阅读说明：本技术 用于离合器摩擦盘的渐进装置及装有该装置的离合器摩擦盘 (Progressive device for a clutch friction disc and clutch friction disc fitted with such a device ) 是由 L.瓦西厄 D.勒吕 B.雷古斯基 于 2020-04-28 设计创作，主要内容包括：本发明涉及一种用于离合器摩擦盘的渐进装置(10),包括：具有旋转中心轴线(X)的支撑凸缘(11、11a),其中环形中央部分(12、12a)适用于与扭转振动阻尼器(2)配合,而外部部分(13、13a)支承逐渐接合叶片(20、20a),所述逐渐接合叶片在支撑凸缘的外部部分的配合区域(14、14a)和自由端部(21、21a)之间沿周向延伸,以及沿周向放置在支撑凸缘(11、11a)的两个面上的摩擦垫(30),所述摩擦垫分布在支撑凸缘的外部部分上。(The invention relates to a progressive device (10) for a clutch friction disc, comprising: a support flange (11, 11a) having a central axis of rotation (X), wherein the annular central portion (12, 12a) is adapted to cooperate with the torsional vibration damper (2), while the outer portion (13, 13a) bears a gradual engagement blade (20, 20a) extending circumferentially between a cooperating region (14, 14a) and a free end (21, 21a) of the outer portion of the support flange, and friction pads (30) placed circumferentially on both faces of the support flange (11, 11a) distributed on the outer portion of the support flange.)

1. A progression device (10) for a clutch friction disc, comprising:

a support flange (11, 11a) having a central axis of rotation (X), wherein the annular central portion (12, 12a) is adapted to cooperate with the torsional vibration damper (2) and the outer portion (13, 13a) bears gradually engaging vanes (20, 20a) extending circumferentially between a cooperating region (14, 14a) and a free end (21, 21a) of the outer portion of the support flange, and

Friction pads (30) placed circumferentially on both faces of the support flange (11, 11a), said friction pads being distributed on the outer portion of the support flange,

characterized in that on one of the faces of the support flange each friction pad (30) is fixed by two adjacent gradually engaging blades and covers the support flange engagement area (14, 14a) between the two gradually engaging blades (20, 20 a).

2. The progressive apparatus (10) according to claim 1, wherein, on the other face of the support flange, each friction pad (30) is fixed by two adjacent engagement areas (14, 14a) of the support flange (11, 11a) and covers the progressive engagement blade (20, 20a) located between the two engagement areas (14, 14 a).

3. The progressive apparatus (10) of claim 1 or 2, wherein the engagement zone (14, 14a) extends radially from the annular central portion (12, 12a) up to the outer portion (13, 13a) of the support flange.

4. The progressive apparatus (10) of any one of claims 1 to 3, wherein the engagement region (14, 14a) is planar and lies in the same plane as the central portion (12, 12a) of the support flange.

5. The progressive apparatus (10) of any one of claims 1 to 4 wherein each progressive engagement blade (20, 20a) comprises a planar support region (22, 22a) axially offset with respect to a central portion (12, 22a) of the support flange, and the support region (22, 22a) comprises apertures (23), some of the apertures (23) being dedicated to the fixing of a first friction pad and others of the apertures (23) being dedicated to the fixing of a second friction pad.

6. The progressive apparatus (10) according to any one of claims 1 to 5, wherein the progressive engagement blade (20a) is made in a single piece with the support flange (11a) starting from the mating zone (14 a).

7. The progressive apparatus (10) of claim 6, wherein the progressive engagement blade (20a) comprises, on its free end (21a), a support area (22a) in relation to two friction pads.

8. The progressive apparatus (10) of claim 7, wherein the progressive engaging blades (20a) are connected to the mating zone (14a) along a fold (24) extending radially up to the outer diameter (Db) of the outer portion, the fold (24) being located circumferentially between the support zone (22a) and the mating zone (14 a).

