PROGRESSIVITY DEVICE FOR A CLUTCH FRICTION DISK, AND FRICTION DISK COMPRISING SUCH A DEVICE

Abstract

The invention relates on the one hand to a progressivity device for a clutch friction disk, comprising a progressivity web (1) having a central rotation axis (X), having on one face of its external rim (1a) a series of blades (2) on which are configured at least two deformable pleats (20a, 20b) delimiting a region (20) intended to support a first friction lining (G1) and equipped with a stiffness element, and on the other face a second friction lining (G2) fastened symmetrically to the first lining (G1), wherein the stiffness element comprises at least one tab projecting below the region (20), one end of which is intended to come into abutment against the web (1) upon deformation of the pleats (20a, 20b), limiting the arching of the region (20); and on the other hand to a friction disk comprising such a device.

Claims

1. A progressivity device for a clutch friction disk, comprising a progressivity web (1) having a central rotation axis (X), having on one face of its external rim (1 a) a series of blades (2) on which are configured at least two deformable pleats (20a, 20b) delimiting a region (20) intended to support a first friction lining (G1) and equipped with a stiffness element, and on the other face a second friction lining (G2), wherein said stiffness element comprises at least one tab (200) projecting below said region (20), one end of which is intended to come into abutment against the web (1) upon deformation of the pleats (20a, 20b), limiting the arching of said region (20).

2. The progressivity device according to claim 1, wherein said tab (200) is delimited by a cutout.

3. The progressivity device according to claim 2, wherein said cutout is H-shaped.

4. The progressivity device according to claim 3, wherein it comprises two identical tabs (200a, 200b) extending symmetrically with respect to the radial center axis of the support region (20).

5. The progressivity device according to claim 1, wherein said tab (200) is flanked by two longitudinal slots and extends tangentially to the web (1).

6. The progressivity device according to claim 1, wherein said tab (200) extends at rest at an inclination (β) of between 1° and 20° with respect to the plane of the support region (20).

7. The progressivity device according to claim 1, wherein said tab is located between the two pleats (20a, 20b).

8. The progressivity device according to claim 1, wherein the arching height of the tab (200) is less than or equal to the arching height of the support region (20).

9. The progressivity device according to claim 1, wherein said blades (2) are applied and riveted on the external rim (1a) of the web by means of at least one of their ends (2a).

10. The progressivity device according to claim 1, wherein the pleats (20a, 20b) extend in an orthoradial direction with respect to the central axis (X) of the web, so that under abutment stresses the pleats are compressed isostatically.

11. The progressivity device according to claim 1, wherein the pleats (20a, 20b) are parallel and have the same axial stiffness.

12. The progressivity device according to claim 1, wherein the pleats (20a, 20b) have the same width and the same height (h), and extend symmetrically on either side of the diametrical axis of the web (1).

13. The progressivity device according to claim 1, wherein said pleats (20a, 20b) are constituted by three segments (201, 202, 203) inclined at an angle (α) of between 1° and 20° with respect to the plane perpendicular to the central rotation axis (X) of the web.

14. The progressivity device according to claim 1, wherein said support region (20) is provided with a radial recess (20d) extending between the two pleats (20a, 20b).

15. A clutch friction disk (D), wherein it comprises a progressivity device according to claim 1.

16. The progressivity device according to claim 2, wherein said tab (200) extends at rest at an inclination (β) of between 1° and 20° with respect to the plane of the support region (20).

17. The progressivity device according to claim 3, wherein said tab (200) extends at rest at an inclination (β) of between 1° and 20° with respect to the plane of the support region (20).

18. The progressivity device according to claim 4, wherein said tab (200) extends at rest at an inclination (β) of between 1° and 20° with respect to the plane of the support region (20).

19. The progressivity device according to claim 5, wherein said tab (200) extends at rest at an inclination (β) of between 1° and 20° with respect to the plane of the support region (20).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0042] FIGS. 1A and 1B are overall perspective views of a first embodiment of a friction disk comprising the progressivity device according to the present invention, respectively as an exploded view and after assembly of the various components.

