FR2609132A1 - Damping flywheel for transmission, particularly for a motor vehicle - Google Patents

Abstract

The invention relates to a damping flywheel, between the parts A, B of which there act, radially, rolling means 21 and, axially, a stack 35 of washers. According to the invention, and in combination, on the one hand the washers of the stack 35 are subjected to the elastic means for loading the rolling means 21 and, on the other hand, one 52 of these washers is rotationally keyed onto either one of the coaxial parts A, B in question whilst between another of them, 53, and the other of the said coaxial parts A, B, there act means for engagement with play. Application, particularly, to damping flywheels for motor vehicle transmission.

Description

"Damper flywheel for transmission,
especially for motor vehicles "
The present invention relates generally to flywheels for transmission, of the type of those usually constituting a part of inertia in clutches, in particular in clutches intended for the equipment of motor vehicles.

It relates more particularly to those of these flywheels, or damping flywheels, within which damping means are incorporated with regard to possible torques
As we know, in fact, to filter the vibrations likely to arise throughout the kinematic chain that constitutes a transmission, kinematic chain which, on a motor vehicle, goes from the engine to the wheel shafts, it is usual to insert, in such a transmission, a torsion damping device.

 Most often, this torsion damping device is incorporated into the clutch friction disc.

 However, as a variant, or in addition, it has already been proposed, for certain particular applications, in particular for vehicles whose engine develops a relatively significant torque at low revs for which minimization of the noises commonly known as "trash" noises. ", that is to say noises appearing under torque, must be more particularly sought after, to incorporate such a torsion damping device into the steering wheel.

 Overall, a flywheel, or damping flywheel, into which a torsion damping device is thus incorporated, comprises two coaxial parts, which, each forming for their part, a mass of inertia, are mounted to rotate relative to the 'other, with intervention, between them, circumferentially, for at least a portion of their angular movement, of elastic means with circumferential action, and, axially, for the desired damping, of at least one friction washer.

 In practice, this friction washer is itself subjected to elastic means with axial action, and, these being most often constituted by an elastic washer, there is thus, axially, within such a damping flywheel , a stack of washers, at least one of which is a friction washer, and another of which is an elastic washer.

 This is the case, for example, for the damping flywheel which is the subject of the French patent application filed on March 14, 1986 under No. 86 03664.

 Of course, between the two coaxial parts of such a damping flywheel, there are also, radially, rolling means.

 For reasons explained in detail in the French patent application No. 86 03664 mentioned above, these rolling means are subjected axially to elastic loading means, and, according to the arrangement described in this French patent application, these elastic means load constitute by themselves the elastic means to which is also subjected the friction washer used.

 On this friction washer depends the damping obtained, this damping being like the offset, or "hysteresis", existing, due to the friction, between, on the one hand, the value of the torque transmitted from one of the parts coaxial with the other for an increasing evolution of this couple, and, on the other hand, for the same angular movement between these coaxial parts, the value of this couple for a decreasing evolution of this one.

 Most often, a single friction washer is used, and this intervenes indifferently throughout the angular displacement between the two coaxial parts, even though the conditions according to which the elastic means with circumferential action interposed between those intervene. -these are modulated, they, during this angular displacement, or even that, as is the case in the French patent application No. 86 03664 mentioned above, these elastic means with circumferential action only intervene during of a second portion of this angular movement, the friction washer being the only one to intervene during a first portion of the latter.

 In other words, hysteresis is to date most often the same throughout the angular displacement between the two coaxial parts.

 However, for good filtration of the noises likely to occur, certain operating regimes require a low hysteresis, and others a high hysteresis.

 For example, for good filtration of noises1 commonly known as “neutral noise”, which, due to the gearbox1 are likely to develop with the vehicle stationary, gearbox in neutral, engine idling, there has an interest in having a low hysteresis; on the other hand, when starting and stopping the engine for example, it is advantageous for the hysteresis to be strong.

 By themselves, these two contradictory requirements are difficult to reconcile.

 In addition1 when, as indicated, no elastic means with circumferential action intervene during a first portion of the angular movement between the two coaxial parts, minimizing the hysteresis for this portion of the angular movement leads to a drawback, which is the following.

