FR2493446A1 - Torsional damper e.g. for friction clutch - includes circumferentially acting elastic plate with deformable arm integral with one support to resist angular movement - Google Patents

Abstract

The torsional damper comprises at least two coaxial parts (A,B) mounted to rotate relative to one another. A circumferentially acting elastic plate resists such relative angular movement and incorporates an elastically deformable arm (29). This arm extends between two support members (34,35) with at least one of which it is integral via a respective root area. These support members are engaged with respective rotating parts (A,B) so as to rotate over at least part of the defined range of relative angular movement. This eengagement may be by means of pins (43). When the damper is applied to a clutch plate, fingers (47) of one support member (35) engage the usual window springs (28A). The inner support member (34) may have a radial slit, the inner and outer support members (34,35) may be relatively axially offset, and the outer support member may be corrugated to form an axially acting spring.

Description

The present invention relates generally to devices

  torsional dampers. which include

  at least two coaxial parts rotatably mounted one relative to

  port to another, within one. determined angular displacement, and against elastic means capable of acting

  circumferentially between them, hereinafter called elastic means

  circumferential action ticks.

  As we know, one. such a torsion damping device usually enters into the constitution of a clutch friction, in particular for a motor vehicle, one of its

  rotating parts then comprising a. friction disc

  tiné to be joined in. rotation with a. first tree, in.

  practice one. driving shaft, the output shaft of the engine in the case of, for example. motor vehicle, while another of said rotary parts is carried by a hub intended to

  be secured in rotation. with a. second tree, in. practi-

  as a driven shaft, the input shaft of a gearbox

  for example in the case of such a motor vehicle.

  Such a torsional damper. allows in. effect

  ensure a regulated transmission of the appropriate torque

  bent at one of its rotating parts when the other is itself the object of a. torque., that is to say to filter the vibrations likely to arise throughout the kinematic chain, going from the engine to the shafts

  wheel ordered, on which it is inserted.

  Most often, elastic means to action. circum-

  implemented are constituted in their entirety by springs of the coil spring type, which are each individually arranged substantially tangentially to a

  circumference of the whole, and which are, also each in-

  partly, housed partly in a window provided

  in an annular part belonging to one of the rotating parts

  concerned, one. flaccid or one. transverse web for example-

  ple, and partly in a window in a room belonging, parallel to the previous one, to the other of said

  rotating parts, a washer for example.

  The location. such springs in the parts in question

  tion. not without raising serious difficulties, the

  cut windows that it is necessary to practice there to

  accommodate these springs, which will not diminish their resistance

mechanical tance.

  Taking into account the minimum mechanical resistance to

  pect, on the one hand, and the most often weak place

  radially ponible, on the other hand, which do not allow in. uncomfortable-

  ral not implanting springs along two circumferen-

  these distinct, concentric, of the whole, it appears

  what a limit in the number of springs thus susceptible

  bles to be implemented, and therefore, as a corollary; a.s limited

  te in at least some of the operating characteristics

  ment dua torsion damping device conrern.éo To overcome this difficulty, it has already been proposed to implement, for the zonstitution of elastic mroyens with

  circumferential action, at least one elastically de-

formable.

  In the American patent No 2.114o247, it is the totality of these elastic circumferential action means which are

  thus made up of such id_-formable elastic arms, these

  there being in practice two in number, one for the -fon.c-

  tction in. "pulling" of friction, and the other for the function-

  tction in. "retro" of it.

  But, besides that, in this American patent, each of the

  elastically deformable arm results from the winding. Hey-

  cross section bar. substantially square transverse and that such a helical winding is difficult in practice to achieve, such an elastically deformable arm extends therefrom

  first end, in practice its internal end, by the-

  which, this end being shaped as. square, it is

  radially anchored in one of the rotating parts of the device

  tif torsion damper concerned, at a second end, in practice sound. external end, through which this one

  being shaped as a hook, it is coupled to the second

say rotating parts.

  Thus, for at least one of its ends, and it

  sound git. inner end, one. such arm 6lastically de-

  formable is clamped, so that, in operation, and taking into account the deformation movements which it knows during

  of one. such functioning, problems of "fretting" and of

  sure do not fail to develop in the area of encas-

very corresponding.

  Likewise, at its other end, and this is its ex-

  external end by which it is coupled to one of the

  rotating parts of the torsional damping device

  born, problems of "fretting" and wear do not fail in operation to develop, the coupling contact between said end and said rotary part being made

  articulated, and therefore with friction.

  In French patent No 1,423,139, only a part

  elastic circumferential action means used

  vre consists of an elastically deformable arm.

  In. in addition, this elastically deformable arm is cut from a thin blank, arranged transversely, its cross section having an axially reduced dimension compared to that of its radial dimension, so

  that the axial size due to such an arm is minimal.

  However, the coupling of this elastically deformable arm to the two rotary parts between which it is interposed is

  made, in this French patent No 1,423,139, by articula-

  tions, so that, in service, and as before, it does not fail to develop, to the right of these joints,

  fretting and wear problems.

  The present invention generally aims to

  throw a provision to avoid these drawbacks and

  further leading to other benefits.

  More specifically, it relates to a device

  torsional damper, in particular clutch friction

  ge, of the kind comprising at least two parts: s coaxial mon-

  rotating tees relative to each other, within the limits of a determined angular movement, and against elastic means, called elastic means with circumferential action, which are capable of acting circumferentially between said

  rotating parts, and which comprise at least one. elasticated arm

  only deformable cut from a thin blank, this torsion damping device being characterized in that said elastically deformable arm extends between two load-bearing elements with at least one of which it is connected by one. integral with a rooting zone, one of said carrier elements being able to be secured in rotation in a positive manner with one of said rotary parts, and 1 '

  other of said load-bearing elements being provided with drive means

  able to link it in rotation to the other of said rotary parts for at least one range of said angular clearance between said rotary parts. These drive means can also be joining means. intervening positively for

  both directions of rotation., throughout the

  angular beating between the rotating parts concerned.

  But it can also be a matter of drive means acting unilaterally only for one or the other.

  of these directions of rotation, and for a range only of said de-

angular beat.

  Anyway, in operation, none. problem of "fretting", corrosion or wear is not to be feared in the

  rooting zone of the elastically deformable arm set.

  work, this rooting zone being in continuity of my-

  with this arm and the supporting element between which it is

  established, without any friction contact.

