FR2827653A1 - Automobile flexible clutch flywheel comprises annular mass with which laminated annular damping plate, fixed at its outer periphery, rotates, damping plate is fixed at inner periphery to rotate with input shaft - Google Patents

Abstract

The flexible flywheel (10) for a clutch comprises an annular mass (1). A laminated annular damping plate (2) is fixed by bolts (15) at its outer radial periphery to rotate with the annular mass. The damping plate is fixed by bolts (25) at its inner radial periphery to rotate with an input shaft (5).

Description

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 The invention relates to a flexible flywheel for a clutch, in particular for a motor vehicle.

 The invention relates more particularly to a flexible clutch flywheel, of the type comprising an annular mass, an annular damping plate made integral in rotation and axially, on the one hand, at its radially external periphery, with the annular mass by first fixing means and, on the other hand, at its radially internal periphery, of a shaft leading by second fixing means.

 Such a flexible clutch flywheel is for example known from European patent application EP-A-0. 990,817. and illustrated in Figure 1 of this application.

 This document describes more particularly, a flexible flywheel (10) in which an annular mass (1) forming a flywheel is mounted by means of a flexible annular plate (2), here a flexible sheet, at the end of 'a driving shaft (5) such as the crankshaft of an internal combustion engine.

An annular reinforcement (26) is attached to the radially inner part of the flexible annular sheet (2) and holes (225,525) formed respectively in this part and in the annular reinforcement (26) receive axial fixing screws (25) of the flexible flywheel (10) on the driving shaft (5).

 An elastic washer (80), such as a Belleville washer, is interposed between a central part of the flexible sheet (2) and the radially internal part of the annular mass (1) to absorb the bending vibrations transmitted by the shaft. leading (5) and to dampen them by friction on the flexible sheet (2) and on the annular mass (1).

 The flexible sheet (2) is made integral in rotation and axially with the annular mass (1) by axial fixing screws (15). The flexible sheet (2) has, at its radially outer periphery, an axial orientation portion on which a drive ring (30) for the starter is attached by welding.

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 Such a flexible annular plate (2) is relatively expensive to produce, in particular due to the various production operations required. Thus, from a sheet of thick sheet metal, the flexible annular plate (2) is produced successively by a cutting operation which is followed by a heat treatment operation comprising inter alia a quenching and tempering operation, and finally an operation hot leveling to compensate for flatness defects resulting in particular from the treatment operation.

 In addition, such flexible sheets generally have a thickness of the order of 2 to 5 mm so that it is not possible to carry out the processing operation before the cutting operation, that is to say perform the cutting operation on a pretreated sheet.

 The present invention aims in particular to provide a simple, effective and economical solution to these problems.

 To this end, the invention provides a flexible flywheel of the type described above, characterized in that the annular plate is a laminated structure.

 Advantageously, a flexible annular plate according to the invention has a laminated structure which can be produced in a fewer number of operations so that the flexible flywheel thus obtained is less expensive. Indeed, the laminated structure comprises at least two sheets of lesser thickness which it is possible to produce by cutting directly from a pretreated sheet, before stacking them to constitute the laminated structure.

 Preferably, the laminated structure of the annular plate comprises three sheets made of pretreated sheet, for example having a thickness of the order of 0.8 mm, which are cut and stacked for assembly and formation of a unitary sub-assembly.

 Advantageously, the sheets include friction means which intervene due to relative displacements between the two sheets during deformations of the annular plate in operation and constituted by the sheets themselves, so that the friction washer of the type of that provided in document EP-A-0. 990.817 can be deleted.

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 According to other characteristics of the invention: - the laminated structure comprises at least two sheets between which there are friction means which occur due to relative displacements between the two sheets during deformations of the annular plate in operation; the friction means are constituted by at least one prominent part produced in at least one of the sheets, in particular by stamping, and the top part of which is capable of coming into contact with a portion facing the adjacent lateral face of the leaf ; - At least one of the side faces of one of the sheets of the annular plate has a surface condition or a coating to obtain a determined coefficient of friction.