9. The progressive device (10) according to claim 8, wherein the fold (24) extends in orthogonal direction with respect to a central axis (X) of the support flange (11a) so that the fold (24) is pressed in isostatic manner under bearing stress.

10. The progressive apparatus (10) of any one of claims 1 to 5, wherein the progressive engagement blade (20) is attached and riveted to the support flange (11) at the mating region (14).

11. The progressive apparatus (10) of claim 10, wherein the progressive engagement blade (20) comprises at least two folds (24a, 24b) of material defining a support area (22) in relation to two friction pads (30), the two folds (24a, 24b) extending in orthogonal directions with respect to a central axis (X) of the support flange, such that the folds are pressed in an isostatic manner under bearing stress.

12. The progressive apparatus (10) of claim 11, wherein the folds (24a, 24b) of the same progressive engaging blade (20) are parallel to each other and have the same axial stiffness.

13. The progressive device (10) of any one of the preceding claims, wherein the free end (21, 21a) of the progressive engaging blade (20, 20a) is axially retained with respect to the support flange (11, 11a) by retaining means (50) when the progressive device is not subjected to all the compressive axial forces.

14. The progressive apparatus (10) of claim 13, wherein the retaining means (50) comprises a shoulder rivet (51), the shoulder rivet (51) being fixed to a support flange (11, 11a) cooperating with the free end (21, 21a) of the first progressive engaging blade, the first progressive engaging blade bearing on the shoulder of the rivet (51) when the progressive apparatus is not subjected to all compressive axial forces.

15. The progressive device (10) of claim 13, wherein the retaining device (50) comprises a folded tab (52), the folded tab (52) being formed by a first progressive engagement lobe and axially covering a second progressive engagement lobe, the free end (21, 21a) of the second progressive engagement lobe bearing on the folded tab (52) of the first progressive engagement lobe when the progressive device is not subjected to all compressive axial forces.

16. A clutch friction disc (1) for a motor vehicle, comprising: torque transmission flange (3), two drive washers (4) placed on either side of the torque transmission flange (3), a helical compression spring (5) bearing on the torque transmission flange and the drive washers, and a progressive device (10) according to any one of the preceding claims, wherein the support flange (11, 11a) is supported by one of the torque transmission flange (3) or the two drive washers (4).

Technical Field

The invention relates to a progressive device for a clutch friction disc of a motor vehicle. The motor vehicle may be a so-called industrial vehicle, which is for example a heavy goods vehicle, a public transport vehicle or an agricultural vehicle.

More specifically, the present invention relates to improvements in clutches which include clutch friction discs mounted on the input shaft of the gearbox and supported on the flywheel in a clutched position. A clutch mechanism (also known as a momentum wheel) fixed to the flywheel exerts a clamping force on the clutch plates to transfer the torque generated by the engine.

Background

Clutch discs typically include annular friction linings or pads formed as segments that are fixed to a support that is itself attached to the torque transmitting flange. The friction pads are typically of the cermet type.

Two drive washers placed on either side of the flange are mounted on a central hub that is firmly connected to the output shaft of the gearbox. A helical compression spring is circumferentially disposed between the washer and the flange. The transmission of torque and the filtering of the non-periodic behaviour of the engine are achieved by continuously compressing and releasing the spring.

In the clutch re-engagement phase, the transfer of torque must be as gradual as possible. The clutch mechanism then exerts an increasing compressive axial force on the progressive device until the engine torque has been fully transferred.

However, at this stage, the segment-shaped friction pads are subjected to great stresses and tend to deform in an uncontrolled manner, then generating discontinuities in the transmission of torque, which are accompanied by grip phenomena with extremely uncomfortable vibrations, which are harmful to driving the vehicle.

The progressive devices already exist comprising a friction pad in the form of a segment as described in particular in patent application EP3036451a 1.

This document discloses a clutch friction disc comprising in particular a torsional vibration damper and a progressive means. The progressive means are formed by friction pads in segments fixed on pairs of connected progressive engaging blades, each of which is attached at the periphery of the torque transmitting flange.