  Therefore, for this rooting zone at least, the

  operating characteristics of the assembly are

  steadily stable over time, without any change

  due to possible corrosion for example.

  Preferably, the elastically deformable arm becomes

  rope of one. standing alone by a rooting zone with each

  load-bearing elements between which it extends.

  Anyway, being thin, the blank in which it is cut does not significantly modify the axial size of the torsion damping device concerned; being in addition able to transmit to itself, between the two rotary parts constituting this device, the torque applied to one of them, for low values of this couple, in one direction or the other, it advantageously makes it possible to free the space usually occupied by springs of the spring type

  for this same function.

  The space thus freed can for example be made available

  fit for better implantation of other sub- springs

  suitable for higher torque values, and / or

2493 A46

  better, more modulated distribution of the intervention. of these

  springs as a function of the angular travel, and therefore of the

  ple, between the two rotary parts concerned.

  As a variant, it can also advantageously be upgraded. profit for the installation of additional springs

  allowing the maximum torque capacity of the device to be increased

  positive torsional damper concerned.

  Thus, in this case, it is advantageously possible, starting from conventional constituents, to produce, by adding a blank. in which an arm is cut according to the invention

  elastically deformable, torsion damping devices

  sion with different characteristics, which is

  favorable to a rationalization of the manufacturing of these devices

  tifs, and therefore to obtain them at the lowest cost of these.

  The blank thus used can be flat.

  Alternatively, the two load-bearing elements between which the elastically deformable arm of this blank extends can be axially offset one. compared to each other, which of

  one part is favorable to good mechanical strength of the assembly

  ble, improving the blistering resistance thereof, and

  which, on the other hand, eventually allows the elastic arm-

  deformable to overlap axially, in service, one and / or the other of its load-bearing elements, the working capacity

  of this arm thus being advantageously extended.

  In addition, according to a development of the invention.,

  friction means, with which are associated means of

  elastic rage with axial action, being provided between the rotary parts constituting the torsion damping device

  concerned, the blank from which the elastic arm is cut -

  deformable implemented is used for the consti-

  tution. such elastic clamping means with axial action.

  For example, one. at least bearing elements of the arm

  elastically deformable may, circumferentially, present

  ter corrugations, like elastic washers

  sold under the commercial designation 'OlNDUFLFEX'; in Varian.-

  te, or jointly, said plastically deformable arm can

  itself present such undulations.

  In this case, the blank in which the elastic arm is cut-

  tically deformable fulfills a double function, which is to

  one part to ensure the transmission of a couple of one of the

  rotary ties concerned to each other, and on the other hand to

  participate in the development of a. hysteresis effect between these parts, that is to say of a differentiation, for the same angular displacement value between said parts, between on the one hand the value of torque for an increasing evolution of this couple: and, on the other hand, the torque value for a

  decreasing evolution this one.

  The number of parts to be used for this purpose is reduced.

  advantageously found reduced therefore In another development of the inventio.n, this blank can participate in a third function, which is that of the radial centering relative to each other of the two rotary parts concerned

  To this end, for such centering, the uDe of said par-

  rotating ties has at least two xial center tabs

  trage by which it is engaged with one of the elemrents carriers of the elastically deformable arm taneis that the other of said carrier elements is integral with the ancestor of said

parts.

  In all cases, the load-bearing elements have a confi-

  any guration; it can be for example, but not.

  washers, which are circumferentially

  continuous or open by a more or less wide slit.

  In all cases also, the thickness of the blank in

  which is cut the elastically deformable arm is sim-

  fully adapted to the torque to be transmitted: for a configuration

  tion. given corresponds to a given distribution of constraints

  and, the conditions being equal, the couple above

  what can be transmitted depends on the thickness alone.

  But the same matrix is advantageously suitable for the de-

  cutting blanks of different thicknesses.

  The characteristics and advantages of the invention stand out

  will derive from the description which follows, for

  example, with reference to the accompanying schematic drawings in which:

  Figure 1 is a partial view in. elevation of one. say-

  positive torsional damper. according to the invention; Figure 2 en.est is an axial sectional view, along the broken line II-II of Figure 1; Figure 3 is an elevational view of the single arm blank

  elastically deformable that includes this cushioning device

  torsion torch, shown in isolation; FIG. 4 is a view in axial section of this blank., following the line IV-IV of FIG. 3; Figure 5 is a diagram illustrating the operation of the torsion damping device. according to the invention .; Figure 6 is, on a larger scale, a partial view similar to that of Figure 2, and relates to an alternative embodiment;

  Figure 7 is a partial view in circumferential section.

  tielle, supposedly deployed flat, of this variant of reali-

  sation, along line VII-VII of Figure 6; Figure 8 is a partial cross-sectional view of this alternative embodiment, along line VIII-VIII of Figure 6; Figure 9 is a view similar to that of Figure 6 and corcerne another alternative embodiment .; Figure 10 is a partial cross-sectional view of this alternative embodiment, along the line X-X of Figure 9; Figure 11 is another view similar to that of Figure 6 and relates to another alternative embodiment .; Figure 12 is a partial view in cross-section of this alternative embodiment, along the line XII-XII of Figure 11; Figure 13 is a partial view similar to that of Figure 2 and relates to another alternative embodiment; Figure 14 is, on a larger scale, a partial view

  in cross section of this alternative embodiment.

  before line XIV-XIV of figure 13

  Figure 15 in. is a partial view in elevation,

  vant arrow xv of Figure 13; Figure 16 is a view. elevation of the single blank. elastically deformable arm used in this variant, shown in isolation; Figure 17 is a side view of this blank, according to arrow XVII of Figure 16; Figure 18 is a half-view in similar axial section

  to that of FIG. 2 and relates to another variant of re-

  alization of the torsion damping device. according to the-

  vention .; Figure 19 is a partial view in. elevation. of this variant, along arrow XIX of Figure 18; Figure 20 is an elevational view. a.alogue to that of Figure 3 and relates to an alternative embodiment .;

  Figure 21: partly takes Figure 20, and concerns

  do another alternative embodiment; Figure 22 is an elevational view similar to that

  of Figure 3 and relates to another alternative embodiment.

  In these figures, the torsional damping device to which the invention is applied constitutes, by way of example,

  clutch friction with a shock absorbing hub.

  In the embodiment illustrated by Figures 1

  at 5, this friction. clutch has two coaxial parts

  them, namely an exciting part A and an excited part B,

  rotatably mounted relative to each other, within the limits

  tes of a determined angular movement, and against elastic means able to act circumferentially between

  them, called elastic means with circumferential action.