 Although, for the corresponding operating regime, which is the neutral point regime, there is no torque to transmit from one of the coaxial parts to the other, that of these coaxial parts which is linked to the shaft input of the gearbox is the object on the part of the latter of a drag torque, so that, angularly, its mean position between its successive oscillations moves continuously relative to the coaxial part linked to the motor output shaft, and that, very quickly, at each of these oscillations, there is a shock between it and the elastic means with circumferential action intended to intervene, under torque, between these coaxial parts.

 This results in a neutral noise, which is not due to the gearbox, but which is due to the very constitution of two coaxial parts of the damping flywheel.

 To make this parasitic neutral noise disappear, it suffices to increase the hysteresis.

 However, in practice, this increase is itself liable to cause the neutral noise due to the gearbox to reappear.

 The problem thus to be solved is all the more complex since the hysteresis values to be reconciled are in a ratio of the order of one to three, and that, for reasons of both size and cost, there it is desirable that the number of parts to be used be minimal.

 The present invention generally relates to a provision making it possible to provide a satisfactory solution to this problem.

 More specifically, it relates to a damping flywheel for transmission, in particular for a motor vehicle, of the type comprising two coaxial parts, which, each forming an inertial mass, are mounted to rotate relative to each other, with intervention between them, radially, of rolling means subjected axially to elastic load means, circumferentially, for at least a portion of their angular displacement, of elastic means with circumferential action, and, axially, of a stack of washers of which at least one is a friction washer, this damping flywheel being generally characterized in that, in combination, on the one hand, the washers of said stack are subjected to the elastic means for loading the rolling means, and, on the other hand, one of said washers is locked in rotation on any one of the coaxial parts concerned while between another of them and the other of said coaxial parts there are interlocking means at play.

 Thus, for low values of the angular movement between the two coaxial parts, only that of these washers intervenes which is locked in rotation on one of these coaxial portions, while the other of said washers does not add its effects to the previous one that after an angular movement corresponding to the play of the interlocking means play between it and the other of said coaxial parts.

 For low values of angular displacement, the hysteresis can therefore, as desired, remain low, while the friction due to the second washer intervening in practice before the intervention of the elastic means with circumferential action interposed between the two coaxial parts, the shock, against these1 at each oscillation, of the coaxial part linked to the input shaft of the gearbox, is advantageously braked, and it therefore does not result in the production of any significant noise .

 Jointly, the elastic load means being the same for the rolling means and the washers in question, the overall number of parts to be used is, as also sought, advantageously minimized.

 Finally, these washers being thus disposed in the vicinity of the rolling means interposed between the two coaxial parts, they extend, like these rolling means, along a circumference of relatively reduced diameter, so that the mass of material to which they correspond , and therefore their cost, are themselves advantageously relatively reduced.

 Thus, thanks to the arrangement according to the invention, a particularly advantageous compromise is found between the various requirements to be satisfied.

The characteristics and advantages of the invention will become apparent from the description which follows, by way of example with reference to the appended schematic drawings in which
Figure I is, with local cutouts, a partial elevational view in section of a damping flywheel according to the invention, along the broken line II of Figure 2
Figure 2 is, on a larger scale, a partial view in axial section of this damping flywheel, along the broken line II-II of Figure 1
Figure 3 shows, on an even larger scale, the detail of Figure 2 identified by an insert III in this Figure 2
Figure 4 is a partial elevational view along arrow IV of Figure 3
Figure 5 is a partial view in cross section along the line VV of Figure 3
Figures 6, 7 are views which, respectively analogous to those of Figures 3, 5, correspond to an alternative embodiment
Figure 8 is a partial view in axial section, which, similar to that of Figure 3, relates to another alternative embodiment
Figure 9 is a partial cross-sectional view of this alternative embodiment, along the line IX-IX of Figure 8
Figures 10-11, 12-13 and 14-15, are partial views similar to those of Figures 3-5, and relate to other alternative embodiments
FIG. 16 is a partial view in circumferential section of the embodiment shown in FIGS. 14-15, this circumferential section being taken along the line XVI-XVI of FIG. 14.