The progressive nature of the device is provided by the axial stacking of two blades, one acting as a support and the other having folds which deform radially when the clutch mechanism is closed. However, this configuration is not always satisfactory because it cannot effectively solve the above-described technical problem.

The drawbacks associated with this progressive arrangement are associated with the limited number of friction pads, which do not guarantee sufficient clutch durability. Since the friction surface is segmented, the contact pressure is greater than would normally be present if the friction surface were annular. As a result, wear on the friction surfaces of the clutch friction discs increases.

The number of folds available on the gradual engagement blades is also limited, so that the progressive arrangement has a high overall stiffness. Therefore, the vehicle comfort is degraded.

Disclosure of Invention

The object of the present invention is to overcome these technical problems by proposing an improved progressive device with progressively engaging vanes, the deformation of which is controlled by removing or at least greatly limiting the risk of non-parallelism of the friction pads during the clutch re-engagement phase.

To this end, the invention proposes a progressive device for a clutch friction disc, comprising:

A support flange having a central axis of rotation X, wherein the annular central portion is adapted to cooperate with the torsional vibration damper, while the outer portion bears gradually engaging vanes extending circumferentially between a cooperating region and a free end of the outer portion of the support flange, an

Friction pads placed circumferentially on both faces of the support flange, said friction pads being distributed over the outer portion of the support flange,

wherein each friction pad is fixed by two adjacent progressively engaging blades on one of the faces of the support flange, and each friction pad covers the support flange mating area between the two progressively engaging blades.

Such a progressive arrangement according to the invention has the advantage of increasing the friction surface of the clutch friction discs and thus improving the durability of the clutch, due to the friction pads placed on the support flanges.

The progressive arrangement according to the invention has the advantage of reducing assembly geometry failures and increasing the fixing points, as a result of the fixing of the friction pads on two adjacent progressive engaging blades, so that the centrifugal resistance of the clutch friction discs is improved.

Advantageously, on the other face of the support flange, each friction pad is fixed by two adjacent mating areas of the support flange and each friction pad covers the gradually engaging blade located between the two mating areas. In this way, the distribution of the friction pads on the two faces of the support flange is the same, thus contributing to an increase in the durability of the clutch.

Advantageously, the mating zone extends radially from the annular central portion as far as the outer portion of the support flange.

Preferably, the outer diameters of the central and outer portions of the support flange are radially offset and the radial offset is at least equal to the width of the progressively engaging vanes. In this way, the mechanical strength of the support flange and the gradual joining blade is improved, since the mating surface between these elements is enlarged.

Preferably, a friction pad adapted to cooperate with a friction surface of a clutch mechanism pressure plate is fixed on the gradual engagement blade, and a friction pad adapted to cooperate with a friction surface of a momentum wheel of the transmission system is fixed on an engagement area of the support flange. In this way, the progressive nature of the device is oriented in the direction of the clutch mechanism, thus contributing to improved vehicle comfort.

The invention may have one or other of the features described below in combination with each other or separately from each other:

the mating region may be planar and lie in the same plane as the central portion of the support flange;

the friction pad may have an angular segment shape;

the friction pad may be formed of a cermet material, a frit or an organic material;

the number of friction pads per friction face may be between 3 and 12;

The friction pads can be fixed by fixing rivets or welding;

each friction pad of the same friction face may partially cover, at an angle, two friction pads of the opposite friction face;

the friction pad may be adhered to the separator foil;

the friction pad may be adhered to a first separator foil and a second separator foil, the first and second foils being separate, wherein the first foil is supported on the first gradual engagement leaf and wherein the second foil is supported on the second gradual engagement leaf;

the foil may comprise holes for the passage of rivets to fix the pads on the support flange, and the associated friction pads may comprise holes arranged for the passage of fixing rivets;

the holes of the friction pads may be oblong;

each gradual engagement blade may comprise a planar support area axially offset with respect to the central portion of the support flange, and the support area may comprise apertures, some of which are dedicated to fixing the first friction pad and others of which are dedicated to fixing the second friction pad. For example, the support region may include four apertures, two of which are dedicated to securing a first friction pad and two of which are dedicated to securing a second friction pad;

the aperture of the support area can accommodate a rivet for fixing the friction pad on the gradual engagement blade;

