The pulley of the document D1 includes an integral rim of a first power transmission member (a belt connected to a motor for example), a bell integral with a second power transmission member (a shaft of an alternator e.g. ), in particular through a hub, one of the power transmission members being driving and the other being driven, and a torsion spring centered inside of the bell.

The rim includes a driving abutment adapted to cooperate with the torsion spring in a first direction of relative rotation between the rim and the bell.

The bell comprises a first bell abutment for limiting the angle of rotation (α-ι) between the rim and the bell in the first direction of relative rotation between the rim and the bell. This bell also comprises a second bell abutment for limiting the angle of rotation (eu) between the rim and the bell in a second relative direction of rotation between the rim and the bell, this second direction of rotation being opposite the first direction relative rotation between the rim and the bell.

More specifically, the torsion spring includes a first end and a second end arranged so that, in the first direction of relative rotation, the first end of the torsion spring engages the bell and the second end of the torsion spring engages the rim drive abutment for the closing spring on the bell until the second end of the torsion spring abuts against the first abutment bell. The angular position of the abutment bell defined then a maximum deflection angle (α-ι) of the first end of the spring in the first relative direction of rotation between the rim and the bell.

This situation is encountered for example when the rim, driving, for example the fact that the belt is connected to a start-up phase motor drives the bell conducted by closing of the torsion spring and then abutted.

This is seen in Figure 1.

1 shows the principle of operation of such a pulley as described in document D1. More specifically, it shows the variation of the torque transmitted between the rim and the bell in response to changing of the angle between the rim and the bell. The origin of the angle corresponds to a boundary position between a bias of the torsion spring and lack of bias of the torsion spring.

In the portion where the angle is negative, the torque increases gradually as the torsion spring closes in the bell, thus allowing the transmission of torque between the rim and the bell and therefore between the two transmission elements power. Once the maximum deflection angle (α-ι) reached, the abutment thus ensures a very high torque transfer.

Decelerating, and from the stop position corresponding to the maximum deflection angle (α-ι), the rim and the bell then rotate in the second direction of relative rotation, the torsion spring relaxes in the bell until reaching its neutral position. From this neutral position, the torque between the rim is the bell is zero (residual friction near). Depending on its level of deceleration, the rim can then continue its journey (user coasting), in relation to the bell, until the driving abutment of the rim or possibly another abutment of the rim, comes into contacting the second stop bell.

then hit another maximum deflection angle (had). This is what is shown in the right part of Figure 1 where the constant torque region and the effect of the abutment at the other maximum deflection angle is observed (eu).

The device proposed in D1 works perfectly.

However, the acceleration of the rim relative to the bell may be important. The abutment at the maximum deflection angle (α-ι) generates repeated shocks which may affect the life of the pulley. A similar situation can be met for another maximum deflection angle (had). This is particularly the case for certain motor vehicles for which, engine start-up, acceleration and deceleration related to the first engine combustion cycles are very high.

These repeated shocks can also cause loosening of the pulley on the power transmission element, for example on the alternator.

An object of the invention is to provide a decoupling pulley not having at least one of the aforementioned disadvantages.

To this end, the invention provides a decoupling pulley provided with a longitudinal axis, said pulley comprising:

- a rim comprising a first zone for receiving a belt connecting the rim to a first power transmission member, and a second zone situated in the axial extension, i.e. in the direction defined by the longitudinal axis of the pulley, of the first zone;

- a hub secured to a second power transmission member; one of the power transmission members being driving and the other being carried out;

- a ring having a first portion located below the second area of ​​the rim and a second portion in the form of at least a cylindrical skirt extending from the first portion, along said longitudinal axis, said crown being rotatable with respect to the rim and to the hub about said longitudinal axis;

- means for driving of the ring relative to the rim;

- an elastically deformable element, for example a torsion spring centered on the hub, a first end secured to the hub and a second end is attached to the ring;

said at least one cylindrical skirt being also located vis-à-vis the elastically deformable element, so that the elastically deformable element may come in contact with said at least one cylindrical skirt.

