FR3059066A1 - CLUTCH FRICTION DISC AND CLUTCH COMPRISING SUCH A DISK - Google Patents

Abstract

The invention relates to a clutch friction disk comprising a support disc (120) adapted to be mounted around a central rotation shaft and a plurality of blades (131) individually fixed one after the other on a face (121) of said support disc, each blade (131) comprising - a fixed end zone (131a), by which the blade is fixed on the support disc, and - a free end zone (131b), the free end zone (131b) of each progressive blade comprising at least one anchor (200) adapted to be housed between the support disk (120) and the fixed end zone (131b) of a next neighboring blade ( 131-i). The invention also relates to a clutch, particularly for a motor vehicle, comprising such a friction disk.

Description

TECHNICAL AREA

The present invention relates to a clutch friction disc fitted with a set of progressive blades, one end of each blade of which is fixed to the support disc and the other end of which is held under the neighboring blade. The invention also relates to a clutch comprising such a friction disc. The invention finds applications in the field of motor vehicle clutches and, in particular, in the field of motor vehicle clutches.

STATE OF THE ART

In the field of motor vehicle clutches, it is known to use a friction disc to transmit the torque between the engine and the gearbox. A conventional clutch friction disc comprises a support disc of sheet steel carrying on each of its faces a friction lining constituted by a thick disc of friction material.

In known manner, these friction linings are intended to be clamped between the pressure and reaction plates of the clutch. These clutch plates are linked in rotation to an engine shaft (the engine crankshaft in an application to the motor vehicle), while the friction disc is locked in rotation, by means of its hub, on a driven shaft ( the input shaft of the gearbox in an application to the motor vehicle). In the engaged position, the pressure plate ensures the adhesion of the friction disc on the reaction plate. In the clutch release phase, the pressure plate releases the friction linings, which disengages the motor shaft from the gearbox driven shaft.

In the re-clutch phase, the linings are highly stressed and tend to deform in an uncontrolled manner, thus creating discontinuities in the transmission of the torque which are accompanied by a phenomenon of chattering with very uncomfortable jolts and prejudicial to the driving of the vehicle.

To limit this chattering phenomenon, it is known to fix progressive blades on a first face of the support disc. An example of a friction disc comprising such progressive blades is shown in FIG. 1. According to this example, the friction disc 100 comprises:

a support disk 120 having a first face 121 and a second face 122,

a set 130 of progressive blades 131, more simply called blades, fixed on the first face 121 of the support disc,

a first friction lining 140 and a second friction lining 150 mounted, respectively, on the first face 121 and the second face 122 of the support disc, and

- a foil 110 fixed on the first friction lining 140 and mounted between the progressive blades 131 and said first lining.

The elements mentioned above which form the friction disc, namely the support disc, the progressive blades, the friction linings and the foil, are coaxial around an axis of rotation X.

The progressive blades 131 of the assembly 130 are positioned one after the other on an annular zone of the support disk 120. Each blade 131 has a fixed end zone, by which the blade 131 is individually fixed on the disk. support 120, a free end zone 131b, which is free from any fixing, and a central zone 131c by which the blade 131 is fixed on the first friction lining 140. Each blade 131 has a cambered shape intended to compensate, by crushing, the deformations of the friction linings in order to maintain the two friction linings 140, 150 in parallel planes.

Such a configuration thus offers gentle progressiveness, in the re-clutch phase. However, this configuration has drawbacks in the presence of centrifugal effects. In fact, to allow them to be crushed, the progressive blades 131 have a fine thickness relative to the thickness of the support disc 120. Consequently, the free end region 131b of the blade is sensitive to any stress and pressure. It is therefore sensitive to centrifugal effects. Thus, under the effect of centrifugal forces generated by the rotation of the motor, the free end region of the blades is raised, causing mechanical stress in the first friction lining or even a deformation of said first lining. An example of the effects of centrifugal forces on the friction disc 100 is shown in Figures 2A and 2B. More specifically, FIGS. 2A and 2B represent the axial displacements, in millimeters, of the elements constituting the friction disc 100, respectively, when the engine is not running (zero rotation speed) and when the engine is running at a speed of 7000 rpm / min. These figures show that under the effect of the centrifugal forces generated by the rotating motor, the blades 131 move axially, causing traction - that is to say mechanical stress - within the materials of the friction lining.