The friction pads can be fixed together on an annular metal plate bearing directly on a planar support area which progressively engages the blades;

the free end of the gradual engagement blade is axially retained with respect to the support flange by the retaining means when the gradual means are not subjected to all the compressive axial forces;

the retaining means may comprise a shoulder rivet fixed on a support flange cooperating with the free end of the first gradual engagement blade, the latter bearing on the shoulder of the rivet when the progressive means are not subjected to all the compressive axial forces;

the shoulder rivet may fix a second gradual joining blade on the support flange, the second gradual joining blade being adjacent to the first gradual joining blade;

the retaining means may comprise a tab folded from the free end of the gradual engagement blade and placed in an opening provided in the support flange, the folded tab bearing on the support flange when the gradual means is not subjected to all the compressive axial forces;

the retaining means may comprise a folded tab formed by a first gradual engagement lobe and axially covering a second gradual engagement lobe, the free end of the second gradual engagement lobe bearing on the folded tab of the first gradual engagement lobe when the progressive means are not subjected to all the compressive axial forces.

According to another aspect of the invention, another subject of the invention is a progressive device having all or some of the aforementioned features, wherein the gradual joining blades are made in one piece with the support flange starting from the mating zone.

Preferably, the gradual-engagement blades may comprise, on their free ends, support areas in relation to the two friction pads.

An advantage of this further aspect of the invention is that the assembly of the progressive device is simplified, since the number of parts to be assembled is reduced. Assembly geometry failures are reduced by securing the friction pads to two adjacent progressive engagement blades.

Advantageously, the fold progressively engaging the blade, extending in a radial direction until the outer diameter of the outer portion, is connected to the mating region, the fold being located circumferentially between the support region and the mating region.

Preferably, the fold may extend in an orthogonal direction with respect to the central axis of the support flange, such that the fold is pressed in an isostatic manner under bearing stress.

Advantageously, the support area may be flat and comprise four apertures, two of which are dedicated to the first friction pad and two of which are dedicated to the second friction pad, thereby improving the planar quality of the friction face.

The mating region may include additional folds extending circumferentially opposite to the direction of gradual engagement with the blades such that the overall stiffness of the progressive device is reduced.

According to another aspect of the invention, another subject of the invention is a progressive arrangement having all or some of the aforementioned features, wherein the gradual joining blades are attached and riveted to the support flange at the mating region.

Preferably, the gradual engagement blades may comprise at least two folds of material delimiting support areas in relation to the two friction pads, the two folds extending in orthogonal directions with respect to the central axis of the flange, such that the folds are pressed in an isostatic manner under bearing stress.

An advantage of this further aspect of the invention is that, due to the increased number of folds, the mechanical strength of the progressive device is increased and its overall stiffness is reduced. Assembly geometry failures are reduced by securing the friction pads to two adjacent progressive engagement blades.

Advantageously, the support area may be flat and comprise four apertures, two of which are dedicated to the first friction pad and two of which are dedicated to the second friction pad, thereby improving the planar quality of the friction face.

Preferably, the folds of identical gradual-engagement blades may be parallel to each other and have the same axial stiffness.

Advantageously, the folds may have the same width and the same height and extend symmetrically on either side of the diametrical axis of the support flange.

The support flange may have a recess in the angular section below the support area gradually engaging the blade, improving the inertia of the gradual device.

The gradual-engagement blades may be made of a steel plate with the folds perpendicular to the rolling direction of the steel plate.

According to another aspect of the invention, another subject of the invention is a clutch friction disc for a motor vehicle, comprising: a torque transmitting flange, two drive washers placed on either side of the torque transmitting flange, a helical compression spring bearing on the torque transmitting flange and the drive washers, and a progressive arrangement having all or some of the foregoing features, wherein the support flange is supported by one of the torque transmitting flange or the drive washer.