The pulley according to the invention may also exhibit at least one of the following characteristics, taken alone or in combination:

- said at least one cylindrical skirt of the ring is elastic; - said at least one cylindrical skirt of the ring comprises a plurality of longitudinal slots and accordingly a plurality of parts separated from each other by one of the slots;

- at least one slot of said plurality of slots has a width, measured on a circumference of said at least one cylindrical skirt, strictly less than a width of at least a portion of the cylindrical skirt;

- at least slot of said plurality of slots has a width, measured along the circumference of said at least one cylindrical skirt of greater than or equal to a width of at least a portion of the cylindrical skirt;

- the ring is made of a material selected from plastics such as polyamide, polyester, polyoxymethylene, polyetheretherketone, polyphenylene sulfide, or alloys thereof or thermoplastic elastomers;

- the second part of the crown is in the form of two concentric cylindrical skirts, the elastically deformable member being located between the two cylindrical skirts;

- means to ensure, in a first rotational direction relative displacement between the rim and the hub, the drive of the crown by the rim comprises at least one abutment on the inner periphery of the rim, at the second zone and at least one stop located on the outer periphery of the crown, at the first portion; - - the inner periphery of the rim comprises at least one second abutment and the outer periphery of the ring comprises at least a second stop;

- means to ensure, in a first rotational direction relative displacement between the rim and the hub, the drive of the crown by the rim comprises a one-way clutch, for example a torsion spring, whose one end is fixed to the crown and whose remaining part is mounted both in the second zone of the rim and around the crown;

- means to ensure, in a first rotational direction relative displacement between the rim and the hub, the drive of the crown by the rim comprise a unidirectional free wheel mounted on the one hand, to force to the second zone of the rim and on the other hand, around the first portion of the crown;

- the pulley comprises at least one bearing located between the rim and the hub;

- said at least one bearing includes a radially extending face and in contact with the hub;

- said at least one bearing is formed either by a plastics material selected from polyetheretherketone, poly (ethylene terephthalate), polyamide laden with molybdenum disulfide (MoS 2 ), the polyamide reinforced polytetrafluoroethylene or polyoxymethylene or with a inner metal layer or a metal alloy, covered by an outer layer of polytetrafluoroethylene loaded;

- the pulley provides a cover fixedly mounted on the rim and preferably in contact with the crown.

The invention will be better understood and other objects, advantages and features thereof will appear more clearly from reading the following description which is made with reference to the following appended figures:

Figures 2 to 10 show a first embodiment of a decoupling pulley according to the invention, according to various embodiments;

Figures 1 1 to 18 show a second embodiment of a decoupling pulley according to the invention, according to various embodiments;

Figures 19 and 20 show a third embodiment of a decoupling pulley according to the invention;

Figures 21 and 22 show block diagrams of the first embodiment of the invention, according to various embodiments;

Figures 23 and 24 show block diagrams of the second embodiment of the invention, according to different variants.

A first embodiment of the invention is described with reference to Figures 2 to 10.

The decoupling pulley 100 according to the invention comprises a rim 1 attached to a first power transmission member (not shown, e.g. a belt connected to a shaft of a vehicle engine, leading). The rim 1 is provided with a first zone 1 1, external, for receiving a belt, in this case a poly V® belt type to make the connection with the first power transmission member and a second zone 12 located in the axial extension, i.e. in the direction defined by the longitudinal axis AX of the pulley, of the first zone 1 1.

The rim 1 is also provided with at least one stop 13, 14 on the inner periphery of the rim 1 at the second region 12. Such a stop 13, 14 is also called internal stop.

Advantageously, and as shown in Figures 2 to 10, the rim is provided with at least two stops 13, 14 on the inner periphery 1 10 of the rim 1, always at the second zone 12 of the rim 1.

The pulley 100 also includes a hub 2 fixed to a second power transmission member (e.g., a shaft of an alternator, driven).

One of the power transmission elements is leading and the other is conducted.

The pulley 100 also comprises a ring 3, 30.

The crown 3, 30 comprises a first portion 31 located under the second zone 12 of the rim and a second portion 32 being in the form of at least a cylindrical skirt 35, 36 extending from the first portion 31 , along said longitudinal axis AX. Specifically, in Figures 2-8, the second portion 32 is in the form of two cylindrical skirts 35, 36 concentric. In contrast, in Figures 9 and 10, which represent an embodiment variant of the pulley 100 shown in the previous figures, a single cylindrical skirt 35 is provided.

It should be noted that the first part 31 of the ring is more rigid than the second portion 32 of the crown. This is related to the geometry of each of the two parts 31, 32, as is apparent from the appended figures, and in particular the fact that the second part 32 comprises a free end, at the opposite of its anchoring area in the first part 31.