 As illustrated in these figures, the damping flywheel according to the invention comprises, overall, two coaxial parts A, B mounted to rotate relative to one another.

 By screws 10, shown diagrammatically in broken lines in FIG. 2, the part A, or input part, is intended to be secured to a shaft 11t in practice a driving shaft, for example the output shaft, or crankshaft, of the engine1 in the case of the equipment of a motor vehicle.

 This part A comprises 1 annularly, around the axis of the assembly, a hub 12, and, integral with this hub 12, on the side of the shaft II, a flange 13.

 In practice, and as shown, the hub 12 is secured to this flange 13 by the preceding screws 10, screws 14 however being provided to ensure its prior attachment to this flange 13 before the intervention of the latter, FIG. 1.

 In practice, also, in the embodiments shown, the part A comprises, parallel to the flange 13, but at a distance therefrom, on the side of the hub 12, a second annular flange 13 '.

 By their external periphery, or of larger diameter, the flanges 13, 13 ′ have substantially the same radial development, and they are secured to one another, for example by rivets 16, as shown, with insertion, between them, an annular spacer 1-7.

 In the embodiments shown, this annular spacer 17 has a toothing 18 at its outer periphery, and it therefore constitutes by itself a starter ring for the assembly.

 Unlike the flange 13, the flange 13 'a1 in the direction of the axis of the assembly, a radial development reduces this flange 13' stopping largely at a distance from the hub 12.

 Part B, or outlet part, also includes a hub 20.

 This hub 20 surrounds the hub 12 of part A, with interposition, radially, of rolling means 21.

 According to the usual methods in the matter, and which will therefore not be described here, these rolling means 21 are constituted by one or two bearings, and, as will be explained later, they are subjected axially to elastic load means .

 The internal ring of the or these bearings is for example forcibly engaged on the hub 12 of the part A1 until it abuts against a transverse shoulder 22 of the latter.

 Jointly, the corresponding outer ring is freely engaged in the hub 20 of part B, until it abuts against a flange 23 which, integral with the hub 20 of part B, extends radially in the direction of the axis of the together.

 The hub 20 of the part B is also integral with a flange 24, which, annularly projecting from the external periphery of this hub 20, extends radially in the direction opposite to the axis of the assembly, parallel to the flange 13 of the part A, in the immediate vicinity of this flange 13, but following a radial extension much less than that of the latter.

 In the embodiments shown, the flange 23 and the flange 24 of the hub 20 are in one piece with the latter, the assembly forming a solid part.

 Part B also includes a flange 26 which, by screws 27, is attached to the hub 20, on the side opposite the flange 24, and which is thus secured in rotation to this hub 20.

 By this flange 26 which, essentially, extends outside the volume defined by the flanges 13, 13 'of part A, the damping flywheel according to the invention is adapted to be able to serve as a reaction plate for a friction disc, not shown, and to be thus secured in rotation, by friction, to this friction disc, even though the hub of the latter is rotationally secured to a second shaft, in practice a driven shaft, for example the input shaft of a gearbox in the case, more particularly concerned, of the equipment of a motor vehicle.

 The flange 26 defines, axially, with the flange 24, an annular volume in which a torque limiter 28 operates.

 In the embodiments shown, this torque limiter 28, which belongs to part B, comprises, parallel to one another, at a distance from each other, two sails 30 with, between these sails 30 , elastic means with axial action which tend to separate them from one another for the clamping of two friction washers 31, one against the flange 24, the other against the flange 26.

 In the embodiments shown, these elastic means with axial action are constituted by two elastic washers 32, 33 of the Belleville washer type, which, with opposite conicities with respect to each other, are radially arranged one in the 'other.

 These provisions are well known in themselves, and not forming part of the present invention, they will not be described in more detail here.

 In a manner also known per se, the coaxial parts A, B thus formed, which each form a mass of inertia, are mounted to rotate relative to one another, with intervention between them, radially, of the rolling means 21 previously mentioned, circumferentially, for at least a portion of their angular displacement, of elastic means with circumferential action, detailed below, and, axially, of a stack 35 of washers, of which at least one, as also detailed ci -after, is a friction washer.