The support flange may include a recess or window around the helical compression spring.

Drawings

The invention will be better understood from a reading of the following description, given by way of example only and with reference to the accompanying drawings, in which:

Figure 1 is an isometric view of a clutch friction disc fitted with a progressive device according to a first embodiment of the invention;

figure 2 is an exploded isometric view of the progressive means according to the first embodiment of the invention of figure 1;

figure 3 is a front view of the progressive device according to the first embodiment of the invention of figure 1;

figure 4 is a cross-sectional view of a progressive device according to the first embodiment of the invention of figure 1;

figure 5 is a partial view of a progressive device according to the first embodiment of the invention of figure 1;

figure 6 is an isometric view of a clutch friction disc fitted with a progressive arrangement according to a second embodiment of the invention;

figure 7 is an exploded isometric view of a progressive device according to the second embodiment of the invention of figure 6;

figure 8 is an exploded isometric view of a progressive device close to a third embodiment of the second embodiment of the invention;

fig. 9 is a cross-sectional view of a progressive device according to a fourth embodiment of the invention;

fig. 10 is a cross-sectional view of a progressive device according to a fifth embodiment of the invention;

fig. 11 is a section of a progressive device according to a sixth embodiment of the invention;

fig. 12 is a section view of a progressive device according to a seventh embodiment of the invention.

Detailed Description

The remainder of the description and claims will use, in a non-limiting manner and for the sake of easy understanding, the terms "front" or "rear" according to a direction relative to an axial orientation determined by the main axis O of rotation of the transmission of the motor vehicle and the terms "inner/inner" or "outer/outer" relative to the axis O and in a radial orientation orthogonal to said axial orientation.

Fig. 1 and 5 show a first embodiment of a clutch friction disc 1 fitted with a progressive device 10 according to the invention.

A clutch friction disc 1 having an axis of rotation X comprises a torsional vibration damper 2 in which are typically disposed a torque transmitting flange 3, a drive washer 4 and a helical compression spring 5. In this case, the clutch discs have a so-called "symmetrical" architecture and also comprise progressive means 10 attached to the torque-transmitting flange 3. Two drive washers 4 are placed on either side of the torque transfer flange 3, capturing the helical compression spring 5 in the separate housing.

A clutch mechanism fixed to a flywheel (not shown) exerts a clamping force on the clutch discs 1 to transmit the torque generated by the engine in the direction of the gearbox.

The engine torque enters the clutch disc through the progressive device 10 and returns through the central hub 6 between the two drive washers 4. The central hub 6 is connected to the drive washer 4 by a rivet. The central hub 6 is mounted on the output shaft (not shown) of the gearbox and transmits the engine torque through splines 7 formed on its internal bore.

As shown in fig. 1 and 2, according to a first embodiment of the invention, the progressive device 10 comprises a support flange 11 with a central rotation axis X borne by the torque transmission flange 3, progressively engaging blades 20 and friction pads 30 angularly distributed according to the axis X on the periphery of the torque transmission flange 3.

The support flange 11 comprises an annular central portion 12 suitable for cooperating with the torsional vibration damper 2 and an outer portion 13 bearing the gradual engagement blades 20. The gradual engagement blades 20 are attached and extend circumferentially around the support flange 11. Each gradual joint blade is fixed to the mating zone 14 of the support flange 11. The mating region corresponds to a support flange portion defined by a generally rectangular surface. As shown in fig. 5, the mating region 14 is located on the outer portion 13 of the support flange 11. The gradual engagement blades 20 extend circumferentially from this mating region up to a free end 21. There are as many mating areas 14 on the support flange 11 as there are gradual engagement blades 20.