The crown 3, 30 also comprises at least one stop 33, 34 on the outer periphery 330 of the ring 3, at the first part 31. Such a stop 33, 34 is also called external abutment. Advantageously, and as shown in Figures 2 to 10, the ring 3 is provided with at least two stops 33, 34 located on the outer periphery 330 of the ring, always at the first part 31 of the ring 3.

The pulley 100 is also provided with an element 4 is elastically deformable in this case and by way of example a torsion spring 4, fixed both to the hub 2 by a first end 41 and to the ring 3 by a second end 42.

The torsion spring 4 is centered inside of the hub 2. For this purpose, the hub 2, as any conventionally envisaged hub for decoupling pulleys comprises an annular zone ZA is possible to center the spring 4 of twist, this ZA annular zone being delimited by two walls, namely the wall P1, radially inner, and the wall P2, radially externally of the hub 2.

Furthermore, the or each cylindrical skirt 35, 36 of the ring 3 is inserted between the torsion spring 4 and the hub 2. In particular, when two cylindrical skirts 35, 36 are provided, the spring 4 of twist is advantageously housed between the two cylindrical skirts 35, 36, the latter being themselves housed between two walls P1 and P2 of the hub 2.

When two cylindrical skirts 35, 36 are provided, the spring retainer 4 twisting the hub 2 and the ring 3, 30 can be effected by a recess or by forms of restraint, provided in the hub 2 and the ring 3, 30. in figures 2-8, the end 42 of the torsion spring 4 is mounted recessed in a housing 331 of the ring provided for this purpose, in order to receive an end 42 of curved shape, that is i.e. extending radially. Figures 9 and 10, the end 42 of the torsion spring is not bent and therefore comes into contact with a shape-retaining (not visible in the figs 9 and 10) of the ring 3.

When two cylindrical skirts 35, 36 are provided, four of the torsion spring is located between the two cylindrical skirts 35, 36.

The or each cylindrical skirt 35, 36 is located vis-à-vis the elastically deformable element 4.

The ring 3 is centered on the hub 2. The ring 3, 30 is also rotatable relative to the hub 2 about the longitudinal axis AX of the pulley 100. The spring 4 provides a resilient torsion link between the hub 2 and the ring 3.

The ring 3 is also mounted in the rim 1 and, more particularly, the first part 31 of the ring 3, 30 is located under the second zone 12 of the rim so that the ring 3 is rotatable with respect to the rim 1 about said longitudinal axis AX of the pulley 100. This can be easily accomplished by providing a clearance between the outer periphery 330 of the ring 3, 30 and the inner periphery 1 10 of the rim 1.

Means are however provided for driving of the ring 3, by the rim 30 1. This is a mechanical connection formed by said at least one internal abutment 13, 14 of the rim 1 and said at least one external abutment 33, 34 of the ring 3, 30. The driving of the ring 3, 30 by the rim 1 can indeed be provided by means of these stops. In operation, this training is not always implemented, according to the stresses to which the driving element. This will be explained in more detail subsequently, especially in support of Figures 7 and 8.

The pulley 100 also includes at least one bearing 6 located between the rim 1 and the hub 2.

The bearing 6 ensures relative rotation of the rim 1 to the hub 2. For this purpose, the bearing 6 is advantageously made of a plastic material selected from polyetheretherketone (PEEK), poly (ethylene terephthalate) (PET), polyamide (PA) in charge of molybdenum disulfide (MoS 2 ), polyamide (PA) loaded polytetrafluoroethylene (PTFE) or polyoxymethylene (POM). Alternatively, the bearing 6 is formed with a metal layer or a metal alloy, covered by a layer charge of polytetrafluoroethylene (PTFE). These materials have a low friction coefficient.

The bearing 6 includes a face 62, radially internal, extending longitudinally (along the axis AX) and in contact with the hub 2 and a face 63, radially outer, longitudinally extending and in contact with the rim 1. Advantageously, the bearing 6 also has a face 61 extending radially, i.e. substantially perpendicularly to the faces 62 and 63 and in contact with the hub 2. This face 61 facilitates the assembly and holding in place the bearing 6.

The pulley 100 includes a cover 8. The cover 8 is intended to cover the rim 1, on the side opposite the zone 1 1 for receiving the belt. Advantageously, the cover 8 is mounted in contact with the ring 3, 30 and more exactly the side face 37 of the ring 3, 30 which faces the cover 8.

The hood 8 is associated with a sealing plug 9.

The pulley 100 finally comprises a seal 10 from a side opening OL of the rim 1, the side opposite the sealing plug 9, to provide a seal.