 In the embodiments shown, the elastic circumferential action means intended to intervene between the parts A, B comprise elastic circumferential action members 36, which are five in number in these embodiments, and which are each arranged individually in housings 37 provided for them in the flanges 13, 13 ′ of part A.

 With these elastic circumferential action members 36 are capable of interfering arms 38 belonging to the webs 30 of part B, these arms 38 each extending individually radially between two successive such elastic circumferential action members 36.

 Like the latter, these arms 38 are therefore five in number in the embodiments shown.

 In practice, in these embodiments, the elastic members with circumferential action 36 are springs of the coil spring type, they are elongated substantially tangentially to the same circumference of the assembly, and, at their circumferential ends, they bear. on end caps or cups 40, which are circumferentially interposed between them and the radial edges 41 of the housings 37 in which they are arranged, and which, on the side of said radial edges 41, each individually have, in hollow, a bowl 42 with turned concavity towards such a radial edge 41.

 For the rest configuration of the assembly, FIG. 1, the end pieces 40 are in contact with the radial edges 41 of the housings 37, under the stress of the circumferential action members 36 which extend between them, and possibly these are then prestressed.

 For cooperation, by means of the end pieces 40, with the elastic circumferential members 36, the arms 38 of the webs 30 of part B each have two fingers 44T, 44R which extend circumferentially in opposite directions, one with respect to to the other, the finger 44T extending in the circumferential direction supposed to correspond to an operation of the assembly, known as a "pulling" function, for which an increasing evolution of the torque passing through the damping flywheel develops, while finger 44R extends in the circumferential direction opposite to the previous one, and supposed to correspond to a "retro" operation of said assembly, for which the evolution of said torque is then decreasing.

 In practice, the finger 44T extends in the opposite direction relative to the direction of rotation of the assembly, identified by the arrow F1 in FIG. 1, and the finger 44R extends in the same direction as this direction of rotation.

 For the rest configuration of the assembly, FIG. 1, the fingers 44T, 44R which each of the arms 38 of the webs 30 of part B thus have are both circumferentially spaced from the bottom of the bowl 42 of the end caps 40 of the elastic members with circumferential action 36 between which extends such an arm 38, while possibly being partially engaged in such a bowl 42.

 In other words, for the rest configuration of the assembly, there is, overall, a circumferential clearance between said arms 38 and said end pieces 40.

 Let J be this circumferential clearance.

 it is distributed in JT on the side of the fingers 44T, and JR on the side of the fingers 44R.

 J = JT + JR.

 For example, this circumferential clearance J can be of the order of 20 '.

 According to the invention, and in combination, on the one hand, the washers of the stack 35 are subjected to the elastic load means of the rolling means 21, and, on the other hand, and as detailed below, l 'one of said washers is locked in rotation on any one of the coaxial parts A, B concerned while between another of them and the other of these coaxial parts A, B intervene means of engagement with play.

 In the embodiments shown, the stack 35 of washers detailed below is arranged between the flange 13 of the hub 12 of part A and the hub 20 of part B.

 In practice, this stack 35 extends in line with the flange 24 of the hub 20, thanks to a recess 46 of this hub 20 delimited axially by its flange 23.

In the embodiment more particularly shown in FIGS. 1 to 5, the stack 35 comprises, successively, from the flange 13 of the hub 12 of part A to the flange 23 of the hub 20 of part B, a protective washer 48 , which is in contact with the flange 13, a washer 49, which is an elastic washer with axial action forming the elastic load means of the rolling means 21, and it is in this case a washer
Belleville, a distribution washer 50, which, as described below, is locked in rotation on the flange 13, a friction washer 51, a second distribution washer 52, which itself, as also described below afterwards, is locked in rotation on the hub 20, and, in contact with said hub 20, and, more precisely, with the flange 23 thereof, a washer 53.

 For its setting in rotation on the flange 13 of the hub 12, the distribution washer 50, which, with the protective washer 48, constitutes, for the elastic washer 49, a kind of box, present, at its outer periphery, at least a lug 55, which, directed axially in the direction of said flange 13, is engaged with a plastic pad 56 itself forcibly engaged in a recess 57 provided for this purpose in the flange 13 and split, FIGS. 3 and 4, which makes it possible to catch up with manufacturing tolerances and minimize backlash.