 - At least one friction ring is interposed axially between two sheets of the annular plate; - The laminated structure comprises, at its internal radial periphery, reinforcing means, such as in particular reinforcing washers, arranged axially on either side of the laminated structure; - The laminated structure and the reinforcing washers are made integral by assembly means to constitute a unitary sub-assembly; - The assembly means consist of a weld made in at least one axial groove that comprise the reinforcing sheets and washers at their internal radial periphery; - Means are provided for centering the laminated structure with respect to the driving shaft; - The centering means are constituted by a radially internal extension of at least one of the sheets and 1 or reinforcing washers; - At least one annular spacer is interposed axially between on the one hand one of the sheets and on the other hand, the second fixing means and / or the driving shaft; - The second means of fixing the annular plate to the driving shaft consist of axial screws, and in that a flat ring made of a material with a hardness close to that of the screw head, is interposed axially

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 between the latter and the adjacent annular side face of the sheet or of the reinforcing washer; - At least one of the sheets has at its external radial periphery first means capable of rendering the annular plate and the mass integral in rotation by cooperation of shapes with second complementary means that the mass comprises; - The first means constitute means for centering the annular plate on the annular mass; - At least one of the sheets comprises axial retaining means, such as retaining claws, of the annular plate on the annular mass; - The sheets, at their external radial periphery, are axially delimited by on the one hand the annular mass and, on the other hand, a flat crown secured to the annular mass.

- la figure 3 est une demi-vue en coupe axiale, se ! on) a) igne i))-tti de la figure
4, du volant flexible selon le premier mode de réalisation de l'invention, dans lequel la plaque annulaire présente une structure feuilletée ; - la figure 4 est une demi-vue en coupe transversale du volant flexible selon la figure 3 ; - la figure 5 est une vue en coupe axiale, selon la ligne IV-IV de la figure 3, d'un volant flexible selon les figures 3 et 4 ; - la figure 6 est une vue partielle, en coupe axiale, qui illustre une variante de réalisation selon la figure 4 et dans laquelle les moyens d'assemblage de la Other characteristics and advantages of the invention will appear on reading the detailed description which follows for the understanding of which reference will be made to the appended drawings in which: - Figure 1 is a half-view in axial section of a flexible flywheel according to the prior art, in which the annular mass is mounted by means of a thick flexible sheet on the driving shaft; - Figure 2 is a half view in axial section of a clutch mechanism of axis of rotation XX and which comprises a flexible flywheel according to a first embodiment of the invention;

- Figure 3 is a half view in axial section, se! on) a) igne i)) - tti of the figure
4, the flexible flywheel according to the first embodiment of the invention, in which the annular plate has a laminated structure; - Figure 4 is a half cross-sectional view of the flexible flywheel according to Figure 3; - Figure 5 is an axial sectional view, along the line IV-IV of Figure 3, of a flexible flywheel according to Figures 3 and 4; - Figure 6 is a partial view, in axial section, which illustrates an alternative embodiment according to Figure 4 and in which the assembly means of the

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 plate with laminated structure for forming a sub-assembly consisting of screws; Figure 7 is a partial view, in axial section, which illustrates an alternative embodiment according to Figure 4 and in which the elements forming the sub-assembly are stepped, at their internal radial periphery, so as to constitute a chamfer to facilitate the mounting on the driving shaft; Figure 8 is a view similar to that of Figure 3 which illustrates a first alternative embodiment of the fixing means, said second means, of the annular plate on the drive shaft; Figure 9 is a view similar to that of Figure 6 which illustrates a second alternative embodiment according to Figure 8; FIG. 10A is a view similar to that of FIG. 3 of a flexible flywheel according to a second embodiment of the invention, in which the laminated annular plate is made integral with the annular mass on the one hand, in rotation by a force fitting connection and on the other hand, axially by retaining tabs, better visible on the enlargement of FIG. 10B; Figure 11 is a view similar to Figure 10A of a flexible flywheel which illustrates an alternative embodiment of the reinforcing means of the annular plate; Figure 12 is a view similar to that of Figure 10A, which illustrates an alternative embodiment in which the axial retaining means consist of a flat ring integral with the annular mass; FIG. 13 is a half-view similar to that of FIG. 3 of a flexible flywheel according to a third embodiment of the invention, in which the annular plate comprises friction means constituted by stampings produced on at least one leaves ; Figure 14 is a view similar to that of Figure 13 which illustrates an alternative embodiment of the stampings forming friction means; Figure 15 is a view similar to that of Figure 9, which illustrates an alternative embodiment of the friction means constituted by rings