The mating region 14 extends radially from the annular central portion 12 as far as the outer portion 13 of the support flange. In this case, the outer diameter Da of the central portion is located radially inside the friction pad. Thus, the outer diameter Db of the central portion 12 and the outer portion of the support flange is offset in the radial direction and this radial offset is at least equal to the width of the progressively engaging vanes 20.

The support flange 11 comprises a window 17 surrounding the helical compression spring 5. A window 17 is formed in the central portion 12. The support flange 11 is secured to the torque transfer flange 3 using rivets (not shown) which are inserted into holes 19, the holes 19 being formed in the central portion 12 and angularly disposed between the windows 17.

The friction pad 30 has an angular segment shape and completely covers the friction surfaces of the clutch friction disc 1. In this example, each friction face is formed by eight separate friction pads 30. In order to increase the durability of the clutch. The friction pad 30 is formed of a cermet material. However, the friction pad may also be formed of glass frit, ceramic, or organic material. The friction pad 30 adheres to the separation foil 31 for reasons of mechanical strength. In this example, the friction pad is a sub-assembly formed by two separate layers of material, the separation foil 31 typically being made of steel.

As shown in fig. 1 and 2, a friction pad 30 adapted to cooperate with a friction surface of a clutch mechanism pressure plate is secured to the progressive engagement blade 20, and a friction pad adapted to cooperate with a friction surface of a flywheel of the transmission system is secured to the engagement region 14 of the support flange.

The friction pads 30 are placed circumferentially on both faces of the support flange 11 and distributed on the outer portion 13. Each friction pad is held by two adjacent progressively engaging blades on the face of the support flange oriented in the direction of the clutch mechanism, and each friction pad covers the support flange engagement region 14 between the two progressively engaging blades 20.

On the other face of the support flange oriented in the direction of the flywheel, each friction pad is fixed by two adjacent mating areas 14 of the support flange 11 and covers the progressively engaging blade between the two mating areas. Thus, each friction pad of the same friction face angularly partially covers both friction pads of the opposite friction face. The friction pads 30 of the two friction surfaces are offset by 45.

In a variant not shown, the friction pads may be adhered to the first and second separator foils. The foils of the same mat are separate. The first foil is supported on the first gradual engagement tab and the second foil is supported on the second gradual engagement tab.

The separating foil 31 comprises holes 32 for the passage of rivets to fix the pads on the support flange, and the associated friction pad 30 comprises holes 33 arranged for the passage of fixing rivets. The hole 33 of the friction pad has a rectangular shape.

Each gradual engagement blade includes a planar support region 22 that is axially offset relative to the central portion 12 of the support flange 11. The support area 22 comprises four apertures 23, of which two apertures 23 are dedicated to fixing a first friction pad and two further apertures 23 are dedicated to fixing a second friction pad.

In the embodiment shown in fig. 1 to 5, the gradual-engagement blades 20 are rigidly connected and fixed by rivets 8 to the support flange 11 by at least one of their ends. At least two folds of material 24a, 24b are provided on these gradual engagement blades, which delimit the support area 22 in relation to the two friction pads. The two material folds 24a, 24b extend in orthogonal directions with respect to the radial axis X of the support flange 11, so that under bearing stress the folds are pressed in an isostatic manner. The orthogonal direction may be defined as being orthogonal with respect to the rotation axis X, in particular perpendicular to a radius for mounting the blade 20 on the flange 11.

The gradual-engagement blades are made of a steel plate, and the folded portions 24a, 24b are perpendicular to the rolling direction of the steel plate. Preferably, the folds of the same blade are parallel to each other.

Once the gradual-engagement blades 20 have been riveted to the support flange 11, the support area 22 raises the height of the folds 24a, 24b with respect to the plane of the support flange 11 formed by the central portion 12. The overall rigidity of the progressive device 10 is improved due to the presence of a large number of folds.

In this example, the folds 24a, 24b have the same width and the same height and extend symmetrically on either side of the diametrical axis of the support flange.

The support flange also has a notch 25 in the angular section below the support area 22 that gradually engages the blade. The notch 25 provides the rivet 8 with an axial housing for fixing the blade and limits the overall inertia of the progressive means 10.