 The friction washer 51 can either be free or linked to any one of the distribution washers 50, 52 between which it intervenes.

 In the embodiment shown, it bears, by its external periphery, on the cylindrical lateral wall of the recess 46 of the hub 20, which, when it is free, is sufficient for its radial retention.

 For its setting in rotation on the hub 20 of part B, the distribution washer 52, which is identical to the distribution washer 50, comprises, like the latter, at its outer periphery, at least one lug 58, but this lug extends axially in the direction of said hub 20, for engagement in a recess 61 provided axially for this purpose therein.

While the distribution washer 52 to which it is attached is thus locked in rotation on the part
B, the washer 53 meshes with play with the hub 12 of part A.

 In the embodiment shown, this hub 12 has, at its outer periphery, for constituting the meshing means with corresponding clearance, a toothing 59 formed of at least two teeth 60 suitably spaced from each other circumferentially, and the washer 53 comprises 1 jointly, at its internal periphery, at least one tab 62, which extends at least radially in the direction of the axis of the assembly, and which is engaged with clearance between the two said teeth 60.

 Let J 'be the overall circumferential clearance of the clearance engagement means thus formed.

 For the rest position of the assembly, FIG. 5, it is distributed like the previous set J, in J'T in the circumferential direction corresponding to an operation in "draft", and in J'R in the circumferential direction, opposite to the previous one, corresponding to a "retro" operation, on either side of the tab 62 of the washer 53 in question.

 Overall, in the embodiment shown, it is between O and the previous set J.

 But it would not go beyond the scope of the invention to give it a higher value.

 As will be noted, the washer 53, which is therefore the one which meshes with play with the hub 12 of the part A, extends, axially, between the hub 20 of the part B and a washer, namely the washer distribution 52, locked in rotation on the hub 20.

 In addition1 on the other side of the washer 52 relative to the washer 53, is disposed1 beyond, in this case, the friction washer 51, a washer, namely the distribution washer 50, which is wedged in rotation on the hub 12 of part A, since, by lugs 55, it is locked in rotation on the flange 13 with which this hub 12 is secured.

 In the embodiment shown, the washers 50, 52 thus wedged each respectively on the parts A and B are separated from each other by the friction washer 51, but they could just as easily be in direct contact with the one of the other.

 Anyway, from the origin of the angular movement between the parts A, B, friction occurs between the distribution washers 50, 52, or that this friction develops between the friction washer 51 and the distribution washer 50, that is to say that it develops between the friction washer 51 and the distribution washer 52.

 In practice, this friction is normally the only one to intervene during a first portion of this angular movement, until the circumferential play JT or JR, depending on whether the operation is in "draw" or in "retro", when absorbed, the elastic members with circumferential action 36 in turn come into action, these elastic members with circumferential action 36 thus only intervening during the next portion, or second portion, of the angular movement.

 However, as a variant, provision may also be made for the intervention of elastic members, and, for example, elastic members of relatively low stiffness, during the first portion of this angular movement.

 Anyway, according to the invention, during the first portion of this angular movement, or, at least, at the end of it, the game J'T or J'R is also absorbed, at least in the embodiment shown, so that the friction washer 53, hitherto ineffective, since it is inserted between two elements wedged in rotation with each other, namely the hub 20 of part B and the distribution washer 52, adds its effects to those of the friction washer 51, a friction then developing between this washer 53 and each of the elements in question, since, its tab 62 being in abutment against one or the other of the teeth 60 of the teeth 59 of the hub 12 which surround it, it is therefore secured in rotation to this hub 12.

 By construction, it is made so that the overall friction which results therefrom is much greater than the initial friction, by being for example multiplied by three with respect thereto.

 Thus, the impact of the circumferential fingers 44T, 44R of the arms 38 of the webs 30 of part B against the corresponding end caps 40 of part A is advantageously braked.