  The excited part B comprises on the one hand a hub 10, and

  on the other hand a hub cover 11, which extends transversely-

  lying around the hub 10, and which is integral with the latter.

  The hub 10 is suitable for being engaged on one. tree in

  practice one. driven shaft, the gearbox input shaft-

  ses in the case of clutch friction for vehicle

  tomobile. For its rotational attachment to such a shaft, the hub 10 has, at its internal periphery, in the example of

  production. shown, grooves 12.

  The exciting part A comprises two washers 13, called guide washers, which extend transversely around

  of the hub 10, on either side of the hub web 11, at

  tance of it, and which are joined to each other

  by axial balusters 14 passing through with play of the samples

  crures 15 provided for this purpose at the periphery of said veil

hub 11.

  24934tf6 The exciting part A also includes a. friction disc. 17, which is integral with the guide washers 13,

  by the axial columns 14 joining them together

  Ci in the embodiment shown, and which has at its periphery, and on both sides, friction linings

18.

  Such a friction disc is intended to be clamped between two plates integral in rotation with a second shaft, in practice a driving shaft, the motor output shaft in the

  clutch friction for a motor vehicle.

  In the embodiment shown, the friction disc 17 is attached to one of the guide washers 13, and, between the periphery of the assembly thus formed and the hub 10 is disposed a bearing 20 of which is secured a flange radial 21 inserted axially between said assembly and the web

hub 11.

  Between the rotating parts A, B thus formed are provided friction means with which are associated

  elastic clamping means with axial action.

  In the exemplary embodiment, shown, these friction means consist of a friction washer 22 which is carried by a support washer 23 and which is applied to the hub web 11 on the other side of the flange radial 21 of the bearing 20, while the elastic clamping means

  associated axial action consist of an elastic washer

  that 24, of the "ONDUPLEX" type, which, bearing on the corresponding guide washer 13, urges the support washer 23

towards the hub plate 11.

  by axial lugs 25, this support washer 23 is locked in rotation on the guide washer 13 on the side

  from which it is located, these axial tabs 25 being engaged

  gées in notches 26 of this guide washer.

  Elastic means with action. circumferential interpo-

  sés between the rotating parts A, B comprise on the one hand

  springs 28A, 28B, of the coil spring type, and on the other hand a.

  elastically deformable arm 29 cut from a blank of weak

thickness 30.

  The springs 28A, 28B, which are arranged substantially tan.-

  generally at a circumference of the assembly, are, each individually, partly housed in a window 31 of the

  hub cover 11 and partly in windows 32 of the rounds

guide pins 13.

  In practice, the circumferential development of the windows.

  very 31 of the hub wall 11 is greater than that of the windows 32 of the guide washers 13, at. so that for configuration. rest of the assembly, Figure 1 there is, at each end of the springs 28A, 28B, a circumferential clearance

  between each of these ends and the corresponding radial section

  of window 3! in which is housed one. such spring

28A, 28B

  For the direction of rotation. marked with the arrow F at the fi-

  gure 1, this play, measured angularly, has a value J1 for the springs 28A, which are each arranged in globally diametrically opposite positions, and a value J. '!, greater than the previous one, for the springs 28E, which are also each arranged in. globally diametrically opposed positions, in

alternating with the previous ones.

  For the direction of rotation opposite to that of the arrow F, this play, measured angularly, has, for the springs 28A, a value J2 lower than that of the play Jl, and, for the springs

  28B, it has a value J'2 higher than that of this game J2.

  These provisions, which are given here only by way of example, are well known in themselves, and, not being part of the present invention, they will not be described.

in more detail here.

  According to the invention, the elastically deformable arm 29 used in addition extends between two load-bearing elements

  34.35, with at least one of which it is connected in one single

  nant by a rooting zone, In the embodiment shown in the figures

* 1 to 5, the supporting elements 34, 35 form two washers

  concentric, and will therefore be designated as such in the following; there is thus an internal support washer 34 and an external support washer 35, cut from the blank 30,

  like the elastically deformable arm 29, so that this

  this is connected with one. integral with each of these carrier washers 34, 35 by a rooting zone, respectively 36, 37, at the outer periphery of the inner carrier washer

  34, and on the inner periphery of the outer carrier washer

  no 35; it comes in one. and the other case of a zone of

  radial rooting, that is to say a rooting zone which extends substantially radially with respect to the axis of the assembly.

  Preferably, the elastically deformable arm 29 extends

  stretches over 180 to present all the elasticity

haitable.

  In. practical, in the embodiment shown in FIGS. 1 to 5, it extends over a little less than 360, its rooting zones 36.37 to the bearing washers 34.35

  being circumferentially close to each other.

  Over at least part of its length, and in practice over the whole of it, the elastically deformable arm 29 circumferentially runs along the internal support washer 34 in. being separated from the latter by a slot 38; similarly, it circumferentially runs along the outer support washer 35 while being separated from the latter by a slot 39; like the elastically deformable arm 29, these two slots 38, 39 each extend over a little less than 360, and they are in continuity

  with each other by the recess 40 separating one from the

  be the root zones 36, 37 of this arm resiliently

deformable 29.

  In the embodiment shown, the elastic arm-

  tically deformable 29, and the slots 38.39 which flank it,

  have, like the supporting washers 34,35, a. overall outline-

circular.

  But this is not necessarily so.

  The internal support washer 34 is capable of being solida-

  laughing stock in rotation, positively, with one of the parties

rotary A, B.

  In the embodiment shown, it presents

  for this purpose, in diametrically opposite positions, two persons

  holes 42 specific to the passage of pins 43 or the like by which it is secured in rotation to the hub 10 of the rotary part B, while being held in application against

  a transverse shoulder 44 of this hub 10, FIG. 2.

  According to a variant shown schematically in broken lines in Figure 3, for its connection. in rotation with the

  hub 10, the internal carrier washer 34 has, at its

  internal riphery, notches 45, into which can be pushed back, by crimping, material belonging to this

hub 10.

  This provision. facilitates mounting an adjustment of the rest configuration of the assembly, by one. positioning

  angular chosen accordingly to the hub 10.

  The external support washer 35, for its part, is provided

  specific drive means to link it in rotation to the

  be rotating parts A, B, in practice part A in the embodiment shown, for at least one range

  of the angular movement between said rotary parts A, B.