However, if this centrifugal mechanical stress applied to the friction linings exceeds the allowable stress rate, the friction linings may break, damaging the entire clutch

SUMMARY OF THE INVENTION

To respond to the problem mentioned above of the centrifugal mechanical stress in the friction linings, the applicant proposes a friction disc in which the free end of each progressive blade is anchored under the neighboring blade so as to limit the lifting of said free end.

The axial displacement of a part of a blade along the axis of rotation X of the clutch friction disc is called "lifting".

According to a first aspect, the invention relates to a clutch friction disc comprising a support disc capable of being mounted around a central rotation shaft and a plurality of blades individually fixed one after the other on one face. of said support disk. Each blade includes

- a fixed end zone, by which the blade is fixed to the support disc, and

- a free end zone.

The friction disc is characterized in that the free end zone of each progressive blade has at least one anchor capable of being housed between the support disc and the fixed end zone of a next neighboring blade.

The "anchor" is a part attached to or cut out in the free end area of the blade, and intended to be inserted under the neighboring blade to limit the axial displacements of the free end of the blade. The "neighboring blade" is the blade which is contiguous to a given blade in the annular zone of the support disc.

The expression “neighboring blade” means for the contiguous blade according to the given blade in the direct direction of transmission from the engine to the gearbox, the neighboring blade preceding the given blade in the direct direction of transmission of the engine being named “ previous neighbor blade ”.

The anchoring of each blade under the neighboring blade makes it possible to limit the lifting of the free end of the blade while allowing the other displacements necessary for the progressiveness function of said blade.

Advantageously, the anchor of each blade is located on one side of the blade opposite the next adjacent blade. In this way, each blade is anchored under the next neighboring progressive blade.

According to some embodiments, the anchor is a retaining tab cut out in the free end region of the blade. These embodiments make it possible to manufacture the anchor in the same cutting step as that of the blade.

Advantageously, when the support disc has recesses, the anchor is positioned in one of these recesses, said recess then forming a housing for receiving the anchor. Thus housed in a recess in the support disc, the anchoring does not generate any excess thickness in the friction disc.

According to certain variants, when the progressive blade is fixed to the support disc 20 by at least two rivets, the anchoring of the preceding neighboring blade is positioned in an interval between the two rivets. The anchor is then anchored at an optimal location in which the lift of the blade's end zone is minimal.

According to other variants, the fixed end zone of the progressive blade has an overhang under which the anchor of the preceding neighboring blade is housed. This projection may be a projecting cut made in one side of the fixed end region of the blade. The existence of an overhang offers a wider range of blade shapes and anchors, the shape and dimensions of the overhang being able to adapt to the shape and dimensions of the anchors.

Advantageously, when the anchor is a retaining tab, the retaining tab comprises at least one ply of material ensuring a negative drop within the retaining tab. This negative drop makes it possible to insert, without deforming it, the holding tab under the neighboring blade.

According to a second aspect, the invention relates to a clutch, in particular for a motor vehicle, comprising:

- a reaction plate intended to be fixed in rotation on a driving shaft,

- a friction disc as defined above, which carries friction linings and which is intended to be locked in rotation on a driven shaft,

- A pressure plate capable of pressing the friction disc on the reaction plate, and îo - elastic means with axial action acting on the pressure plate.

BRIEF DESCRIPTION OF THE FIGURES

Other advantages and characteristics of the invention will appear on reading the description, illustrated by the figures in which:

- Figure 1, already described, shows an exploded view of a friction disc according to the state of the art;

- Figures 2A and 2B, already described, show internal movements of the friction disc, depending on the speed of rotation of the engine;

- Figure 3 shows a perspective view of an example of progressive blades mounted on a support disc of the friction disc according to the present invention;

- Figures 4A and 4B show, respectively, a sectional view of a portion of the friction disc according to the invention and an enlargement of a portion of Figure 4A;

- Figure 5 shows a top view of a portion of friction lining with, in transparency, a progressive blade;

- Figure 6 shows, in a top view, an embodiment of the anchoring of the progressive blades;

- Figure 7 shows, in a top view, another embodiment of the anchoring of the progressive blades;

- Figures 8A and 8B show comparison curves of displacements and stresses within a friction disc according to the prior art and according to the invention.