 As will be noted, the stack of washers 35 according to the invention is, axially, relatively compact, which facilitates installation, and it extends along a circumference of relatively reduced diameter, which minimizes the quantity of material necessary for the constitution of the various washers which constitute it.

 Quc, i that it is, the same elastic washer, the washer 49, advantageously and economically ensures there, both the load of the rolling means 21, and both that of the other washers of the stack 35 to which it participates, and therefore of those of these washers which are intended to be the cause of friction.

 In the embodiment shown, the teeth 60 of the toothing 59 of the hub 12 of the part A extend axially from the flange 13 of which this hub 12 is integral as far as the rolling means 21, and they therefore form by themselves the transverse shoulder 22 against which the latter are supported.

 As a variant, in FIGS. 6, 7, the teeth 60 of the teeth 59 of the hub 12 of part A only extend axially on the side of the hub 20 of part B, and no transverse shoulder is provided on this hub 12 for the rolling means 21.

 In addition, in this embodiment, there is provided a friction washer 63 between the washer 53 which thus meshes with play with the hub 12 and the flange 23 of the hub 20, and, likewise, a friction washer is provided. 64 between this washer 53 and the washer 52 which is locked in rotation on this hub 20.

 Finally, in this variant embodiment, the lug 56 ′ which the washer 52 presents for its rotation setting on the hub 20 extends radially, in the direction opposite to the axis of the assembly, while being engaged, as previously , in a recess 57 'of this hub 20.

 For the rest, the provisions are of the type described above.

 In the foregoing, the axial extension of the lug 62 which the washer 53 presents to mesh with play with the hub 12 of the part A is equal to that of this washer 53.

 As a variant, FIGS. 8 and 9, the axial extension of this tab 62 is greater than that of the washer 53 to which it belongs, so that this tab 62 extends not only radially, but also axially.

 Its grip with the toothing 59 of the hub 12 when it is in abutment against a tooth 60 thereof is advantageously increased.

 In addition, in this variant embodiment, this toothing 59, which is of the type described with reference to FIGS. 1 to 5, is also used for the setting in rotation of a washer 50 ′ on this hub 12, in substitution for the previous washer 50.

 Like the washer 53, the washer 50 'has for this purpose a tab 55' which extends not only radially but also axially, but unlike the washer 53, it meshes without play with the teeth 59 of the hub 12, its tab 55 'being engaged without play between the two corresponding teeth 60 thereof.

 In practice, the washers 53, 50 ′ are identical to each other, being systematically arranged one with respect to the other with respect to the washer 52 that they frame.

 These are for example washers made of friction material.

 But this is by no means imperative.

 When the washer 50 'is thus made of friction material, a protective washer 48' is interposed between it and the elastic washer 49.

 As before, this elastic washer 49 in fact extends on the side of the flange 13 of the hub 12, bearing on it either directly, as shown, or by means of a protective washer, as described with reference in Figures 1 to 5.

 As a variant, in FIGS. 10, 11, the elastic washer 49 extends on the side of the hub 20 of part B.

 In addition, in this variant embodiment, the clearance engagement means according to the invention intervene between this hub 20 and one of the washers of the stack 35, this hub 20 comprising, elongated substantially axially, at least one recess 66, and the washer concerned, specified below, comprising a tab 67, which extends axially, and which is engaged with play, in said recess 66.

 In the embodiment shown, the recess 66 thus presented by the hub 20 of the part B is a notch formed at the internal periphery of its flange 23.

 In practice, in this embodiment, the washer which, by the tab 67, meshes with play with the hub 20 of part B is a washer 68 which extends between the flange 13 secured to the hub 12 of part A and a washer 50, which, according to the type of those described above with reference to FIGS. 1 to 5, is locked in rotation on this flange 13.

 At the same time, on the other side of the washer 50 thus locked in rotation on the flange 13 of the hub 12, is disposed a washer 69 comprising a lug 70 which extends axially and which is engaged without play in the recess 66 of the hub 20 of part 13.

 This washer 69 is therefore locked in rotation on the hub 20.

 In the embodiment shown, the axial tab 67, 70 which each of the washers 68, 69 thus comprises is formed by an axial extension of a socket 71, 72, which, integral with this washer 68, 69, forms for this- here a landing.