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 friction interposed, in the medial radial zone, between the lateral faces opposite the sheets of the annular plate; - Figure 16 is a half view in axial section of a flexible flywheel according to a fourth embodiment of the invention, in which the annular plate has two sheets and friction means of the type of those illustrated in Figure 15 .

FIG. 1 is a half-view in axial section of a flexible flywheel of axis of rotation XX according to the prior art, described in the preamble to this description and in which the annular mass is mounted by means of a thick flexible sheet on the drive shaft
In the description which follows, to facilitate understanding, the expressions radial, axial, front, rear, left, right, etc. are used without limitation. with reference to the figures and according to the definitions given in the description.

 In the description, identical, similar or analogous elements will be designated by the same reference numbers.

 FIG. 2 represents an X-X rotation axis clutch mechanism comprising a flexible flywheel according to the invention. Such a mechanism is well known in the art and will only be described here for the record.

 Such a clutch mechanism (100) comprises a diaphragm (110) which is part of a mechanism for clamping a friction disc (120) on an annular mass (1), called the reaction plate, driven in rotation by a driving shaft (5), here the driving shaft.

 The diaphragm (110) is an annular part, the radially outer part of which is in the shape of a Belleville washer (111) constitutes engagement means making it possible to exert an axial thrust on a pressure plate (160) for tightening the friction disc (120 ) on the reaction plate (1), and the radially inner part of which is split radially to form radial fingers (112) constituting declutching means on which a clutch release bearing (130) acts.

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 The diaphragm (110) is supported and guided by a clutch cover (140) fixed on the reaction plate (1) and it is capable of passing from a disengaged position to a clutch position, and vice versa, by tilting on primary and secondary supports which are for example formed by a stamped bottom of the cover (140) or by an annular ring carried by the bottom of the cover as regards the primary support, and by a ring-crown carried by lugs from the bottom of the cover and passing through holes in the diaphragm (110), as regards the secondary support. Alternatively, this secondary support can be formed by baluster heads which extend through orifices in the diaphragm (110) and which are fixed to the cover (140) by crimping.

 The clutch (100) shown in FIG. 2 thus more particularly comprises a cover (140) fixed by screws (145) to an annular mass (1) forming a reaction plate, an annular damping plate (2) made integral in rotation and axially, on the one hand at its radially external periphery, of the annular mass (1) by first fixing means (15) and, on the other hand at its radially internal periphery, of the driving shaft (5) by second fixing means (25).

 The first and second fixing means (15,25) are here constituted by screws.

 A pressure plate (160) is mounted axially displaceable and integral in rotation with respect to the cover (140) by any suitable means known to those skilled in the art, such as tangential tongues.

 The friction disc (120) is intended to be clamped between on the one hand, the pressure plate (160) and, on the other hand, the annular mass (1) forming the reaction plate and it carries two friction linings ( 122) for driving a driven shaft in rotation, in this case the gearbox shaft, the disc (120) of which is rigidly fixed in rotation, alternatively elastically.

 The pressure plate (160) is biased towards its clutch position by the diaphragm (110), coaxial with the drive and driven shafts, on the radial fingers (112) from which the clutch release bearing (130) acts.

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 Thus when the clutch release bearing (130) does not act on the diaphragm (110), the radially external part (111) of the diaphragm (110) is applied to the primary support formed on the bottom of the cover (140) and pushes on the pressure plate (160) in the direction of the annular mass (1), which causes the friction linings (122) to be tightened between the pressure plate (160) and the annular mass (1) so as to establish the transmission of a torque between the driving shaft (5) formed by the motor shaft and the driven shaft formed by the gearbox shaft.