[0043] FIG. 1C is a perspective view of a first variant embodiment of the progressivity device according to the invention.

[0044] FIGS. 2A and 2B are respectively an enlarged frontal view and a section view along II-II of a blade used in the variant of the device according to the invention as illustrated by FIGS. 1A and 1C.

[0045] FIGS. 3A and 3B are schematic partial section views (without the rivets or web) of the progressivity device according to the invention, respectively at rest and in a re-engagement phase.

[0046] FIG. 4A is a partial exploded perspective view of another embodiment of a friction disk comprising a second variant of the progressivity device according to the invention, as depicted in perspective in FIG. 4B.

[0047] FIGS. 5A and 5B are respectively a frontal view and a section view along V-V of a blade used in the second variant embodiment of the device according to the invention of FIGS. 4A and 4B.

[0048] FIGS. 6A and 6B are schematic partial section views (without the rivets) of the second variant embodiment of the progressivity device according to the invention as illustrated by FIGS. 5A and 5B, respectively at rest and in a re-engagement phase.

[0049] FIGS. 7A and 7B are respectively a frontal view and a section view along VII-VII of a blade used in a third variant embodiment of the device according to the invention.

[0050] FIG. 8 is a perspective view of a fourth variant of the progressivity device according to the invention.

[0051] FIG. 9 is a graph comparing the displacements of linings under stress, with blades respectively according to the first variant of the device according to the invention (FIGS. 2A, 2B—curve 1) and according to the second variant in which said blades are equipped with an additional stiffness element (FIGS. 7A, 7B—curve 2).

[0052] For greater clarity, identical or similar elements are labeled with identical reference characters in all the Figures.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S)

[0053] The embodiments illustrated in the Figures presented above are of course provided only as non-limiting examples. Provision is explicitly made that these different embodiments and variants can be combined with one another so as to propose others.

[0054] FIGS. 1A and 1B illustrate a first embodiment of an improved friction disk comprising the progressivity device according to the invention.

[0055] This friction disk D comprises, in traditional fashion, an annular progressivity web 1 with a central rotation axis X having an external rim 1a equipped with a series of applied blades 2 intended to support peripheral friction linings, and a central orifice 10 delimited by an internal rim 1b ensuring connection to a hub M (FIG. 1B).

[0056] Blades 2 are distributed angularly over the periphery of web 1, around rotation axis X.

[0057] A clutch mechanism fastened on the engine flywheel (not depicted) applies a clamping force onto friction disk D in order to transmit the torque produced by the engine.

[0058] The two friction linings are implemented in the form of applied rings G1, G2 that are fastened on either side of web 1, as illustrated in FIG. 1A.

[0059] Friction hub M is mounted on the driven shaft of the gearbox and is connected to web 1 by a set of peripheral teeth meshing into slots (not visible in the Figures) configured on internal rim 1b of central orifice 10.

[0060] First lining G1 comes into engagement with the pressure plate of the clutch mechanism (not depicted), while second lining G2 comes into abutment against the engine flywheel in the engaged position.

[0061] Two guide washers 4 arranged on either side of web 1 are mounted on the central hub, capturing compression springs C in intercalated receptacles (FIG. 1B).

[0062] In order to increase its stiffness and service life, first friction lining G1 here is adhesively bonded to an intercalated shim 3 that is in turn fastened onto one face of web 1, while second friction lining G2 is fastened directly onto the other face of web 1 by adhesive bonding, as illustrated in FIG. 1A.

[0063] In the embodiment of FIGS. 1A and 1C, blades 2 are integrated and fastened onto external rim 1a of web 1, at at least one of their ends, by means of rivets R. Configured on these blades are at least two pleats 20a, 20b of material delimiting a support region 20 of first friction lining G1.