 The sleeve 71 of the washer 68 is engaged on the hub 12 of part A, and the sleeve 72 of the washer 69 is engaged on the sleeve 71 of the washer 68.

 In the embodiment shown, the washers 68, 69 and the corresponding sockets 71, 72 are made of friction material, and a protective washer 48 is therefore interposed between the elastic washer 49 and the washer 69.

 The axial recess 66 presented by the hub 20 of part B for the engagement with play of a washer can advantageously be produced by broaching.

 In the alternative embodiment illustrated in FIGS. 12, 13, the elastic washer 49 is arranged, as in the embodiment illustrated in FIGS. 1 to 5, with or without a protective washer, between the flange 13 of the hub 12 of the part A and a washer 50 wedged in rotation on this flange 13, and the washer 68, which, by an axial tab 67, meshes with play with the hub 20 of part B, is disposed on the other side of the washer 50 with respect to the elastic washer 49.

 Furthermore, in this variant embodiment, the stack 35 is reduced to these washers 49, 50 and 68, and, between the washer 68 and the flange 23 of the hub 20, a roller stop 74 is interposed.

 Thus, in this alternative embodiment, and unlike the previous embodiments, there is no hysteresis for the first portion of the angular movement between the parts A, B, no specific friction then occurring between them other than the inevitable internal or mounting friction.

 In the variant embodiment illustrated in FIGS. 14 to 16, the resilient washer with axial action that the stack 35 includes to ensure the loading of the rolling means 21 forms by itself any one of the washers, one of which is wedged in rotation on any one of parts A, B and the other of which meshes with play with the other of these.

 In practice, in the embodiment shown, this washer is a corrugated elastic washer 49 'of the type sold under the commercial designation' ONDUFLEX ", and, by at least one lug 55 'which it presents for this purpose axially to its outer periphery, it is locked in rotation on the flange 13 of the hub 12, in the manner of the washer 50 described for example with reference to Figures? to 5.

 This elastic washer 49 'is in contact with the flange 23 of the hub 20 of part B, and, between it and the flange 13 of the hub 12 of part A, is interposed a washer 68 which, by an axial tab 67, meshes , with play, with said hub 20, according to arrangements of the type described with reference to FIGS. 10, 11.

 Thus, in this embodiment, the stack 35 is reduced to two washers, namely the washer 68 and the elastic washer 49 ', and, during the first portion of the angular movement between the parts A, B, the friction between these parts A, B is due to this single elastic washer 49 '.

 The present invention is moreover not limited to the embodiments described and shown, but encompasses any variant embodiment and / or combination of their various elements.

 In the foregoing, the overall circumferential clearance J ′ of the meshing means with clearance intervening between one of the washers of the stack of washers 35 used according to the invention and one of the coaxial parts A, B concerned , measured angularly, is at most equal to the first portion, of value J, of the angular clearance between these coaxial parts A, B corresponding, before the intervention of elastic means with circumferential action of relatively high stiffness, to the only intervention of means friction or, alternatively or in addition, to that of elastic means with circumferential action of relatively low stiffness.

 But, as noted, it may have a higher value.

In all cases, if, as indicated, the first portion of the angular movement between the coaxial parts
A, B extends over 20-, this overall circumferential clearance J 'can, if desired, for example be much greater than 5'.

 Also in all cases, the rotationally entrainment of that of the washers used which meshes with play with one of the coaxial parts A, B is advantageously done very simply by one or the other of the hubs of these, for the benefit of a good use of the available space.