 Conversely, when the stop (130) acts on the radial fingers (112) of the diaphragm (110), the diaphragm swivels by pivoting on the secondary supports and its external part (111) moves away from the pressure plate (160) and is approaches the bottom of the cover (140) in a disengaged position.

 Of course, the clutch may include more than one pressure plate and be advantageously equipped with a wear take-up device, in particular to compensate for the wear of the linings (122) of the friction disc (120).

 As a variant, the reaction plate belongs to a double torsion damping flywheel. According to this variant, the reaction plate is formed by a second mass and rotatably mounted on a first mass formed by an annular mass (1) made integral by means of an annular plate (2) according to the invention, the drive shaft (5). The first mass (1) is therefore connected to the second mass forming the reaction plate against which one of the friction linings (122) of the disc (120) is clamped, the first and second masses being connected by elastic members of radial or circumferential orientation for vibration damping.

 Advantageously, the clutch mechanism, of the type shown in FIG. 2 or of the double damping flywheel type, constitutes a module forming a unitary assembly, so as to be mounted and fixed on the annular plate (2) in a single operation by second fixing means (25), such as screws, the annular plate (2) having been previously mounted and fixed to the driving shaft (5) by the first fixing means (15).

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 Figure 3 is a half view in axial section, along the line lil-lil of Figure 4, the flexible flywheel according to the first embodiment of the invention.

défini par le volant flexible (10), ainsi la désignation avant sera utilisée pour les éléments situés à gauche de ce plan selon la figure 3, c'est à dire du côté de l'arbre moteur et inversement la désignation arrière sera utilisée pour les éléments situés à droite de ce plan toujours selon la figure 3, c'est à dire du côté de l'arbre de boîte de vitesses. In the following description, the front and rear designations will be used and considered in relation to a median plane of radial orientation

defined by the flexible flywheel (10), so the front designation will be used for the elements on the left of this plane according to Figure 3, i.e. on the side of the motor shaft and conversely the rear designation will be used for elements located to the right of this plane still according to Figure 3, that is to say on the side of the gearbox shaft.

 Thus, FIG. 3 represents a flexible flywheel (10) comprising an annular mass (1) forming the reaction plate of the clutch mechanism (not shown), an annular damping plate (2) according to the invention, characterized by the fact that the annular plate (2) is a laminated structure.

 The laminated structure of the annular plate (2) comprises in this first embodiment three sheets, a first central sheet (2a) and, on either side, respectively at the front and at the rear, two other sheets (2b, 2c).

 The annular plate (2) is made integral in rotation and axially, on the one hand at its radially external periphery, with the annular mass (1) by first fixing means (15) and, on the other hand, at its periphery radially internal, of a driving shaft (5) by second fixing means (25).

 The first fixing means (15) here consist of axial screws (15) which successively comprise from front to back, a head (16) capable of cooperating with a mounting tool, an annular flange (17) of larger diameter as the head (16) which bears on the adjacent face opposite, such as the front face (20b) of the sheet (2b).

 The screws (15) pass through first through holes (215) that the annular plate (2) comprises, the screws (15) comprising, after the head (16) and the annular part (17), a barrel in a section before which an annular groove (18) is produced and the rear section of which comprises a threaded portion (19).

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 The annular groove (18), when the annular plate (2) is fixed to the mass (1), is substantially axially aligned with the sheets of the annular plate (2) at the holes (215), made in the sheets for the passage of part of the screws (15) and so that a radial clearance exists between the edges of the sheets delimiting the holes (215) and the bottom of the annular groove (18).

 The screws (15) penetrate into tapped holes (315) of the annular mass (1) in order to make the annular plate (2) of the annular mass (1) integral in rotation and axially by screwing.

 In axial section, the half annular mass (1) here has substantially an L-shape comprising a first branch of radial orientation and a second branch of axial orientation.

 The radial orientation branch has a front face (13) on which the annular plate (2) is partially supported after mounting, and a rear face (11) which cooperates with one of the friction linings (122) of the disc (120) when the clutch is in the engaged position.