  In the embodiment shown in the figures

  1 to 5, the drive means thus presented by the washer-

  the external carrier 35 comprises at least one radial finger 47 by which said carrier washer 35 is able to come into contact with one of the ends of at least one of the springs 28A,

  28B for the rest configuration of the assembly.

  In practice, in this exemplary embodiment, the washer

  external carrier 35 present, in. overall diametric positions

  trally opposite, two pairs of radial fingers 47 by the-

  which it is engaged without circumferential play on the

spells 28A.

  As well as. will note it, in the example of realization re-

  presented in FIGS. 1 to 5, the blank 30 from which the elastically deformable arm 29, the supporting washers 34, 35, and the radial fingers 47 are cut, extends entirely outside the volume delimited between them by the washers

  guide 13, on the side thereof opposite the friction disc.

  17. It can therefore easily be placed on a friction

  already existing clutch, without modifying the overall structure

  seems of it, and without significantly increasing the clutter-

axially.

  It is the same, if, as a variant, it is arranged on the side.

friction disc tee. 17.

  Furthermore, as will also be noted, in this embodiment firm, the supporting washers 34, 35 are de-

  axially aligned with each other.

2493A46

  In. practical, the stiffness of the elastic arm-

  deformable 29 is less than that presented by each

  cun. individually the springs 28A, 28B.

  In practice also, the stiffness of each spring 28B is greater than that of each spring 28A.

  In operation, when, for operation in.

  drawing of the assembly, the direction of rotation. of said set being

  that marked by arrow F in FIG. 1, a. couple is ap-

  pleated following an increasing evolution in part A, this cost

  ple is first transmitted, in one. first time, at. the

  part B, by the only elastically deformable arm 29.

  In. effect, the bearing washer 35, to which the arm

  elastically deformable 29 is linked by one of its extremi

  tees, is itself linked in rotation, by its shortened fingers

  dials 47, with the springs 28A, and therefore with the guide washers 13 of the exciting part A, and, taking into account the stiffness of these springs 28A, only then yields elastically the

elastically deformable arm 29.

  On the diagram of figure 5, on which one. has plotted, on the abscissa, the angular movement D between the rotating parts A, B, and, in. ordered, the torque C transmitted from one of these parts to the other, the curve representative of this

  first operating phase is a straight line I, which, not

  health by the origin, has a slope proportional to the stiffness

  of the elastically deformable arm 29.

  This first phase of operation continues until

  that, for a value D1 of the travel, the circumference

J1 is absorbed.

  The springs 28A then enter. action.

  But, coming to bear, therefore, by their front end in the direction of rotation concerned, against the corresponding radial edge of the window 31 of the hub plate 11

  in which they are housed, they cease, by this extremi-

  front tee, to circumferentially drive, in the same direction, the corresponding radial finger 47 of the carrier washer

external 35.

  It is therefore therefore immobilized in relation to

  to the hub web 11 in this embodiment.

  The curve representative of this second phase of operation

  tction is a straight line IIA, which comes in continuity with the previous straight line I, and whose slope is proportional to the only stiffness of the springs 28Ao This second phase of operation continues until this view, for a value D2 of the angular movement between the parts A, B, the clearance I'l associated with the springs 28B is

  its absorbed turn and that these springs 28B then enter equally

lying in action

  The curve representative of this third phase of fon.c-

  tionnernent is a line IIB which is in% continuity with the line ILA preceding and whose slope is proportional to

  the cumulative value of the stiffnesses of the springs 18A and 18B.

  and this third phase of operation continues until

  that at the final value D3 of the travel, for which there is a positive direct drive of the excited part B by the exciting part A, either that the springs 28A, 2aB are then saturated, or the axial columns 14 are then in contact with the corresponding radial edge of the scales

  15 of the hub web 11 which they pass through.

  for a decreasing evolution of the couple between the

  parts A, B, corresponding to a so-called "retro" operation of the assembly, a process opposite to that described above takes place

  develops, the springs 28A bringing the carrier washer ex-

  dull 35 at its initial position, by those of the radial fingers 47 of the latter which lie behind the direction

rotation concerned.

  Thus, overall, the elastically dReformable arm 29

  blank 30 alone constitutes a first stage of cushioning

  relatively low stiffness for the values of

  ple also weak, while the springs 29x, 28B are

  overall kill a second stage of damping, reason

  relatively higher size, for equal cutting values

slightly higher.

  This arm therefore advantageously replaces the springs

  usually implemented for the constitution of such a pre-

mier depreciation floor.

  Of course, in the diagram in FIG. 5, the hysteresis effects due to the washer were not taken into account.

  friction 22, according to which, for the same value of -

  beat, there is a differentiation between the value of

  ple for an increasing evolution of the couple and the value of

  couple for a decreasing evolution of it.

  In the embodiment illustrated in FIGS. 1 to 5, these hysteresis effects develop throughout the

  angular movement between the rotating parts A, B concerning

  born. It does. is not the same in the alternative embodiment

illustrated by figures 6 to 8.

  In. indeed, in this variant, and following a development-

  ment of the invention, the outer support washer 35, and the radial fingers 47 which it comprises, extend in the volume delimited by the guide washers 13, between one of these

  guide washers and the hub plate 11, and this washer-

  the external carrier 35 constitutes by itself the elastic clamping means with axial action associated with the friction washer 22, in substitution for the elastic washer

axial 24 previous.

  For example, and as shown in Figures 6,7, this-

  the outer support washer 35 comprises circumferentially,

  like the axial elastic washer 24, corrugations.

  As the previous axial elastic washer 24, and in substitution. to this, the outer support washer 35 involves the friction washer 22, and so

  uniform throughout the angular movement between the

  rotating ties A, B, both during the first damping stage

  formed by the elastically deformable arm 29, that during the se-

  cond damping stage formed by the springs 28A, 28B.

  Furthermore, in this embodiment, for its soli-

  darisation in rotation to the hub 10, the supporting washer

  dull 34 is opened by a radial slot 49, FIG. 8, and

  its internal periphery has a profile similar to that of the

  internal return of the hub 10, so that it is able to be

  engaged on the same tree as him.

  The hub 10 comprising, for engagement on such a shaft, splines 12 in the embodiment shown,

  the inner periphery of the inner carrier washer 34

  therefore carries, in this case, teeth 50 having transversely

  the same profile as said grooves 12.