[0064] Once blades 2 have been riveted to web 1, support region 20 becomes elevated by an amount equal to the height of pleats 20a, 20b with respect to the plane of the web.

[0065] Support region 20 is preferably planar, and is equipped here with four orifices 22 intended to receive rivets R for fastening lining G1.

[0066] Blades 2 are substantially rectangular in shape, with one planar end 2a having a straight edge and one beveled end 2b, and are fastened on external rim 1a of web 1 at at least one of those ends and preferably at straight end 2a, as illustrated by FIGS. 1A and 1B.

[0067] For this purpose, blades 2 are equipped with at least one pair of aligned bores 21 that coincide with corresponding bores configured on rim 1a of web 1 in order to receive appropriate sets of rivets.

[0068] Blades 2 are equipped with at least one pair of aligned orifices 25 creating a space for reception of the rivets for fastening lining G2.

[0069] In the embodiment of FIG. 2B, beveled end 2b terminates in a spatula 24 that is left free in order to cover external rim 1a of web 1.

[0070] Blades 2 are mounted on external rim 1a of web 1 in such a way that the internal edge of beveled end 2b of each blade is arranged parallel with the edge of straight end 2a of the immediately contiguous blade, and so that external edge 2c of the rectangular portion of the blades adjoins the periphery of the web, as illustrated in FIG. 1C.

[0071] Planar end 2a, having a straight edge, of blades 2, which here is riveted to web 1, is adjacent to one of the two pleats 20a, 20b.

[0072] According to a first aspect of the invention, the two pleats 20a, 20b form arches that are identical in width, height, and therefore stiffness, which extend in directions that are both parallel to one another and orthoradial with respect to central rotation axis X of web 1 and thus of the friction disk.

[0073] The “orthoradial” direction can be defined as being orthogonal to rotation axis X and, in particular, perpendicular to the installation radius of blades 2 on web 1.

[0074] The pleats are constituted by three segments 201, 202, 203 inclined at an angle α of between 1° and 20° with respect to the perpendicular plane of central rotation axis X of the friction disk, as illustrated in FIG. 2B.

[0075] The inclination of these segments ensures an elevation h of between 0.5 and 1.5 mm of support region 20 with respect to plane P of web 1.

[0076] This inclination results from a curvature of radius r, as illustrated by FIG. 2B and FIG. 7B.

[0077] After riveting of blades 2, these pleats are moreover positioned symmetrically on either side of the diametrical axis of web 1.

[0078] The supporting means of first lining G1 thus have a uniform stiffness over all blades 2, so as to deform isostatically and elastically.

[0079] More specifically, upon compression of blades 2, their displacement is limited to the orthoradial direction and some of their degrees of mobility are blocked, but each degree of freedom is blocked only once, so that no stress is exerted on the blades.

[0080] The geometry and the profile of the pleats are defined so that the mechanical stresses generated in the blades remain in the elastic range of their constituent material.

[0081] As a consequence, during the re-engagement phase when at least one of linings G1, G2 is subjected to abutment stresses, said stresses are transmitted to support region 20 and to pleats 20a, 20b, which then deform in controlled fashion.

[0082] More specifically, the two pleats compress in the same direction, identically and simultaneously over all the blades, in the manner of hinges, causing a tangential angular offset of the two linings whose friction faces nevertheless remain in parallel planes, as illustrated in FIGS. 3A and 3B, and 6A and 6B.

[0083] The pleats thus compress isostatically.

[0084] This selective deformation of pleats 20a, 20b of support region 20 allows first lining G1 to pivot freely around rotation axis X of the friction disk relative to second lining G2, with no loading or deformation of the friction faces.

[0085] Linings G1, G2 thus remain in a plane perpendicular to axis X.

[0086] According to a variant of the invention (illustrated in particular in FIGS. 7A and 7B), support region 20 comprises a shallow recess 20d, extending radially, halfway between the two pleats 20a, 20b and parallel to them.