 Advantageously, the annular plate (2) with laminated structure is more flexible than a plate made up of a single sheet of the same thickness, so that for an identical stiffness the annular plate (2) laminated can be produced on a smaller external diameter. .

 Thus, one can take advantage of the radially peripheral zone of the annular mass (1) to produce, beyond the screws (15), a crown (12) which projects axially beyond the face (13) of the mass annular (1) and advantageously makes it possible to increase the mass at the external radial periphery of the annular mass (1), and therefore to increase its inertia.

 A drive ring (30) for the starter is here attached to the annular mass (1) radially outside the ring (12) on its radially external surface, or as a variant is produced in the annular mass (1) .

 The annular mass also includes an ignition target produced axially behind the crown (30).

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 According to this first embodiment, the annular plate (2) is a laminated structure constituted here by three sheets (2a, 2b, 2c), for example each having a thickness of between 0.4 mm and 1.5 mm.

 Of course, the number of sheets, which is at least equal to two, constituting the annular plate (2) can vary according to the applications and the desired performances.

 The sheets (2a, 2b, 2c) are advantageously cut from strips, for example from sheet metal, previously treated so that such an annular damping plate (2) with a laminated structure is less costly to produce, and this in particular thanks to removing the planing operation and carrying out the processing operation on the sheet metal strips and not piece by piece after the cutting operation.

 The sheets (2a, 2b, 2c) of the plate (2) comprise, at their radially external periphery, a first series of through holes (215) through which the first fixing means (15) pass and at their radially internal periphery, a second series of through holes (225) crossed by the second fixing means (25), respectively.

 The screws constituting the second fixing means (25) by which the sheets (2a, 2b, 2c) of the annular plate (2) are made to rotate and axially integral with the driving shaft (5) are screwed into tapped holes (525) that includes the driving shaft.

 The plate (2) with a laminated structure here comprises, at its internal radial periphery, reinforcement means (8) constituted for example by front (8b) and rear (8c) reinforcement washers, which are arranged axially on either side other of the laminated structure.

 These washers (8b, 8c) constitute reinforcing means (8) of the annular plate (2) in the zone where the stresses are the highest, that is to say in the vicinity of the driving shaft (5).

 An annular spacer (26) is interposed axially between the reinforcing washer (8c) and each screw head (25), this spacer (26) is preferably made of a material with a hardness close to that of the screw in order to '' avoid matting problems during tightening.

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 Advantageously, means are provided for centering the annular plate (2) relative to the driving shaft (5).

 The plate (2) and the reinforcing washers (8) are preferably made integral by assembly means to constitute a unitary sub-assembly.

 The unitary sub-assembly comprises centering means which here consist of a radially internal extension (29) of at least one of the sheets (2a, 2b, 2c) of the plate, as a variant by one of the washers reinforcement (8b, 8c), the extension (29) defining a central hole which is centered on a cylindrical bearing surface (529) of the driving shaft (5).

 FIG. 4 is a half-view in cross section of the flexible flywheel according to FIG. 3 and FIG. 5 is a view in axial section, along the line IV-IV of FIG. 3, of a flexible flywheel according to FIGS. 3 and 4.

 Figures 4 and 5 illustrate a particular embodiment of assembly means for constituting such a sub-assembly, in which the assembly means consist of a weld (27) produced in at least one axial groove (28) which comprise , at their internal radial periphery, the sheets (2a, 2b, 2c), the reinforcing washers (8b, 8c) and possibly the spacer (26).

 FIG. 6 is a partial view, in axial section, which illustrates an alternative embodiment according to FIG. 4 or 5 and in which the means for assembling the sheet with a laminated structure for forming a sub-assembly are constituted by screw (125).

 Thanks to the screws (125), it is possible to constitute a sub-assembly of the various elements through which the screws (125) pass, by virtue of the sandwich mounting, a separate and integral sub-assembly is thus obtained, and therefore easily transportable and manipulable.

 The spacer (26) is here split into a first spacer (26b) and a second spacer (26c) as will be explained more precisely in FIG. 9.