  Because of the slot 49 which it comprises, its elasticity

  clean is enough to guarantee one. engagement without play on the ar-

  bre on which the hub 10 is jointly engaged.

  It is therefore, in this embodiment, through

  diary of this shaft, not shown in the figures, that the external support washer 34 is secured in rotation to the

hub 10.

  No other means of joining is in fact planned

  between such a supporting washer 34 and a hub 10.

  In the alternative embodiment illustrated by the figures

  9 and 10, the outer support washer 35 is, as before,

  ment, provided with corrugations and therefore constitutes a washer

  elastic to action. axial type "ONDUFLEX".

  But the elastic washer with axial action thus constituted

  killed intervenes between, on the one hand, the guide washer 13 concerned, and, on the other hand, a friction washer 51 linked in rotation to this guide washer 13 by lugs

  axial 52 which, crossing with clearance the carrier washer ex-

  dull 35, and without play said guide washer 13, are, au-

  beyond this, riveted on this guide washer 13,

figure 9.

  Thus, the hysteresis effects due to this friction washer 51 only develop insofar as there is a relative rotational movement between the carrier washer.

  outer 35 and the guide washer 13 against which this

this is applied.

  That is, in this embodiment., Such

  hysteresis effects only develop during the intervention

  tion of the second damping stage formed by the springs

28A, 28B.

  On the contrary, in this embodiment, no

  such friction is associated with the first stage of damping

  formed by the elastically deformable arm 29, and therefore

  no. hysteresis effect only develops during the intervention

tion of it.

  To ensure its return to the initial position after a relative rotation relative to the guide washer 13, the

2493 4; .6

  external bearing washer 35 has, beyond its radial fingers 47, an axial tab 54 and the latter is engaged with

  clearance in a notch 55 provided for this purpose at the periphery

hub disc 11.

  In the alternative embodiment illustrated by FIGS. 11, 12, the external support washer 35 still forms, as before, an elastic washer with axial action, but the friction washer 51 with which it cooperates is suspended by radial arms. 56, on the outskirts of

  the guide washer I concerned 13.

  In addition, the axial tabs 54 of the carrier washer are engaged, with play, in radial extensions

  61 of the windows 31 of the hub veil J.1.

  Finally, in this variant embodiment, the elastic arm-

  tically deformable 29 constitutes elastic clamping means

  tick with axial action, this plastically deformable arm 29 being for this purpose circumferentially affected by undulations,

  like the external support washer 35.

  It is thus used to apply elastically,

  against a shoulder 57 of the hub 10, a friction washer-

  ment 58 which intervenes when there is a relative rotation between this elastically deformable arm 29 and this hub 10, and from which it therefore results from hysteresis effects throughout the

  first damping stage constituted by said elastic arm-

deformable 29.

  As before, the external support washer 35, by its condulations, then ensures the development of

  hysteresis during the intervention of the second damping stage

  formed by the springs 28A, 28B.

  But, in this case, these effects can advantageously, if

  desired, be differentiated from those developed during the inter-

  vention of the first damping stage formed by the arm

  elastically deformable 29, since of different origin.

  The same result can be obtained by the radial arms 56 if these, in substitution for the undulations of the external support washer 35, are elastic and stress the latter

  in, irection of the guide washer 13 in contact with the-

what it is.

  In all cases, the radial fingers 47 of the external support washer 35, which are engaged with springs 283, as before, ensure the return to initial positioD

  of this external support washer 35 during the return to

  rest figuration of the assembly In the foregoing, it has been assumed that the hub plate 11 was integral with the hub 10, the friction, of the clutch concerned therefore comprising only two rotary parts A, Bo Mais, such that i !! ustré by fiCgures 13 to 17, the invention applies iiue as well in case, the veil of naoyeu l! being rotatably mounted around the hub 10, in the lyiites of determined meshing means, not detailed in the figures la

  friction. d'-emraya-_e concerns coort three parts coaxia-

  the rc-taives two by two, namely a part A, formed corute previous to a friction disc 17 and guide washers 13, one of these guide washers being able to form the web of such a friction disc , as shown, an intermediate part C, formed in practice by the hub web 11, and a part B formed, in this case, by the sole

hub 10.

  In such a case, part C forms, with respect to the part

  B, which remains an excited part, an exciting part.

  According to the invention, the elastic means with circular action

  conferred between this exciting part C and this excited part B are, as before.

  by an elastically deformable arm 29 established between two-elements

  bearing elements forming, in the realiscition example, two washers, one internal 34, the other external 35, said elastically deformable arm 29 being connected in one piece with at least one of said washers, and, in the embodiment, represented, with each of these, by a radial rooting zone As above, the internal support washer 34 is capable of being secured in rotation in a positive manner with

  the excited part B, in practice the hub 10, and, in the example

  ple of embodiment shown, its internal periphery comprises for this purpose a profile, generally polygonal, complementary to a range 59 of the hub 10 suitable for such a profile, FIG. 15. Together, the external support washer 35 is provided with drive means suitable for linking it in. rotation with the exciting part C, in practice the hub plate 11, for the entire angular movement between this exciting part C and the excited part B. For this purpose, in the embodiment shown, the external support washer 35 has , at its periphery, a plurality of axial tabs 60, which are each engaged, without play, in a radial extension 61 of a window 31 of the hub plate 11, and which, beyond this, are each folded radially towards the axis of the assembly, for

  the axial maintenance of the blank 30 concerned.

  As before, a friction washer 62 can in-

  keep between, for example, the internal bearing washer 34, which is linked in rotation to the hub 10, and the hub plate 11. As will be noted, in this embodiment., the blank 30 implemented according to the the invention provides a floating mounting of the hub plate 11, and, by it and the springs 28A, 28B, of the friction disc 17 relative to the hub 10, both radially, as circumferentially or axially, thus making it possible to very simply alleviate the consequences a possible misalignment between the leading and led trees concerned. In other words, it therefore provides a centering function in this case. In the alternative embodiment illustrated by the figures

  18 and 19, the blank 30 from which the elastic arm is cut

  only deformable 29 is disposed outside the volume formed by the guide washers 13, on the side of the disc

friction 17.