DETAILED DESCRIPTION OF AT LEAST ONE EMBODIMENT

An exemplary embodiment of a friction disc, in which the free end of each progressive blade is held under the neighboring blade, is described in detail below, with reference to the accompanying drawings. This example illustrates the characteristics and advantages of the invention. It is however recalled that the invention is not limited to this example.

In the figures, identical elements are identified by identical references. For reasons of readability of the figures, the size scales between the elements represented are not respected.

Traditionally, the friction disc has a support disc and progressive blades. The support disc, of axis of rotation X, has an outer radial zone provided with progressive blades and a central orifice delimited by an inner radial zone ensuring the connection to a hub (not shown in the figures).

The hub is mounted on the driven shaft of the gearbox and is connected to the support disc by a set of peripheral teeth meshing in slots (not visible in the figures) formed on the inner radial zone of the central orifice.

In the engaged position, a pressure plate applies a tightening force to the friction disc so as to transmit the torque produced by the engine to the gearbox.

The friction disc further comprises two friction linings, produced in the form of attached crowns and fixed on either side of the support disc. The first friction lining engages the pressure plate of the clutch mechanism while the second friction lining bears on the flywheel in the engaged position. To increase its stiffness and its lifespan, the first friction lining is fixed, for example by gluing, on an intermediate foil, itself fixed on the first face of the support disc by means of progressive blades. The second friction lining is in turn directly fixed to the second face of the support disc, for example by gluing.

An example of a support disc 120 on which progressive blades 131 are mounted in accordance with the invention is shown in FIG. 3. These progressive blades 131, cut from a thin sheet, are angularly distributed around the periphery of the support disc 120, in the outer radial area 120a of the support disc 120. The progressive blades 131 thus form, in the outer radial area of the support disc, a ring having an outer contour 130a substantially coinciding with the periphery of the support disc 120 and a internal contour 130b.

As shown in FIGS. 3 and 4A-4B, each blade 131 has a fixed end zone 131a, a free end zone 131b and a central zone 131c. Each blade 131 is joined and fixed to the outer edge 120a of the support disc 120 by its fixed end zone 131a by means of rivets 132. The central zone 131c of each blade 131 is fixed, for example by rivets 132, to the first lining 140 by means of foil 110 on which the first lining 140 is bonded. The free end zone 131b of each blade is free to fix, that is to say that it is not fixed to any element. friction disc.

On each of the blades 131, are formed at least two plies of material 133a, 133b delimiting, respectively, the fixed end zone 131a of the central zone 131 this the free end zone 131b of the central zone 131c. When the blade 131 is fixed on the support disc 120 and on the first lining 140, the central zone 131c is raised by the height of the folds 133a, 133b relative to the plane of the support disc 120.

The free end zone 131b has an anchor 200 adapted to be housed under the fixed end zone 131a of the neighboring blade 131, that is to say of the next blade in the outer radial zone 120a. Of course, the anchor 200 of the preceding neighboring blade is adapted to be housed under the blade 131. This anchor 200 can be in several forms, in particular in the form of a retaining tab which will be described later.

In certain embodiments of the invention, the anchor 200 of each blade

131 is housed in a recess 122 of the support disc 120. In fact, as shown in FIG. 1, the support disc 120 has several recesses adapted to accommodate the anchor 200 and limit the axial size of the system. In some embodiments of the invention, the blades 131 are positioned on the support disc 120 so that the fixed end region 131a of each blade 131 faces a recess 122 of the support disc. Thus, the anchor 200 of a blade 131 can be inserted into a recess 122. The recess 122 then constitutes a housing for receiving the anchor. Thus, as shown in FIGS. 4A-4B, the anchor 200 does not modify the relative flatness of the blades. It therefore does not modify the crushing properties of progressive blades. In other words, when the engine rotation speed is zero, the presence of the anchor 200 does not modify the distances between the surface of the support disc 120 and the blades 131 and therefore has no effect on the disc of friction. On the other hand, at non-zero engine speed, the anchoring has the effect of maintaining the free end of the blades, thereby limiting the lifting of said free end.

FIG. 5 represents a top view of a portion of friction disc. This representation shows, in the foreground, in solid lines, the first friction lining 140 and the support disc 120, and, by transparency, in dotted lines, a blade 131. This blade 131 has a substantially rectangular shape with an internal side. 134a and a rear side substantially with a straight edge, an external side 134c with a beveled edge and a cut front side 134d. This cut side 134d is the border of the free end zone 131b containing the anchor 200. In the example of FIG. 5, the anchor 200 is therefore a piece cut from the sheet of the blade 131.