 Of course as a variant, any other linking principle can be used to constitute such a sub-assembly comprising the sheets (2a, 2b, 2c) and at

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 minus the reinforcing washers (8b, 8c), so the sub-assembly could be obtained for example by gluing, stapling or even by riveting.

 Figure 7 is a partial view, in axial section, which illustrates an alternative embodiment according to Figure 4 and in which the elements forming the subassembly are stepped, at their inner radial periphery, so as to constitute a chamfer (55) to facilitate mounting the sub-assembly on the drive shaft (5).

 The chamfer (55) is obtained by staggering the internal diameters of the elements of the sub-assembly, i.e. sheets (2a, 2b, 2c) and reinforcing washers (8b, 8c), thus the reinforcing washer ( 8b) which is axially furthest forward is of an internal diameter smaller than that of the sheet (2b) arranged axially behind and so on.

 Figure 8 is a view similar to that of Figure 3 which illustrates a first alternative embodiment of the fixing means, said second means (25), of the annular plate (2) on the drive shaft (5).

 According to this variant, the annular spacer (26) can here be made of a material of low hardness and produced without heat treatment.

 Indeed, a flat ring (40) made of a material with a hardness close to that of the screw head, is interposed axially between the screw head and the adjacent side face, here of the spacer (26), in variant of one of the sheets of the plate (2a, 2b, 2c) or of one of the reinforcing washers (8b, 8c) when the spacer (26) is interposed axially between the annular plate (2) and the leading tree (5).

 FIG. 9 is a partial view, in axial section, which illustrates a second embodiment according to FIG. 8.

 According to the second variant of Figure 9, the spacer (26) is here advantageously split into a first spacer (26b) interposed between the drive shaft (5) and the adjacent side face of the reinforcing washer (8b) and in a second spacer (26c) which is interposed between the adjacent face the reinforcing washer (8c) and the flat ring (40).

 Of course, depending on the hardness of the material of the spacer (26c) relative to the screw (25), the flat ring (40) can be removed as in FIG. 3.

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 Thanks to the doubling of the spacer (26), the position of the assembly constituted by the annular plate (2) and the annular mass (1) can be adjusted axially with respect to the driving shaft (5). Thus, it is possible to position more precisely the annular mass (1) and therefore the drive ring (30) of the starter and the ignition target relative to the sensor located opposite, which are integral with the annular mass (1).

 FIG. 10A is a view similar to that of FIG. 3 of a flexible flywheel (10) according to a second embodiment of the invention, in which the laminated annular plate (2) is made integral with the annular mass (1 ) on the one hand, in rotation by a force fitting type connection and on the other hand, axially by claws or retaining lugs (63).

 According to FIG. 10A, at least one of the sheets, here the central sheet (2a), comprises at its external radial periphery first means, such as teeth (62), capable of rendering the annular plate (2) and the mass ( 1) integral in rotation after press fitting, by cooperation of shapes of the teeth (62) with second complementary means (61) that comprises the mass (1), as is better visible on the enlargement of FIG. 10B.

 Thus, the annular plate (2) having three sheets (2a, 2b, 2c), at least one of the sheets, here the sheet (2a), ensures the connection in rotation by cooperation of shapes with the annular mass (1) for example by cooperation of teeth forming the first and second means (62,61). The sheet (2b) has retaining claws (63) which extend forward and cooperate with the cylindrical surface opposite the annular mass (1) to ensure by arcboutement the axial maintenance of the laminated structure against the face (13) of the mass (1).

 The first means (62), that is to say here the toothing formed at the outer radial periphery of the central sheet (2a), constitute means for centering the annular plate (2) on the annular mass (1), advantageously the central sheet (2a) also has at its internal radial periphery an extension (29) for centering the plate (2) on the driving shaft (5).

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 Figure 11 is a view similar to Figure 7 of a flexible flywheel which illustrates an alternative embodiment of the reinforcing means (8) of the annular plate (2).

 According to this alternative embodiment, the reinforcing means (8) are produced in the form of two reinforcing washers (8b, 8c) as described above.