  The internal carrier washer 34 is applied transversely

  Lement against a shoulder 50 of the hub 10, and, as above

  demment, it is properly secured in a posi-

  tive en.rotation with the hub 10 of the rotary part B. But, according to this variant, the drive means associated moreover with the external bearing washer 35 to ensure a connection in rotation to the rotary part A for a range at less of the angular movement have an axial tab 51 which connects it without circumferential play to

  a friction washer 52 inserted axially between lacol-

  radial flange 21 of the bearing 20 and the web 53 of the friction disc 17, said axial tab 51 passing axially through the

  adjacent guide washer 13, through a passage 54 thereof

  Ci, and with a sufficient circumferential clearance to never

  interfere with this guide washer 13 during the debate

angular.

  In practice, the friction washer 52 is intended to intervene jointly with at least part of the second

damping stage.

  For example, and as shown, it presents

  radial fingers 55 by which it is engaged on the res-

  lots 28A of this second damping stage, for intervention

jointly with them.

  It can also, in a manner known in. self, present an axial leg engaged with play in one. passage of the hub plate 11 to also intervene with the springs 28B (not

visible in the figures).

  Anyway, it is thus linked in rotation. to the

  rotary part A for a determined range of travel an-

  gular. Da preferably, and as shown, the axial lug 51 connecting this friction washer 52 to the outer support washer 35 of the elastically deformable arm 29 comes from a single piece of this friction washer 52, and it is engaged, without play circumferential, in a. simple recess 56 that presents for this purpose at its outer periphery said

  external support washer 35, figure 19.

  The configuration of the blank 30 is thus advantageous.

* particularly simple.

  In the above, by friction washer of course means both a single washer and a washer

  carrier fitted with a friction lining.

  As will be noted, in all forms of realization

  tion described above, the elastically deformable arm 29

  intervenes as well for a direction of rotation as for the

  be. In addition, its effects are identical in both of these directions of rotation, except in the case, to a certain extent, o, having circumferentially undulations, it jointly constitutes an elastic washer with axial elasticity. In fact, in such a case, the undulations which it presents gradually tend to deploy, and therefore to reduce their effects, as the transmitted torque increases, during a pull operation of the assembly. , while, during retro operation of said assembly, they on the contrary gradually tend to tighten, and therefore to

  accentuate their effects, as the couple trans-

put decreases.

  But, for the other cases, in the preceding embodiments, if the radial fingers 47 of the external support washer 35 are not rigorously implanted in pairs in

  diametrically opposite positions of one of these pairs at the other

  for reasons of adaptation to the gdometri- configuration

  clean of the whole, there is a symmetry in the repar-

  stress distributions in the elastically deformable arm

  29, for one direction of rotation and for the other.

  However, it turns out that for at least some applications,

asymmetry is desirable.

  This is particularly the case for clutch friction for

motor vehicles.

  Indeed, such clutch friction is interposed between on the one hand a driving shaft, which forms the output shaft

  of a motor, and which, for neutral, is the object of oscillating-

  cyclic conditions of moderate amplitude to be absorbed, and on the other hand a driven shaft, which forms the input shaft of a

gearbox.

  However, this one, because of its internal friction, opposes

  a certain friction drive torque.

  It follows that, in service, the rest configuration

  of this, or dynamic zero, is shifted circular-

  relative to its rest configuration when it is

isolated, or static zero.

  In other words, in service, and for a total amplitude of

  defined travel, the travel of friction.

  port to its configuration. rest, is more important in one.

  meaning, which corresponds to operation in. pulling the assembly only in the opposite direction, which corresponds to operation in

retro of said set.

  FIG. 20 illustrates an embodiment of the invention.

  tion more particularly suited to such an application.

  In practice, in this embodiment, two elastically deformable arms are circumferentially

  end to end by having a common load-bearing element.

  First of all, from the inside inwards, a

  elastically deformable arm 29, which extends between two elements

  load-bearing elements 66.66 ', then an elastically deformable arm

  29 'which, in continuity with the previous one, extends between the element

  carrier 66 'and a carrier 68, in the manner of a

  spiral that closes on itself.

  In the embodiment shown, each of the elements

  load-bearing elements 66,66 'is reduced to a fork formed by two radial fingers 47, for its engagement, as previously on the springs 28A of the second damping stage, such as

  shown schematically in broken lines in Figure 20.

  But, if for the carrier element 66 this engagement on the corresponding spring 28A is done without circumferential play, it is not the same for the carrier element 66 'vis-à-vis the

corresponding spring 28A.

  Indeed, for this one, the engagement on this spring 28A

  is done without circumferential play for one of the ends of the

  said spring 28A, which is the upstream end for the direction of

  rotation of the assembly corresponding to operation in. ti-

  rage, as indicated by the arrow F in FIG. 20, and with a circumferential clearance J3 for the other end of said spring

  28A, which in. is the downstream end for the direction of rotation at.

  question. For reasons that will appear below, the tranche

  outside of the supporting elements 66,66 ', between the fingers

  dials 47 of these, is also circular in outline.

  The elastically deformable arm 29 is connected in one

  holding with its supporting elements 66,66 ', by a zone of

  rooting 69.69 'which, in the embodiment shown

  tee, extends substantially circumferentially, in continuity

  with this elastically deformable arm 29.

  Likewise, the elastically deformable arm 29 ′ is connected in one piece with the carrying element 66 ′, by a zone of

  rooting 70 which extends substantially circumferentially-

  lying in continuity with this elastically deformable arm 29 ′; on the other hand, its rooting zone 36 with the carrier element

  68, by which it is connected in one piece with it

  ci, extends radially, as before.

  This carrier element 68, which is intended, as before-

  ment, to be united in. rotation in a positive way at

  hub 10 of part B, can have any configuration

than.

  It is not necessarily a washer.

  In the embodiment example. represented, it does not form, to

  As an example, only a fraction. of such a washer.

  As before, the whole is cut in the same

blank 30.

  As will be noted, and for a better distribution of the stresses, the slot 38 circumferentially separating the elastically deformable arm 29 ′ from its carrying element 68 forms, at its blind end, a bloom 72, which is

  of generally circular outline, and which is slightly ex-

  centered in. direction of the axis of the assembly.

  During a draft operation of a damping device

  twist weaver. equipped with such a blank, only is from a-

  edge driven by part A thereof, and following the arrow

  che F of FIG. 20, the carrier element 66.

  Indeed, due to the circumferential clearance J3 separating at rest the spring 28A corresponding its radial finger 47 downstream in the direction of rotation, concerned, the carrier element 66 'is, during this first phase of operation, the object

  no solicitation from this spring 28A.

  therefore, during this first phase of operation-

  ment, the elastically deformable arms 29 and 29 ′ are jointly urged one and the other, in series with each other, between, on the one hand the carrying element 66, and on the other

the carrier element 68.

