is not slowed down, it can thus provide a maximum energy for the winding of the barrel.

BRIEF DESCRIPTION OF THE FIGURES [0056] Examples of implementation of the invention are indicated in the description illustrated by the appended figures in which:

Fig. 1 illustrates a sectional view of a ball bearing according to a first embodiment, the balls being in the locking position (2nd position).

Fig. 2 illustrates a sectional view of a ball bearing according to the first embodiment, the balls being in the braking position (first position).

Fig. 3 illustrates a perspective view of a ball bearing segment according to the first embodiment.

Fig. 4 illustrates a sectional view of a ball bearing according to a variant of the first embodiment, the wheels being in the braking position.

Fig. 5 illustrates a perspective view of a ball bearing segment according to a variant of the first embodiment.

Fig. 6 illustrates a perspective view of an oscillating mass meshing a coupling device according to the invention.

Fig. 7 illustrates a sectional view of the coupling device according to the invention.

Fig. 8 illustrates a sectional view of a ball bearing according to a second embodiment, the balls being in the guiding position (second position).

Fig. 9 illustrates a sectional view of a ball bearing according to a second embodiment, the balls being in the braking position (first position).

Fig. 10 illustrates a perspective view of a ball bearing segment according to the second embodiment.

Fig. 11 a sectional view of a suspension of oscillating mass according to the invention.

Fig. 12 illustrates a perspective view of an oscillating weight carried by the suspension according to the invention.

Example (s) of Embodiment of the Invention [0057] FIGS. 1 to 3 illustrate a first embodiment of the invention. This bearing is intended to transmit the rotations of an oscillating mass to the barrel when the oscillating mass rotates in a second direction of rotation, and to brake the oscillating mass without transmitting its movements when it rotates in the opposite direction. It can be mounted in the gear train between the oscillating weight and the cylinder of an automatic watch.

For this purpose, the ball bearing 1 shown in FIGS. 1 and 2 comprises three identical segments 2 placed between an outer ring 11 and an inner ring 12 of the bearing.

The number of segments 2 shown is not limiting, one could imagine a bearing 1 comprising a lower or greater number of segments 2. An odd number of segments is however desirable to balance the loads.

FIG. 1 shows a sectional view of a bearing according to this first embodiment. In this view, the segments 2 and the balls 10a, 10b occupy a second position, called the locking position, which is reached when the bearing is driven by the inner ring 12 rotating in a second direction of rotation, in this case the clockwise direction . In this position, the inner ring 12 rotates the segments 2 and the outer ring 11.

Each segment 2 comprises a first notch 201b, said brake notch, and a second notch 200a, or locking notch. A locking ball 10a is housed in each locking notch 200a and a brake ball 10b is housed in each brake notch 201b.

As can be seen in particular in FIG. 3, each locking notch 200a has a first inclined portion 2000 near the first end 21 of the segment 2 and a second portion 2001 forming a substantially radial abutment. In the second direction of rotation illustrated in FIG. 1, the locking balls 10a rise along the inclined portion 2000 and become wedged between the outer ring 11 of the bearing 1 and the segment 2. In this position, the segment 2 and the outer ring 11 rotate integrally.

Each segment 2 further comprises a braking element 240. This element is supported by the brake ball 10b against the inner ring 12, making rotationally integral the segments 2 and the inner ring 12. Thus the rotation in the direction time of the inner ring 12 causes rotation in the same direction and at the same speed of each segment 2 and therefore the outer ring 11. The outer ring 11 and the inner ring 12 are thus integral in rotation.

In this second direction of rotation, the brake beads 10b roll against the first portion 2010 of the brake notch. They push the second end 22 of the corresponding segment 2 against the inner ring, so as to press the brake element 240 against the inner ring. The slot 243 between the brake member 240 and the segment body 2 provides some resilience to the brake member 240 to compensate for machining tolerances.

FIG. 2 represents the position of the segments 2 and the balls 10a, 10b when the inner ring 12 rotates in the first direction of rotation, in this case the counterclockwise direction. Each locking ball 10a of the locking notch 200a occupies a first position, against the portion 2001. In the same way, each brake ball 10b occupying a first position, against the portion 2011 of the second notch 201. In this configuration the two balls 10a, 10b are free to roll on themselves. The braking element 240 is pressed against the inner ring 12 by the pressure exerted by the brake ball 10b, so that the rotation of the inner ring 12 in the clockwise direction is braked.