Claims (18)

 1. Damper flywheel for transmission, in particular for a motor vehicle, of the type comprising two coaxial parts (A, B), which, each forming a mass of inertia, are mounted to rotate relative to one another, with intervention between they, radially, of rolling means (21) subjected axially to elastic load means, circumferentially, for at least a portion of their angular displacement, of elastic means with circumferential action (36), and, axially, of a stacking (35) of washers, at least one of which is a friction washer, characterized in that, in combination, on the one hand, the washers of said stack (35) are subjected to the elastic load means (49, 49 ') of the means bearing (21), and, on the other hand, one of said washers is locked in rotation on any one of the coaxial parts (A, B) concerned while between another of them and the other said coaxial parts (A, B) intervene engagement means at play.  2. damping flywheel according to claim 1, characterized in that, one (A) of the coaxial parts comprising a first hub (12), and, integral with the latter, a flange (13), while the other (B) comprises a second hub (20), which surrounds the first, with interposition of the associated rolling means (21), of which a flange (24) is integral, the stack (35) of washers acting axially between said parts coaxial (A, B) is arranged between the flange (13) of the first hub (12) and the second hub (20).  3. Flywheel damper according to claim 2, characterized in that the stack (35) of washers extends through a recess (46) of the second hub (20).  4. Flywheel damper according to any one of claims 1 to 3, characterized in that the stack (35) of washers extends to the right of the flange (24) of the second hub (20).  5. Flywheel damper according to claim 2, characterized in that the intermeshing means play between the first hub (12) and one (53) of the washers, said hub (12) having at its outer periphery a toothing (59), and said washer comprising at its internal periphery at least one tab (62) which extends at least radially and which is engaged with clearance between two teeth (60) of said toothing (59).  6. damping flywheel according to claim 5, characterized in that the washer (53) which meshes with play with the first hub (12) extends between the second hub (20) and a washer (52) fixed in rotation on that -this.  7. damping flywheel according to claim 6, characterized in that, on the other side of the washer (52) fixed in rotation on the second hub (20), a washer (50, 50 ') is arranged in rotation on the first hub (12).  8. Flywheel damper according to claim 7, characterized in that the washer (50 ') locked in rotation on the first hub (12) meshes without play with the teeth (59) thereof by at least one lug (55' ) which extends at least radially.  9. Flywheel damper according to any one of claims 5, 8, characterized in that the axial extension of said tab (62, 55 ') is equal to that of the washer (53, 50') to which it belongs.  10. damping flywheel according to any one of claims 5, 8, characterized in that the axial extension of said tab (62, 55 ') is greater than that of the washer (53, 50') to which it belongs, so that said tab (62, 55 ') extends not only radially, but also axially.  11. A damping flywheel according to claim 2, characterized in that the play-engagement means intervene between the second hub (20) and one (68) of the washers, said hub (20) comprising, substantially axially elongated, at at least one recess (66), and said washer (68) comprising a lug (67) which extends axially, and which is engaged with clearance in said recess (66).  12. damping flywheel according to claim 11, characterized in that said recess (66) of the second hub (20) is a notch formed at the inner periphery of a flange (23) which, integral with said second hub (20), s 'extends radially towards the axis of the assembly.  13. damping flywheel according to any one of claims 11, 12, characterized in that the washer (68) which meshes with play with the second hub (20) extends between the flange (13) integral with the first hub (12 ) and a washer (50) fixed in rotation thereon.  14. damping flywheel according to claim 13, characterized in that, on the other side of the washer (50) locked in rotation on the flange (13) of the first hub (12), is disposed a washer (69) comprising a lug (70) which extends axially, and which is engaged without play in the recess (66) of the second hub (20).  15. A damping flywheel according to any one of claims 13, 14, characterized in that the axial tab (70) of said washer (68, 69) is formed by an axial extension of a sleeve (71, 72), which , integral with said washer (68, 69), forms a bearing therefor.  16. A damping flywheel according to any one of claims 1 to 15, characterized in that one of the washers of the stack (35) is an elastic washer with axial action (49, 49 '), forming the elastic means of load of the rolling means (21).  17. damping flywheel according to claim 16, characterized in that the axial action elastic washer (49 ') forms by itself any one of the washers, one of which is locked in rotation on any one of the coaxial parts (A , B) concerned and the other of which meshes with play with the other of these.  18. damping flywheel according to any one of claims 1 to 17, characterized in that the elastic circumferential action means provided between the two coaxial parts (A, B) concerned only intervening during a second portion of the angular movement between them, the overall circumferential play (J ') of the interlocking means acting between a washer and one of said coaxial parts (A, B) measured angularly, is greater than 5-.