As for the crown, more design alternatives can be considered.

Thus, in Figure 4, there is shown a ring 3 which said at least one cylindrical skirt 35, 36 of the ring 3 is elastic. In this case, the two skirts 35, 36 are resilient concentric. It is then understood that the first portion 31 of the crown is so much more rigid than the second portion 32 of the crown, in that the second portion 32 (cylindrical skirt) is then rendered elastically deformable.

For this spring, several possibilities are conceivable. In Figure 4, said at least one cylindrical skirt 35, 36 of the ring 3, in this case each cylindrical skirt 35, 36, comprises a plurality of slots F1, F2, F3, respectively F'1, F'2, longitudinal F'3 and accordingly a plurality of portions P1, P2, P3, ΡΊ, P'2, P'3 separated from each other by one of the slots. F1 slot is required to leave a passage for the end 42 of the torsion spring 4 to the housing 331. However, this slot F1 also makes it possible, in combination with the other slots to provide the desired elasticity for the or each cylindrical skirt 35, 36. The ring 3 of Figure 4 is that shown in Figures 2, 3 and 6-8.

However, the presence of at least a cylindrical skirt 35, 36 elastic is not necessary within the framework of the invention.

One can thus provide at least a cylindrical skirt 35, 36 of ring 30 having no elasticity. This is what is shown in Figure 5. In this figure 5, there are no slots, with the exception of the slot F1, to pass the curved end 42 of the torsion spring 4 to the housing 331.

Of course, in the case where the end 42 of the torsion spring is not bent, such a slot F1 is not necessary when

a non-elastic ring 30 is envisaged. This is what can be seen in Figures 9 and 10. However, we can quite provide, in the case of the variant of Figures 9 and 10, a crown, the cylindrical skirt conforms to the cylindrical skirt 35 of the ring 3 shown in FIG 4 and in this case, each slot F1, F2, F3 only intervenes to provide an elastic behavior to the relevant skirt. It may even provide, in another variant, the same crown to that of the ring 3 of Figure 4.

We will now describe the operation of the pulley 100 in the case of operation of the elastically deformable member 4 in the closed (Figures 2 to 8, the presence of a bent end for the element 4 is elastically deformable) of one hand to a crown 3 non-resilient cylindrical skirt in support of Figure 21 and, secondly, to a crown 3 non-resilient cylindrical skirt.

For the purposes of explanation, we describe the case where the rim 1 is driving and the hub 2 is carried out.

Figure 21 (case of a non-elastic cylindrical skirt) represents the evolution of the torque transmitted between the rim 1 and the hub 2, according to the angle formed between the rim 1 and the hub 2. The origin of the angle (zero angle) corresponds to a boundary position between a biasing element

4 elastically deformable and an absence of biasing of the same element 4 (at least over a certain range of values, as explained subsequently).

Starting from the zero angle position, the rim 1 is rotated clockwise (arbitrary convention in Figure 7, coupling mode). This may correspond to a status of acceleration, for example when starting an engine.

An internal abutment 13, 14 of the rim 1 is then brought into contact, via its face 13, 14a, with an external stop 33, 34 of the ring 3, 30. The rim 1 then drives the crown 3, 30 to rotate in clockwise. Since the element 4 is elastically deformable, in this case a torsion spring is attached to both the ring 3, 30 and also, to the hub 2, the ring 3 then drives the hub 2 by means of element 4 is elastically deformable, also clockwise. In Figure 21, this translates into a torque rise in the negative angle zone between the zero angle and the angle R1. The couple then goes from zero to the value C 0 (Zero angle) corresponding to the friction torque between the hub 2 and the bearing 6. Then, it increases linearly as and that the elastically deformable element 4 is biased.

If the deformation of the elastically deformable element 4 is sufficiently large, it will then come into contact with one of the cylindrical skirt 35, 36, in this case the cylindrical skirt of smaller diameter, i.e. the skirt cylinder 36 (since in this example, the elastically deformable element 4 works closure: figures 2 to 8 with the presence of a bent end 42). This contact angle is defined by R1 in Figure 21.

Beyond R1 angle, the torque increases faster than below the R1 angle, because the contact between the element 4 is elastically deformable and the cylindrical skirt 36 provides additional torque.

It is in this operation to the point R2. Between points R1 and R2, the contact area between the elastically deformable element and the cylindrical skirt 36 is increasing. This is for example the case when the elastically deformable element 4 is a torsion spring as in this case, more and more turns of the torsion spring 4 come into contact with the cylindrical skirt 36 as and as the angle increases (in absolute values).