Figs. 4 and 5 illustrate a variant of the first embodiment differing in the configuration of the brake notch 201a. In this variant, the brake notch 201a is arranged to vary the pressure exerted by the brake ball 10b against the segment 2; the pressure is greater in the second direction of rotation (locking direction) than in the first direction of rotation (direction of braking), so as to increase the braking torque and further reduce the risk of sliding in the blocking direction .

For this purpose, the brake notch 201a has a first inclined portion 2010 along which the brake ball rises in the blocking direction.

FIG. 6 illustrates a unidirectional coupling system 6 comprising a ball bearing 1 according to the first embodiment, driven by an oscillating mass 4 whose axis is connected to the outer ring 11 of the bearing. The outer ring 11 of the unidirectional coupling system is intended to mesh a reduction gear (not shown) of a gear train or kinematic chain (not shown) connecting the oscillating mass 4 to the barrel (not shown).

FIG. 7 is a sectional view of the unidirectional coupling device 6 according to a first embodiment of the invention. The balls 10a, respectively 10b, placed in the notches 200a, respectively 201a or 201b of the segments 2, are held between on the one hand the outer ring 11 and on the other hand the inner ring 12 and the cone 13. The balls 10a, 10b thus have four points of contact with the rings and the cone 13 of the bearing. The cone makes it possible to close the bearing after the placement of the balls.

A second embodiment of the invention is shown in FIGS. 8 to 12. This embodiment may for example be implemented with an inner ring 12 fixed relative to the watch movement plate, and an oscillating weight 4 connected to the outer ring 11. The bearing 1 allows the oscillating weight 4 to turn freely in one direction (second direction), to raise the barrel, and to be braked in the first direction.

The ball bearing 1 shown in Figs. 8 and 9 comprises several identical segments 2, for example three segments 2, placed between the outer ring 11 and the inner ring 12 of the bearing 1.

FIG. 8 shows the position of the segments 2 and the balls 10b, 10c when the outer ring 11 rotates in a second direction of rotation, in this case the counterclockwise direction, and the inner ring 12 is fixed. Each segment 2 is provided with a brake notch 200b and a guide notch 201c. A brake ball 10b occupies a second position at the bottom of the brake notch 200b; it bears against a first notch portion 2000 substantially radial, and can turn on itself. A guide ball 10c occupies a first position in the guiding notch 201c, bearing against a first portion (2010) substantially radial, in which it can rotate on itself. In this case, the two balls 10b and 10c roll on themselves and the segment 2 is configured so that the braking element 240 does not rub against the inner ring 12 of the bearing 1. Therefore, the outer ring 11 and the segments 2 can freely rotate in the second direction (counterclockwise), without being braked.

FIG. 9 shows the position of the segments 2 and the balls 10b, 10c when the inner ring 12 is fixed while the outer ring 11 rotates in a first direction of rotation, in this case the clockwise direction. Each brake ball 10b in the first notch 200b rises along the second inclined portion 2001 towards a position bearing against the radial portion 2002. The brake ball 10b is then bearing against the outer ring 11 and pushes the segment 2 into position. pivoting it about itself in the direction of the inner ring 12. The brake member 240 then bears more against the inner ring 12, creating friction. The braking torque is adjusted automatically due to the deformation of the braking element 240 that allows the slot 243, reducing the gap 242 between the free end of the blade 240 and the end 22 of the segment. The rotation of the segments 2 and the outer ring 11 are thus braked. In this direction of rotation, the guide ball 10c is free to roll on itself in the guide notch 201c.

FIG. 10 illustrates a segment 2 according to the second embodiment of the invention.

FIG. 11 illustrates in section a suspension of oscillating mass 5 containing a ball bearing 1 according to the second embodiment of the invention. The braking element 240 rests against a portion of the inner ring 12 which is not in contact with the balls 10b, 10c. The oscillating mass 4 is for example screwed onto a thread 110 at the periphery of the outer ring 11.

FIG. 12 illustrates in perspective a suspension with an oscillating mass 4 mounted directly on the outer ring 11 of a ball bearing according to the second embodiment of the invention.

The balls 10a, 10b, 10c of the bearing 1 according to the invention can be replaced by rollers, cylinders or any type of elements used in bearings.

In the embodiments described, the balls 10a, 10b, and 10c are placed in notches 200a, 200b, 201b, 201c located on the outer face 20 of the segment 2, in contact with the outer ring 11 however, these notches 200a, 200b, 201b, 201c could be located on the inner face 24 of the segment 2, the balls 10a, 10b, and 10c then being in contact with the inner ring 12 of the bearing 1.