  This first phase of operation continues until

  absorption of circumferential clearance J3.

  From this moment, in. indeed, the carrier element 66 'is at its. tower subject to a drive action of the

part of the corresponding spring 28A.

  Therefore, although remaining bandaged and continuing thereby

  to add its effects to those of the elastically deformed arm

  table 29 ', the elastically deformable arm 29 does not continue to be stressed, since it extends between two carrying elements 66, 66' which are both jointly driven by the rotary part A. On the other hand , for retro operation of the device

  torsional damper. concerned, only the elastic arm intervenes-

  tically deformable 29 ', between the load-bearing elements 66' and 68.

  Indeed, for such a retro operation, the elements

  supporting frames 66,66 ′ are from the outset jointly driven by the rotary part A, and the elastically deformable arm 29 is therefore from the outset excluded from any stress. Furthermore, in this embodiment, by the

  circular outline of its edge between the fingers 47 of the elements

  carriers 66.66 ', the blank 30 set. artwork lends itself-

  tagging the centering of one of the rotating parts concerned

  born, in practice part A in the case of a device

  torsion damper of the type described above.

  It suffices, in fact, that, for its centering, and such that

  shown schematically in broken lines in FIG. 20, this part

  tie-rotary A has at least two axial tabs of cent.-

  trage 73, and that by these it is radially in. taken with these load-bearing elements 66,66 ', between the radial fingers

  47 of these, as shown.

  Indeed, for these centering tabs 73, the carrier elements 66, 66 'then form contour support zones

  circular allowing the rotation of the part A concerned.

  for example, the axial centering tabs 73 that pre-

  then feels this rotary part A can come from a

  in one piece with the guide washers 13, being

  formed by a part of the lip formed on the occasion of the window of such a guide washer in which is

housed the corresponding spring 28A.

  Anyway, thanks to such centering, which may be necessary if that provided by the springs 28A, 28B n. '

  is approximate, which is usually the case, due.

  corresponding circumferential and radial clearances, there is

  advantageously no friction or play at the level of the bearing 20.

  In the embodiment of FIG. 20, the rooting zones 69, 69 ′ by which the elastically defined arm

  formable 29 connects with one. only holding on to its elements

  teurs 66,66 'extend circumferentially.

  This is not necessarily so.

  On the contrary, and as illustrated for example in FIG. 21 for the rooting zone 69 ′, these rooting zones

can extend radially.

  We. note that in this case such a rooting area

  is circumferentially offset from the input means

  drag, namely the radial fingers 47, associated with the element

corresponding carrier.

  This provision may, at least for certain applications,

  tions, be advantageous, especially in. what concerns the re-

  partition. corresponding constraints within. of the blank 30.

  When such a circumferential offset does not exist, as

  this is the case in the previous realizations, the area of.-

  rooting of an elastically deformable arm is radiated

  also to the right of the drive means associated with the element

corresponding carrier.

  FIG. 22 illustrates an alternative embodiment, for the

  which a single elastically deformable arm 29 is put in.

  work, and in which this elastically deformable arm 29 is connected in one piece to one. load-bearing element only 1 '

one of its ends.

  In the embodiment shown, this is a

  internal support washer 34, that the arm resiliently deforms

  table 29 runs circumferentially, in, being separated by a slot 38 whose blind end forms a blooming

eccentric circular outline 72.

  At its other end, the elastically deformable arm 29 has, at its outer periphery, a recess 80, by which, as shown schematically in broken lines, it can be

  in engagement with a carrier element 81 integral with one of the

rotary ties concerned.

  Such an embodiment is particularly suitable -

  torsional damping devices with three

  rotating parts A, B, C, as described with reference to the

  gures 13 to 17, - and in particular in the case of friction of em-

  clutch intended for equipping a. industrial vehicle.

  The elastically deformable arm 29 according to the invention can then be implemented for example between parts B and C, the support element 34 being secured in rotation with

  positively to hub 10 of part B, as before

  ment, while the carrier element 81 is formed by a lug provided axially in. protruding for this purpose on the hub cover 11 of part C and therefore constitutes by itself the own drive means for binding it in. rotation to said part C.

  The present invention is moreover not limited to

  of achievement described and shown, but includes all

  te variant of execution and / or combination of their various elements.

  for example, the drive means associated with a. elec-

  carrying an elastically deformable arm can be

  unidirectional, to intervene only for one direction of rotation

tion of the whole.

  Alternatively, when these drive means comprise radial fingers, there may be one, on the first side, for one. first direction of rotation, and another, of a second

  side substantially diametrically opposite to the first, for the other

be direction of rotation.

  The present invention is also not limited to the case where

a single blank 30 is used.

  On the contrary two or more blanks 30 can be associated

  ciés. It may for example be an association within which, the blanks 30 concerned being simply juxtaposed, the corresponding elastically deformable arms work

in parallel.

  In such a case, the blanks 30 used are preferably

  rence arranged head-to-tail in pairs, the blank 30 of such a pair being turned 180 over the other blank 30

  of this pair, to avoid displacement of the center of the

  seems in. operation, due to the deformation of which the corresponding elastically deformable arms are subjected,

  although such displacement, without this precaution, is in.

very weak reality.

  But, the association. blanks 30 can also be done

  so that the elastically deformable arms correspond

are in. series.

  In this case, and in the case for example of a paired association of such blanks, if the innermost carrier element of one of these blanks is secured in rotation to a first of the rotary parts concerned, the carrier element the outermost of the other of said blanks is for example secured to the other of said rotary parts, the outermost carrying element of the first of said blanks being also secured

  to the innermost carrier element of the second of these.

  As a variant, the two blanks have their most internal, or most external, bearing elements linked to each other,

  while their most external or most supportive element

  dull is, for one of these blanks, secured to a first of the rotary parts concerned, and, for the other of said

  blanks, secured to the other of said rotary parts.