In point R2, the element 4 is elastically deformable can no longer be deformed and is completely blocked by the cylindrical skirt 36. For example, in the event that the elastically deformable element 4 is a torsion spring, this corresponds to a situation where all internal surfaces 44 of the spring turns are in contact with the cylindrical skirt 36. from point R2, the torque from the wheel rim 1 to the hub 2 thus passes through the first portion 31 of the ring 3 and the overall, while rigid, formed both by the element 4 is elastically deformable and the cylindrical skirt 36. This point R2 corresponds to the configuration of the pulley January 00 shown in Figure 7.

Unlike the pulley of the prior art (D1), there is no free abutment.

Moreover, when the document D2 (DE1 0201 520 561 2), the placing in contact of the element 4 is elastically deformable with the cylindrical skirt does not involve straining means for driving of the ring relative to the rim. This is due to the fact that the first part 31 of the ring is more rigid than the second portion 32. This improves the life of the pulley January 00.

If the pulley January 00 undergoes a deceleration (engine stop or deceleration phase during such engine start), it then traverses the curve of Figure 21 in the other direction until reaching the zero angle. During this return to the zero angle, the internal stops 1 3, 14 and external 33, 34 remain in contact under the action of the resisting torque of the hub 2 and the elastically deformable element 4 which naturally seeks to return to its position balance.

If the deceleration is strong enough, we will then be in the area of ​​positive angles.

More specifically, from the zero angle, the internal stops

1 3, 14 and external 33, 34 are no longer in contact and the rim 1 performs a relative rotational movement with respect to the ring 3 which is anticlockwise (arrow F2 in Figure 8).

Between the zero angle and the angle R3, the torque is constant, due to the absence of stress of the element 4 is elastically deformable. This torque is, however, not null and the rim 1 consists of friction on the bearing 6 which is added the friction between the cover 8 (attached to the rim 1) and the face 37 of the ring 3. Incidentally the zero angle, the torque thus passes from the value C 0 to the value Ci (with | Ci |> C 0 , because the cap / crown friction is added to the bearing friction linked). The contact force between the ring 3 and the cover 8 is generated by an axial prestressing element 4 is elastically deformable. This preload can be

flexible depending on the desired level Ci. It should be noted that the friction between the cover 8 and the face 37 of the ring 3 is then used to decelerate faster the hub 2, if one relied only between the zero angle and the angle on R30 the only friction bearing / hub. This is particularly interesting because the overspeed the hub 2 with respect to the rim 1 generates noisiness phenomena that can thus limit.

Of course, when the cover 8 is not in contact with the ring 3, so that torque C would be equal to C 0 . There would be no contribution friction cap / crown.

From the R3 angle, internal stops 13, 14 and external

33, 34 come again into contact with the faces 13b, 14b of the internal stops of the rim 1.

This contact will hinder the anti-clockwise movement of the rim 1, aided by a power-biasing member 4 elastically deformable. This translates into a decrease in the torque between the angles of R3 and R4 in Figure 21. Indeed, under the effect of this stress, the elastically deformable element 4 will be deformed, but opening until it comes into contact with the cylindrical skirt of greater diameter, namely the cylindrical skirt 35. The area of contact between the element 4 is elastically deformable between the corners increases R3 and R4, thus increasing more and more torque (braking effect).

WE CLAIMS

1. Pulley (100, 100 ', 100 ") of decoupling provided with a longitudinal axis (AX), said pulley comprising:

- a rim (1) comprising a first zone (1 1) for receiving a strap connecting the rim to a first power transmission member, and a second zone (12) situated in the axial extension, i.e. in the direction defined by the longitudinal axis (AX) of the pulley, of the first zone

(1 1 ) ;

- a hub (2) integral with a second power transmission member;

one of the power transmission members being driving and the other being carried out;

- a ring (3, 3 ') having a first portion (31) situated under the second zone (12) of the rim and a second portion (32) being in the form of at least a cylindrical skirt (35, 36 ) extending from the first portion (31) along said longitudinal axis (AX), said ring (3) being rotatable with respect to the rim (1) and the hub (2) about said longitudinal axis (AX);

- means (5; 50; 13, 14, 33, 34) for driving the ring (3) relative to the rim (1);

- an elastically deformable element (4), eg a torsion spring centered on the hub (2), a first end (41) is fixed to the hub (2) and a second end (42) is secured to the crown (3);

said at least one cylindrical skirt (35, 36) being also located vis-à-vis the elastically deformable element (4) so ​​that the elastically deformable member (4) can come into contact with said at least a cylindrical skirt (35, 36).