Those skilled in the art will however understand that the anchor 200 can also be an independent part of the blade 131, attached and fixed to the blade 131 everywhere known means of fixing.

As shown in Figure 5, the blade 131 and the first friction lining 140 both have holes 136 provided to be aligned and thus receive rivets 132 of appropriate dimensions. These rivets 132 make it possible to fix the central zone 131c of the blade 131 on the first lining 140, through a foil 110.

In certain embodiments, and as shown in dotted lines in FIG. 5, the central zone 131c of the blade can comprise an H-shaped cut which makes it possible to control the deformation of the central zone 131c of the blade, in particular during the phases of re -clutch.

As mentioned above, the anchor 200 can take several forms. In certain embodiments, the anchor 200 is a retaining tab cut out in the free end region of each blade 131, as shown in FIG. 6. For example, the retaining tab 200 can be in the form of a flat hook , in the shape of a T or half T, or in any other form allowing the free end of a blade to be anchored with the neighboring blade. In the example of FIG. 6, the retaining tab 200 comprises a leg 210 secured to the free end zone 131b and a foot 220 capable of being anchored under the neighboring blade 131-i. The retaining tab 200 further comprises one or more plies of material 230 produced at the junction between the leg 210 and the free end region 131b of the blade. This / these folds 230 make it possible to generate a negative drop between the free end zone 131b and the underside of the neighboring blade 131-i by which the foot 220 of the retaining tab can be anchored under the neighboring blade 131- i.

In the representation of FIG. 6, the retaining tab 200 is shown above the neighboring blade 131-i, for reasons of readability of the figure. However, a person skilled in the art will understand that it is actually positioned below the fixed end zone 131 ai of the neighboring blade 131-i, in the same way as the retaining tab 200-i is inserted under the blade 131-j and that the retaining tab 200-k is inserted under the blade 131.

In certain embodiments, as shown in FIG. 6, the retaining tab 200 is adapted to be inserted under the neighboring blade, in the interval between the rivets 132 for fixing the fixed end zone 131a to the disc- support 120. A person skilled in the art will understand that the retaining tab 200 can be inserted at any location of the fixed end of the neighboring blade, but that an insertion close to at least one of the rivets 132 makes it possible to limit the deformations of the retaining tab and therefore of ensuring a firmer maintenance of the free end of the blade.

In certain embodiments, the fixed end 131a of each blade may include an overhang 300 under which the retaining tab 200 is housed. The overhang 300 is a projection of the fixed end region 131a of the blade formed on the rear side 134b or the internal side 134a of the blade. The overhang 300 may be a protruding cutout on one of the sides of the fixed end zone or else an insert and fixed on one of these sides. In the example of FIG. 7, the overhang 300-i of the neighboring blade 131-i is a protruding cutout on the internal side 134a-i of the blade 131-i, under which the retaining tab 200 of the blade 131. As in FIG. 6, the retaining tab 200 is shown above the neighboring blade ίο

131-i for reasons of readability of the figure. Those skilled in the art will however understand that the retaining tab is actually positioned below the overhang 300-i for the reasons mentioned above.

In the example of FIG. 7, the overhang 300-i being on the internal side of the blade 131-i, the retaining tab 200 is cut in the free end zone 131b near the internal side 134a of the blade 131. Other locations of the overhang 300, for example the middle of the rear side 134b of the blade (example of FIG. 6) and other locations and shapes of the retaining tab 200 can of course be envisaged, provided that the retaining tab has a positioning and a shape adapted to the positioning and the shape of the overhang 300.

Whatever the embodiment, the anchor 200 of each blade 131 extends the free end zone 131b of the blade as far as below the fixed end zone 131a of the neighboring blade so that the free end of each blade mounted on a support disc is held by the neighboring blade. Thus anchored under the neighboring blade, the free end of the blades is limited in axial displacement, which makes it possible to reduce, or even avoid, the lifting of the blade against the first friction lining and, therefore, reduce the mechanical stress in said first lining. .