The gradual engagement blades 20 have a generally rectangular shape with a flat end 26 with straight edges and a free end 21. The gradual-engagement blades 20 are fixed on the mating area of the support flange 11 by at least one of these ends, preferably by a straight end 26, as shown in fig. 5. The free end 21 ends in a spatula 28, the spatula 28 being freely overlying the outer portion 13 of the support flange 11.

The straight edge planar end 26 of the gradual engagement blade 20 is adjacent to one of the two folds 24a, 24 b.

According to an aspect of the invention, the two folds 24a, 24b form the same arc. The fold is inclined at an angle of between 1 ° and 20 ° with respect to a plane perpendicular to the central axis X. The inclination of the folds provides a height of between 0.5 and 1.5mm, preferably 0.9mm, relative to the support area 22 of the central portion 12 of the support flange 11.

The geometry and profile of the folds are defined such that the mechanical stresses generated in the blade remain within the elastic range of the material of which they are made.

Thus, during the clutch re-engagement phase, when at least one friction face is subjected to bearing stresses, the bearing stresses are transmitted to the support region 22 and the folds 24a, 24b, the folds 24a, 24b then being deformed in a controlled manner.

More precisely, the two folds are pressed in the same direction on all the blades 20 in the same and simultaneous manner, like a universal joint, resulting in a tangential angular offset of the friction pads, the friction faces of which nevertheless remain in parallel planes, as shown in fig. 1. In this way, the fold is pressed in an isostatic manner.

This selective deformation of the folds 24a, 24b of the support region 22 allows the friction pads 30 of the friction surfaces oriented in the direction of the clutch mechanism to pivot freely about the rotation axis X relative to the friction surfaces oriented in the direction of the flywheel.

Thus, the friction pad remains in a plane perpendicular to the axis X.

Referring now to fig. 6 and 7, a clutch friction disc 1 equipped with a progressive means 10 according to a second embodiment of the invention will be described, in which the progressive engagement blades 20a are made in a single piece with the support flange 11a starting from the mating zone 14 a.

In this case, the clutch friction discs have a so-called "asymmetric" architecture, in which the progressive means 10 is attached to one of the drive washers 4. The progressive means are placed outside the torsional vibration damper 2.

The engine torque enters the clutch disc through the progressive means 10, passes through the drive washer 4, then through the helical compression spring 5, and finally exits through the central hub 6 fixedly connected to the torque transmission flange 3.

A central hub 6 is mounted on the output shaft of the gearbox (not shown) and transmits engine torque through splines 7 formed on the internal bore of the torque transmitting flange 3. In this case, the central hub 6 and the torque transmission flange 3 form one and the same piece.

As shown in fig. 6 and 7, according to this second embodiment of the invention, the progressive means 10 comprise a support flange 11a with a central rotation axis X, borne by one of the two drive washers 4, a progressive engagement blade 20a and friction pads 30 angularly distributed according to the axis X on the periphery of the torque transmission flange 3.

The support flange 11a comprises an annular central portion 12a suitable for cooperating with the torsional vibration damper 2 and an outer portion 13a bearing the progressive engagement blades 20 a. The gradual engagement blades 20a are made in a single piece with the support flange 11 a.

The support flange 11a comprises a recess 18 surrounding the helical compression spring 5. A recess 18 is formed in the inner bore of the central portion 12 a. The support flange 11a is fixed to the drive washer 4 using rivets (not shown) inserted into holes 19, the holes 19 being formed in the central portion 12a and angularly disposed between the notches 18.

In the embodiment shown in fig. 6 and 7, the gradual-engagement blade 20a comprises a support area 22a on its free end 21 a.

Each gradual engagement blade extends circumferentially from the mating region 14a of the support flange 11 a. The mating region corresponds to a support flange portion defined by a substantially rectangular surface. As shown in fig. 7, the mating region 14a is located on the outer portion 13a of the support flange 11 a. There are as many mating areas 14a on the support flange 11a as there are gradual engagement blades 20 a.