2. Pulley (100, 100 ', 100 ") of claim 1, wherein said at least one cylindrical skirt (35, 36) of the ring (3) is elastic.

3. Pulley (100, 100 ', 100 ") according to the preceding claim, wherein said at least one cylindrical skirt (35, 36) of the ring (3) comprises a plurality of slots (F1, F2, F3) and longitudinal accordingly a plurality of portions (P1, P2, P3) separated from each other by one of the slots.

4. Pulley (100, 100 ', 100 ") according to the preceding claim, wherein at least one slot (F1, F2, F3) of said plurality of slots has a width, measured on a circumference of said at least one cylindrical skirt (35, 36) is strictly less than a width of at least a portion (P1, P2, P3) of the cylindrical skirt (35, 36).

5. Pulley (100, 100 ', 100 ") according to one of Claims 3 or 4, wherein at least slot (F1, F2, F3) of said plurality of slots has a width, measured over the circumference of said at least a cylindrical skirt (35, 36) greater than or equal to a width of at least a portion (P1, P2, P3) of the cylindrical skirt (35, 36).

6. Pulley (100, 100 ', 100 ") according to one of the preceding claims, wherein the ring (3, 3') is made of a material selected from plastics such as polyamide (PA), polyester, polyoxymethylene (POM), polyetheretherketone (PEEK), polyphenylene sulfide (PPS) or alloys thereof or thermoplastic elastomers (TPE).

7. Pulley (100, 100 ', 100 ") according to one of the preceding claims, wherein the second portion (32) of the crown (3, 3') is in the form of two cylindrical skirts (35, 36 ) concentric, the elastically deformable element (4) being located between the two cylindrical skirts.

8. Pulley (100) according to one of the preceding claims, wherein the means (13, 14, 33, 34) for, in a first rotational direction relative displacement between the rim (1) and the hub (2), the drive of the ring (3) by the rim (1) comprises:

- at least one stop (13, 14) on the inner periphery (1 10) of the rim (1), at the second zone (12);

- at least one stop (33, 34) on the outer periphery (330) of the ring (3, 3 ') at the first portion (31).

9. Pulley (100) according to the preceding claim, wherein:

- the inner periphery of the rim (1) comprises at least one second stop (14); and

- the outer periphery of the ring (3) comprises at least one second stop (34).

10. Pulley (100 ') according to one of claims 1 to 7, wherein the means (5) for providing, in a first rotational direction relative displacement between the rim (1) and the hub (2), the drive of the ring (3) by the rim (1) comprises a unidirectional clutch (5), eg a torsion spring, one end (51) is secured to the crown (3) and the remaining part (52) is mounted both in the second zone (12) of the rim (1) and around the ring (3).

January 1. Pulley (100 ") according to one of claims 1 to 7, wherein the means (5) for providing, in a first direction of relative rotation between the rim (1) and the hub (2), the drive of the ring (3) by the rim (1) includes a freewheel (50) mounted unidirectional one hand, force with the second region (12) of the rim (1) and on the other hand, around the first part (31) of the ring (3).

12. Pulley (100, 100 ', 100 ") according to one of the preceding claims, comprising at least one bearing (6) between the rim (1) and the hub (2).

13. Pulley (100, 100 ', 100 ") according to the preceding claim, wherein said at least one bearing (6) comprises a face (61) extending radially and in contact with the hub (2).

14. Pulley (100, 100 ', 100 ") according to one of claims 12 or 13, wherein said at least one bearing (6) is achieved either by a plastics material selected from polyetheretherketone (PEEK), poly ( ethylene terephthalate) (PET), polyamide (PA) loaded into molybdenum disulfide (M0S 2 ), polyamide (PA) loaded polytetrafluoroethylene (PTFE) or polyoxymethylene (POM) or with a metallic inner layer or alloy metal, covered with an outer layer loaded polytetrafluoroethylene (PTFE).

15. Pulley (100, 100 ', 100 ") according to one of the preceding claims, wherein there is provided a cover (8) fixedly mounted on the rim (1) and preferably in contact with the ring (3, 3 ').

16. Pulley (100, 100 ', 100 ") according to one of the preceding claims, wherein the first portion (31) of the ring is more rigid than the second portion (32) of this ring.