Examples of displacement curves of the free end of the blade, with and without the anchor, are shown in Figure 8A. Curve C1 represents the displacement of the free end of a conventional blade, therefore without anchoring, as a function of the speed of rotation of the motor. Curve C2 represents the displacement of the free end of a blade of the friction disc of the invention, therefore with anchoring, as a function of the speed of rotation of the engine. These curves show that, beyond a motor rotation of 2000 rpm, the anchoring of the friction disc of the invention makes it possible to reduce the axial displacement of the free end of the blade and that the gain, in terms of axial displacement, is significant from 4000 RPM.

Examples of stress curves exerted on the first friction lining by the free end of a blade, with and without anchoring, are shown in Figure 8B. The curve C3 represents the stress exerted on the first lining by a conventional blade, therefore without anchoring, as a function of the speed of rotation of the engine. Curve C4 represents the stress exerted on the first lining by a blade of the friction disc of the invention, therefore with anchoring, as a function of the speed of rotation of the engine. These curves show that from 1500-2000 RPM, the stress on the friction lining is less when the blade is fitted with an anchor and that the difference in stress is significant from 4000 RPM. These curves also show that at 7000 rpm, the admissible stress rate C5 is not reached by the curve C4 while it is reached and even exceeded by the curve C3, which means that at 7000 rpm min, the friction lining is not damaged when the blades of the friction disc are fitted with anchors.

Thus, the friction disc which has just been described makes it possible to reduce the mechanical stress generated by the blades, in the presence of centrifugal effects, in the friction linings and therefore to maintain the friction linings in an optimal state.

According to a second aspect, the invention relates to a motor vehicle clutch which comprises a reaction plate intended to be wedged in rotation on a driving shaft, a friction disc carrying friction linings and intended to be wedged in rotation on a driven shaft, a pressure plate capable of pressing the friction disc on the reaction plate, elastic means with axial action acting on the pressure plate and a friction disc as described above. Such a friction disc provides the clutch friction linings with a longer service life than that of a conventional clutch.

Although described through a certain number of examples, variants and embodiments, the friction disc and the clutch according to the invention include various variants, modifications and improvements which will be obvious to those skilled in the art, being understood that these variants, modifications and improvements form part of the scope of the invention, as defined by the claims which follow.

Claims (9)

1. Clutch friction disc comprising a support disc (120) capable of being mounted around a central rotation shaft and a plurality of fixed blades (131) 5 individually, one after the other, on one face (121) of said support disc, each blade (131) comprising - a fixed end zone (131a), by which the blade is fixed to the support disc, and a free end zone (131b), characterized in that the free end zone (131b) of each progressive blade has at least one anchor (200) capable of being housed between the support disc (120) and the fixed end zone (131b) of a next neighboring progressive blade (131-i). 2. Clutch friction disc according to claim 1, characterized in that 15 the anchor (200) of each progressive blade is located on one side (134d) of the blade (131) opposite the next neighboring blade (131-i). 3. Clutch friction disc according to claim 1 or 2, characterized in that the anchor (200) is a retaining tab cut out in the end zone 20 free (131b) of the progressive blade. 4. Clutch friction disc according to any one of claims 1 to 3, in which the support disc (120) has recesses (122), characterized in that the anchor is positioned in one of the recesses of the support disk, said 25 recess forming a housing for receiving the anchor. 5. Clutch friction disc according to any one of claims 1 to 4, characterized in that, each progressive blade (131) being fixed on the disc support by at least two rivets (132), the anchoring is positioned in interval 30 between the two rivets. 6. clutch friction disc according to any one of claims 1 to 4, characterized in that the fixed end zone (131b) of the progressive blade has an overhang (300) under which is housed the anchor ( 200) of the previous neighboring blade (131-k). 7. A clutch friction disc according to claim 6, characterized in that the 5 overhang (300) is a projecting cut made in one side (134d) of the fixed end zone of the progressive blade. 8. clutch friction disc according to any one of claims 3 to 7, characterized in that the retaining lug (200) comprises at least one ply of ïo material (230) ensuring a negative drop within the lug holding. 9. Clutch, in particular for a motor vehicle, comprising: - a reaction plate intended to be fixed in rotation on a driving shaft, - a friction disc (100) carrying friction linings (140, 150) and 15 intended to be locked in rotation on a driven shaft, a pressure plate capable of pressing the friction disc on the reaction plate, and - elastic means with axial action acting on the pressure plate, characterized in that the friction disc (100) conforms to any one of the 20 claims 1 to 8. 1/4 130 131c / 131a CM CM