A fold 24, which gradually engages the blade and extends in the radial direction until the outer diameter Db of the outer portion 13a is connected to the mating region, is located circumferentially between the support region 22a and the mating region 14 a.

Preferably, the fold 24 extends in an orthogonal direction with respect to the central axis X of the flange, so that the fold 24 is pressed in an isostatic manner under bearing stress.

Similar to the first embodiment of the present invention, the support area 22a is associated with two friction pads 30.

The friction pads 30 are circumferentially placed on both faces of the support flange 11a and distributed on the outer portion 13 a. On the support flange face oriented in the direction of the clutch mechanism, each friction pad is fixed by two adjacent gradually engaging blades, and each friction pad covers the support flange 11a fitting area 14a between the two gradually engaging blades 20 a.

Advantageously, the support area 22a is planar and comprises four apertures 23a, two of which 23a are dedicated to the first friction pad and two of which 23a are dedicated to the second friction pad, so that the planar quality of the friction faces is improved.

The fitting region 14a also comprises an additional fold 29 extending circumferentially opposite to the direction of gradual engagement of the blade 20a, so that the overall rigidity of the progressive arrangement is reduced.

Referring now to fig. 8, a clutch friction disc 1 incorporating a progressive addition device 10 according to a third embodiment of the invention will be described, the third embodiment being substantially similar to the second embodiment except that the friction pads 30 are fixed together on an annular plate 40. The annular plate 40 supports the friction pad 30 by the separator 31 and bears directly on the planar support area 22a which gradually engages the blade 20 a.

The progressive addition device 10 may comprise an annular sheet 40 on each of the two faces of the support flange, so as to improve the resistance of the progressive addition device to centrifugal forces.

Fig. 9 shows a fourth embodiment of a progressive device 10 according to the invention. This fourth embodiment differs from the one disclosed with reference to fig. 1 in that the free end 21 of the progressive engaging blade is axially retained with respect to the support flange 11 by the retaining means 50 when the progressive means are not subjected to all the compressive axial forces.

The retaining means 50 comprise a shoulder rivet 51 fixed to the support flange 11 and cooperating with the free end 21 of the first gradual engagement blade, which bears on the shoulder of the rivet 51 when the progressive means are not subjected to all the compressive axial forces.

Fig. 10 shows a fifth embodiment of a progressive device 10 according to the invention. This fifth embodiment differs from the embodiment disclosed with reference to fig. 9 in that the shoulder rivet 51 secures the second gradual engagement lobe directly to the support flange 11, the second gradual engagement lobe being adjacent to the first gradual engagement lobe.

Thus, at the same time, the shoulder rivet 51 fixes the second progressive engaging blade on the support flange 11 and axially retains the free end 21 of the first progressive engaging blade, which bears on the shoulder of the rivet 51 when the progressive means are not subjected to all the compressive axial forces.

Fig. 11 shows a sixth embodiment of a progressive addition device 10 according to the invention. This sixth embodiment differs from the embodiment disclosed with reference to fig. 1 in that the retaining means 50 is formed by the cooperation of two gradually engaging blades 20.

The retaining means 50 comprise a folded tab 52, formed by a first gradual engagement lobe and axially covering a second gradual engagement lobe, the free end 21 of which bears on the folded tab 52 of the first gradual engagement lobe when the progressive means are not subjected to all the compressive axial forces.

Fig. 12 shows a seventh embodiment of a progressive addition device 10 according to the invention. This seventh embodiment differs from the embodiment disclosed with reference to fig. 1 in that the retaining means 50 are formed directly by the gradual engagement blades 20.

The retaining means 50 comprise a tab 53 which is folded from the free end 21 of the gradual engagement blade 20 and placed in an opening 54 arranged in the support flange 11. The folded tab 53 bears on the support flange when the progressive device is not subjected to all compressive axial forces.

The present invention is not limited to the above-described exemplary embodiments.