 Thanks to the fact that at least one of the washers (8b, 8c) has at its external radial periphery, a rounded portion (82), oriented respectively forwards for the washer (8b) and rearwards for the washer ( 8c), the sheets (2a, 2b, 2c) are advantageously guided during their bending in operation.

 Preferably, the washers (8b, 8c) are symmetrical so as to be able to standardize the construction, as a variant the outside diameter of the rear washer (8c) is greater than the outside diameter of the front washer (8b) as illustrated in the figure. 11.

 Figure 12 is a view similar to that of Figure 10A, which illustrates an alternative embodiment in which the axial retaining means consist of a flat ring (73) secured to the annular mass (1).

 The axial retaining lugs (63) of FIG. 10A are therefore here replaced by the flat crown (73) so that the sheets (2a, 2b, 2c) of the annular plate (2) are bounded axially, at their radial periphery external, by on the one hand the annular mass (1) and, on the other hand, the flat crown (73).

 The crown (73) is for example fitted tight onto the annular mass (1).

 FIG. 13 is a half-view similar to that of FIG. 3 of a flexible flywheel according to a third embodiment of the invention, in which the annular plate (2) comprises friction means (80) which intervene from the made of relative displacements between the sheets (2a, 2b, 2c) during the deformation of the annular plate (2) in operation.

 Advantageously, the friction means (80) consist of the sheets (2a, 2b, 2c) themselves, which during the elastic deformation of the annular plate (2), rub between them due to relative displacements, in particular

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 in the radially median zone of the sheets (2a, 2b, 2c), so that for certain applications it is thus not necessary to provide additional friction means.

 Preferably and in order to better control the friction occurring between the sheets (2a, 2b, 2c), the friction means (80) consist of at least one protruding part (80a, 80b, 80c) produced in at least one of the sheets (2a, 2b, 2c) and the top part of which is able to come into contact with a portion opposite the adjacent sheet.

 The friction means (80) here consist of stampings (80a, 80b, 80c) made in each of the sheets (2a, 2b, 2c) of the plate (2) and which interpenetrate so that the top part of one come partially into contact with part of the next to control the friction surfaces.

 Figure 14 is a view similar to that of Figure 13 which illustrates an alternative embodiment of the stampings forming friction means (80).

 According to this variant, stampings (90b, 90c) are here produced respectively on the sheets (2b) and (2c) and in opposite directions so that the top parts of the stampings (90b, 90c) are oriented towards the central sheet. (2a) and come into contact respectively with each of its front and rear side faces.

 Of course, the friction means (80) are not necessarily formed by prominent parts (80a, 80b, 80c) produced by stamping, many variants can be envisaged.

 FIG. 15 is a view similar to that of FIG. 9, which illustrates an alternative embodiment of the friction means (80) consist of at least one friction ring (85) interposed, in the median radial zone, between the faces lateral facing at least two sheets of the annular plate (2).

 According to FIG. 15, the annular plate (2) comprises three sheets (2a, 2b, 2c) between the lateral faces opposite which two friction rings (85) are interposed, such as rings made of synthetic material, loaded or no, and advantageously continuous.

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 As a variant and as illustrated in FIG. 15, when the spacer (26) is split into two spacers (26b, 26c), these two spacers can be of different hardness, thus the spacer (26b) is here of a hardness greater than the spacer (26c), the spacer (26c) being associated with a flat ring (40).

 FIG. 16 is a half view in axial section of a flexible flywheel according to a fourth embodiment of the invention, in which the annular plate (2) comprises only two sheets (2b, 2c) between the lateral faces of which friction means (80), here a friction ring (85) of the type of those illustrated in Figure 15, are interposed.

 As already explained above, at least one of the sheets of the annular plate (2) or one of the elements of the sub-assembly comprises centering means (29), here these means are produced by an external radial extension of the reinforcement washer (8b).

 According to a preferred embodiment of the invention, the friction means (80) consist of direct friction occurring between the sheets of the plate (2), without additional friction means, the sheets (2a, 2b, 2c) can then advantageously have undergone surface treatments, especially locally in the central radial zone, so as to modify the coefficient of friction and / or the resistance to wear.