[0087] This recess preferably extends radially from one edge of the blade to the other.

[0088] In the embodiments depicted in the Figures, blades 2 have a third pleat 20c, parallel to the other two pleats 20a, 20b and of the same width and height, that is located on beveled end 20b opposite the planar, straight edge 2a riveted to web 1.

[0089] This third pleat 20c is on the one hand separated from the other two pleats by a planar region 23 perforated by at least one, and in this case two, complementary bores 25 for fastening to web 1, and on the other hand is extended by spatula 24.

[0090] Spatula 24 rises to a height that is equal to height h of support region 20 and is thus preferably between 0.5 and 1.5 mm above the plane of web 1.

[0091] In the variant illustrated in FIGS. 1A and 4A, external rim 1a of web 1 has indentations 100 configured in the angular sectors located below pleats 20a, 20b of blades 2.

[0092] Indentations 100 make it possible both to reduce inertia and to configure an axial receptacle for the rivets for fastening first lining G1.

[0093] Web 1 and blades 2 are made of steel sheet, and pleats 20a, 20b, 20c are perpendicular to the rolling direction of the sheet, which allows the risk of dimensional deviations to be reduced.

[0094] In order to control the deformation of support region 20 during the re-engagement phase and to avoid the “cupping” effect (visible in FIG. 3B) which is prejudicial to comfort during the re-engagement phase, in a second aspect the invention makes provision to equip support region 20 with an additional stiffness element.

[0095] This additional stiffness element comprises at least one tab 200 that projects below the planar support region 20.

[0096] One of the ends of this tab is intended to come to a stop against web 1 upon deformation of pleats 20a, 20b, limiting the collapse of region 20, as illustrated in FIG. 6B.

[0097] In the variants illustrated in FIGS. 4A, 4B, 5A, 5B, and 6A, 6B, this stiffness element has in particular two facing tabs 200a, 200b that are delimited by a cutout configured through support region 20.

[0098] There is a single cutout here, in the shape of an H.

[0099] Preferably the two tabs 200a, 200b are identical and extend symmetrically with respect to the central axis of support region 20.

[0100] If support region 20 is also provided with a recess 20d as illustrated in FIG. 7A, that recess is interrupted by the H-shaped cutout and is then in two parts located respectively on either side of tabs 200a, 200b.

[0101] According to another variant that is not depicted, the support region is provided with two longitudinal slots that border and enclose a single, cradle-shaped tab.

[0102] Preferably these slots are parallel and extend tangentially to web 1.

[0103] According to another variant that is also not depicted, the tab is constituted by a boss that is produced, for example, by stamping and extends orthoradially to central axis X of web 1.

[0104] As illustrated in FIG. 7B, tabs 200a, 200b extend at rest with an inclination β of between 1° and 20° with respect to the plane of support region 20 or plane P of web 1, and are located between the two pleats 20a, 20b.

[0105] The four orifices 22 intended to receive rivets R for fastening the first lining are positioned here on either side of the H-shaped cutout.

[0106] As illustrated schematically in FIG. 6B, the arching height of tabs 200a, 200b is substantially equal to half the arching height of support region 20.

[0107] The variant depicted in FIG. 8 of the progressivity device according to the invention corresponds to a one-piece assemblage of web 1 and blades 2.

[0108] Here blades 2 are shaped directly into external rim 1a of web 1 and are separated from one another by L-shaped slots F opening toward the edge of the web.

[0109] In this variant, the pleats do not necessarily all extend in the orthoradial direction.

[0110] As previously, region 20 intended for supporting the linings has an additional stiffness element in the form of tabs 200a, 200b.

[0111] The graph of FIG. 9 presents two curves illustrating the mechanical behavior of a clutch comprising the blades of the progressivity device according to the invention, respectively according to the variant having no additional stiffness element (curve 1) and the variant having said stiffness element (curve 2).