Claims (24)

CLAIMS. 9-   1) Torsion damping device., In. particular money   tion of the clutch, of the kind comprising at least two coaxial parts rotatably mounted relative to one another, in   the limits of a determined angular movement, and   against elastic means capable of acting circumferentially   between them, hereinafter called elastic action means. circum-   ferric, said elastic action means. circumference.   with at least one elastically deformable arm   (29.29 ') cut in one. thin blank (30), characteristic   terrified in. that said elastically deformable arm (29,29 ') extends between two load-bearing elements (34-68,35-66,66'-81) with one. at least of which it is connected with one. integral with a rooting zone, one of said load-bearing elements being able to be secured in rotation. positively with one   of said rotating parts, and the other of said elements   teurs being provided with drive means (47,51,81) suitable for binding it in. rotation. to the other of said rotary parts   for at least one range of angular displacement between them this.   2) Torsion damping device according to the claim   tion. 1, characterized in that the elastically deformable arm (29.29 ') spans more than 180.   3) Torsion damping device. according to the claim   tion. 2, characterized in. what the elastically deformable arm   (29) extends over one. just under 360.   4) Torsion damping device.   as claims 1 to 3, characterized in that both   load-bearing elements (34,35) are axially offset one. by compared to each other.   5) Torsion damping device. according to any one   as in claims 1 to 4, and wherein one of the parties   rotary comprises a hub (10) adapted to be engaged on a.   tree, characterized by. what, for its solidarity. in rota-   tion to said hub (10) one of the bearing elements forms a   washer (34) opened by a radial slot (49), and its peri   internal hole has a profile similar to that of the internal periphery of the hub, so that it is capable of being engaged on the same tree as him.   6) Torsion damping device. depending on which one   conch of claims 1 to 5, and wherein the means   circumferential actiQn elastics include. in addition to springs (28A), which are of stiffness greater than that of the elastically deformable arm, and which are arranged sensibly-   tangentially to a circumference of the assembly, ie   characterized in that the drive means associated with a   bearing elements (35,66-66 ') of the elastically deflected arm   formable (29,29 ') comprise at least one radial finger (47) by O10 which said carrier element (35,66-66') is capable of coming into contact with one of the ends of one of said springs (28A) for the configuration. rest of the whole and that is one. only   holding with said carrier element.   7) Torsion damping device according to the claim   tion. 6, characterized in that said carrier element (35,66-66 ')   has at least one pair of radial fingers (47) through which   it is engaged on the spring (28A) concerned.   8) Torsion damping device according to the claim   tion 7, characterized in. what, for configuration. of rest of the assembly, said carrier element (35,66-66 ') is engaged without circumferential play on the spring (28A) concerned, for one of the circumferential ends thereof, and with   a. circumferential clearance for the other of said ends.   9) Torsion damping device according to any one.   as in claims 6 to 8, characterized in that two arms   elastically deformable (29,29 ') are circumferential.   end to end by having one. load-bearing element (66 ') mun ..   ) Torsion damping device according to any one   that of claims 1 to 9, in which there are provided, between   the rotating parts which constitute it rubbing means   ment which are associated with elastic action clamping means. axial, and wherein said friction means   have at least one friction washer (52) linked at.   rotation. to one of said rotary parts for at least one range of angular clearance between them, characterized in. that the drive means of one of the carrying elements of the elastically deformable arm comprise an axial tab (51) which connects it without circumferential play to said washer friction.   11) Torsion damping device. according to the claim   cation 10, characterized in that said axial tab (51) is   from a single piece of the friction washer (52).   12) Torsion damping device according to any one   that of claims 1 to 11, in which there are provided, between   the rotating parts which constitute it, means of rubbing   which are associated with elastic clamping means   with axial action, characterized in that at least one of the elements   bearing elements (34, 35) of the elastically deformable arm (29) constitutes such elastic clamping means with axial action   13) Torsion damping device according to any one   that of claims 1 to 12, wherein there are provided, between   the rotating parts which constitute it rubbing means   which are associated with elastic clamping means with   axial action, characterized in that the elastically deflected arm   formable (29) constitutes such elastic clamping means to action. axial.   14) Torsion damping device. according to any one.   that of claims 8, 9, characterized in that said element   bearing carrier (34,35) and / or said elastically deformable arm   (29) has circumferential undulations.   ) Torsion damping device. according to any one   as in claims 1 to 14, characterized in that, for its   centering, one of the rotating parts has at least two   axial centering tabs (73) by which it is radiated   Lely engaged with one of the load-bearing elements (35,66-66 ') of the   elastically deformable arm (29,29 '), while the other des-   said load-bearing elements (34,68) is integral with the other desi- your games.   16) Torsion damping device according to the claim   tion 15, characterized in that, for cooperation. with such   the axial centering lug (73), the support element (35,66-66 ')   concerned has a circular contour support area.   17) Torsion damping device according to any one   as in claims 1 to 16, characterized in that the area   root (36,37,69 ') by which the elastically deformable arm (29,29') is connected in one piece with one of its supporting elements (34,35,66,66 ', 68- extends radially,   18) Torsion damping device. According to the claim   tion 17, characterized in that said rooting zone (36, 37) is radially in line with the drive means (47,   51.81) associated with said carrier element.   19) Torsion damping device according to claim 17, characterized in. that said rooting zone (69 ') is circumferentially offset from the means   drive (47) associated with said carrier element (66 ').   ) Torsion damping device. according to any one   as in claims 17 to 19, characterized in that, on a   at least part of its length, the elastically deformable arm (29, 29 ') circumferentially runs along the carrying element (34, 35,   68) concerned by being separated therefrom by a slot (38,39).   21) Torsion damping device according to the claim   tion 20, characterized in that the blind end of said Ente   (38) forms a bloom (72) with a generally circular outline.   22) Torsion damping device according to the claim   tion 21, characterized in. what said blooming (72) is   offset in. direction of the axis of the assembly.   23) Torsion damping device according to any one   as in claims 1 to 16, characterized in that the area   rooting (69,69'70) by which the elastically deformable arm (29,29 ') is connected with a. standing alone with one. of   its bearing elements (66,66 ') extends circumferentially.   24) Torsion damping device according to any one   as in claims 1 to 6, characterized in. what the arm   elastically deformable (29,29 ') is connected with a. now   by a rooting zone with each of its supporting elements teurs (34,35,66,66 ', 68).   25) Torsion damping device according to any one   as in claims 1 to 24, characterized in. what one. at   minus the load-bearing elements (34,35) of the elastically deflected arm   formable (29.29 ') forms a washer.   26) Torsion damping device according to the claim   tion 25, characterized in that the two supporting elements (34, 35) of the elastically deformable arm (29) form two concentric washers, each being connected in one piece to the arm   elastically deformable (29) by a rooting zone diale (36,37).