 As a variant, the sheets (2a, 2b, 2c) of the annular plate (2) have, on at least one of their lateral faces, a coating in order to increase the coefficient of friction and 1 or absorb the energy.

 Of course, the different variant embodiments can apply equally to the different embodiments described here by way of example.

Claims (16)

CLAIMS 1. Flexible flywheel (10) for a clutch, in particular for a motor vehicle, of the type comprising an annular mass (1), an annular damping plate (2) made integral in rotation and axially, on the one hand, at its radially external periphery of the annular mass (1) by first fixing means (15) and, on the other hand, at its radially internal periphery, of a driving shaft (5) by second fixing means (25) , characterized in that the annular plate (2) is a laminated structure. 2. flexible flywheel (10) according to claim 1, characterized in that the laminated structure comprises at least two sheets between which are provided friction means (80) which occur due to relative displacements between the two sheets during deformations of the annular plate in operation. 3. flexible flywheel (10) according to claim 2, characterized in that the friction means (80) consist of at least one protruding part made in at least one of the sheets, in particular by stamping, and the top part of which is suitable coming into contact with a portion opposite the adjacent side face of the sheet. 4. flexible steering wheel (10) according to claim 2 or 3, characterized in that at least one of the lateral faces of one of the sheets (2a, 2b, 2c) of the annular plate (2) has a surface condition or a coating to obtain a determined coefficient of friction. 5. Flexible flywheel (10) according to claim 2 or 3, characterized in that at least one friction ring (85) is interposed axially between two sheets (2a, 2b, 2c) of the annular plate (2). <Desc / Clms Page number 19> 6. flexible flywheel (10) according to any one of the preceding claims, characterized in that the laminated structure comprises, at its internal radial periphery, reinforcing means, such as in particular reinforcing washers (8), arranged axially of on either side of the laminated structure. 7. Flexible steering wheel (10) according to any one of the preceding claims, characterized in that the laminated structure and the reinforcing washers (8) are made integral by assembly means (27,125) to constitute a unitary sub-assembly . 8. flexible flywheel (10) according to claim 7, characterized in that the assembly means consist of a weld (27) made in at least one axial groove (28) that comprise the reinforcing sheets and washers (8) to their internal radial periphery. 9. flexible steering wheel (10) according to any one of the preceding claims, characterized in that there are provided centering means (29) of the laminated structure with respect to the driving shaft (5). 10. Flexible flywheel (10) according to claim 9, characterized in that the centering means consist of a radially internal extension (29) of at least one of the sheets and 1 or reinforcing washers (8). 11. Flexible steering wheel (10) according to any one of the preceding claims, characterized in that at least one annular spacer (26) is interposed axially between on the one hand one of the sheets and on the other hand, the second fixing means (25) and! or the leading tree (5). 12. flexible flywheel (10) according to any one of the preceding claims, characterized in that the second fixing means (25) of the annular plate (2) on the driving shaft (5) consist of axial screws, and in this <Desc / Clms Page number 20>  that a flat ring (40) made of a material with a hardness close to that of the screw head, is interposed axially between the latter and the adjacent annular lateral face of the sheet or of the reinforcing washer (8). 13. Flexible flywheel (10) according to any one of the preceding claims, characterized in that at least one of the sheets has at its external radial periphery first means (62) capable of rendering the annular plate (2) and the mass (1) integral in rotation by cooperation of shapes with second complementary means (61) that comprises the mass (1). 14. Flexible steering wheel (10) according to claim 13, characterized in that the first means (62) constitute means for centering the annular plate (2) on the annular mass (1). 15. Flexible steering wheel (10) according to any one of the preceding claims, characterized in that at least one of the sheets has axial retaining means, such as retaining claws (63), of the annular plate (2) on the annular mass (1). 16. Flexible steering wheel (10) according to any one of the preceding claims, characterized in that the sheets, at their external radial periphery, are delimited axially by the annular mass on the one hand and, on the other hand, a flat crown (73) secured to the annular mass (2).