Reference numerals in figures [0079] I Ball bearing 10 Ball 10a Locking ball 10b Brake ball 10c Guide ball II Outer ring 12 Inner ring

Claims (15)

13 Cone 2 Segment 20 Outer side of segment 200a Lock notch 200b Notch of brake 2000 First portion 2001 Second portion 2002 Third portion 201a Notch of brake 201b Notch of brake 201c Notch of guide 2010 First portion 2011 Second portion 21 First end 22 Second end a Segment angular sector 24 Inner face of the segment 240 Braking element ß Angular sector of the braking element 241 Free end of the braking element 242 Distance 243 Slot 3 Teeth 4 Oscillating mass 5 Suspension of the oscillating mass 6 Unidirectional coupling claims Ball bearing (1) comprising an outer ring (11), an inner ring (12), balls (10a, 10b, 10c) and at least one segment (2) for separating said balls (10a, 10b, 10c) from each other, the segment (2) being placed, in the radial direction, between said inner ring (12) with which it is in contact and said outer ring (11), at least some of said balls (10) being moving relative to said segment (2) so as to occupy a different relative position according to the direction of rotation of said rings, characterized in that said segment (2) comprises a braking element (240), so that, in a first direction of rotation only, one of said rings (11, 12) can rotate independently of the other ring (11, 12) but being braked by said braking member (240). 2. Ball bearing (1) according to claim 1, said braking element (240) comprising a flexible blade in contact with said inner ring (12). 3. Ball bearing (1) according to the preceding claim, said segment (2) having at least one first notch (200a, 200b, 201a, 201b) in which a ball (10a, 10b) can move between a first position when the outer ring rotates in a first direction of rotation and a second position when the outer ring rotates in the second direction of rotation. 4. Ball bearing (1) according to claim 3, each segment comprising a first said notch (200b, 201a, 201b), said notch brake, arranged so that at least in a first direction of rotation, a said ball (10b), called the brake ball, presses on the segment (2) so as to press the braking element (240) against the inner ring (12) in order to create friction between the segment (2) and the ring interior (12). 5. Ball bearing according to claim 4, said brake notch (200b, 201a, 201b) being arranged to change the braking torque exerted against said inner ring (12) in the direction of rotation. Ball bearing according to Claim 5, arranged in such a way that each said segment (2) pivots on itself when the brake ball (10b) moves in the brake notch (201a, 200b), in such a way as to vary the pressure exerted by the braking element (240) on the inner ring (12). 7. Ball bearing (1) according to one of claims 3 to 6, each segment (2) having a second said notch, said locking notch (200a), arranged so that in a second direction of rotation, a said ball (10a), called the locking ball, is wedged between the outer ring (11) of the bearing (1) and the segment (2), making the outer ring (11) and the inner ring (12) integral in rotation. . 8. Ball bearing (1) according to the preceding claim, each locking notch (200a) being arranged so that in the second direction of rotation, said locking ball (10a) exerts a reduced pressure on the segment (2). ), so as to allow the outer ring (11) to rotate with respect to the segment (2) 9. Bearing (1) according to one of claims 7 or 8, arranged so that, when a locking ball (10a) rolls against a second portion (2001) of the locking notch (200a), a brake ball (10b) rolls against the second portion (2011) of the brake notch (201a, 201b), the braking member (240) being pressed against the inner race (12) and the rotational speed of the inner ring (12) being braked. 10. Ball bearing (1) according to one of claims 3 to 6, each segment (2) having a second said notch, said guide notch (201c), allowing said segment to rotate freely relative to said outer ring ( 11) in the second direction of rotation. 11. Ball bearing (1) according to one of claims 1 to 10, said braking element (240) being formed by a blade separated from the body of the segment (2) by a slot (243) allowing the blade to deform to compensate for machining tolerances. 12. Unidirectional coupling system (6) comprising a ball bearing (1) according to one of claims 1 to 11, an integral inlet in rotation with the inner ring (12), an output integral in rotation with the outer ring. (11), wherein in a first direction of rotation, the rotational movement of the input is not transmitted to the output and the rotational speed of the inner ring (12) and the outer ring (11) is reduced by the braking element (240) while in a second direction of rotation, the rotational movement of the input is transmitted to the output. 13. Automatic watch (7) comprising a unidirectional coupling system (6) according to the preceding claim, the input being kinematically connected to an oscillating mass (4) and the output being kinematically connected to a mainspring. 14. Suspension (5) oscillating mass comprising the ball bearing (1) according to one of claims 1 to 3 or 10 to 11. 15. Automatic watch comprising an oscillating mass (4) carried by the suspension (5) according to the preceding claim.