Abstract:
The invention concerns a friction plate ( 15 ) in particular for motor vehicle clutch, comprising a support ring-shaped disk ( 14 ) whereof the outer peripheral part is divided into radial blades ( 70 ) bearing friction linings, in particular axially on either side, each blade ( 70 ) being of the tripod type and having, by means of folds ( 77, 78 ), a central bearing zone ( 76 ) linked to the disk ( 14 ) central part ( 114 ) and two peripheral bearing zones ( 75 ), characterized in that each of the two peripheral bearing zones ( 75 ) is connected ( 214 ) to the disk ( 14 ) central part ( 114 ).

Description:
INTERNATIONAL PATENT APPLICATION NO. PCT/FR99/00161, PUBLICATION NO. WO99/39110 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a friction disc, especially for a motor vehicle clutch. 
     2. Description of Related Art 
     More particularly the invention is concerned with a friction disc of the same type as that described and shown in the document EP-A-0 579 554. 
     That document describes and shows a friction disc comprising a plate for supporting friction liners in the form of a ring, with its outer peripheral portion being divided into radial blades carrying friction liners which are arranged, in particular, axially on either side of the support plate, with each blade being of tripod type and having, by virtue of folds, a central engagement zone which is joined to the central portion of the plate, together with two peripheral engagement zones which are arranged tangentially on either side of the central engagement zone. 
     This design, in which the tripod type blades have a form which is generally symmetrical with respect to a radial axis of symmetry, enables the blades to have as great a resistance to centrifugal force as is desired, with the central engagement zone serving to fasten a first one of the friction liners, while the peripheral engagement zones are arranged to come into contact with the second one of the friction liners. 
     In addition, contact with, in particular, the pressure plate of the clutch is greatly improved by avoiding the situation where the zone in which the friction liners are subjected to the pressure from one or other of the two plates between which the friction disc is gripped, is displaced progressively towards the axis of the assembly, so wear in the friction liners is thus generally even and regular. 
     The design according to the prior art accordingly proposes a standard carrier disc for liners which is able to rotate at high speed while reducing seizing and jamming effects, and is at the same time capable of adopting a conical form. 
     The present invention is concerned with an improvement to a friction disc of the same type as that described and shown in the document EP-A-0 579 554, which in particular gives a further increase in the capacity to resist centrifugal force and/or to resist deformation resulting in variations in operating temperature, these effects most particularly affecting the peripheral engagement zones of each tripod type blade. 
     SUMMARY OF THE INVENTION 
     To this end, the invention proposes a friction disc characterised in that each of the peripheral engagement zones is joined to the central portion of the plate. 
     According to further features of the invention: 
     each tripod type blade has an axis of radial symmetry; 
     each central engagement zone is joined to the central zone of the plate by means of a tangential fold at right angles to the axis of radial symmetry of the tripod blade that constitutes the foot of the blade, and enables the central engagement zone to be offset axially with respect to the general plane of the central zone of the plate; 
     each central engagement zone is joined to the peripheral zones by means of folds which are oblique with respect to the axis of radial symmetry of the tripod type blade; 
     the peripheral engagement zones are offset axially with respect to the plane of the central engagement zone, being parallel to the latter; 
     the peripheral engagement zones lie in the plane of the central portion of the plate; 
     the peripheral engagement zones are offset axially with respect to the plane of the central portion of the plate; 
     each of the peripheral engagement zones is joined to the central portion of the plate by a generally radially oriented band; 
     the connecting band extends substantially parallel to the adjacent oblique fold that joins the corresponding peripheral engagement zone to the central engagement zone; 
     each of the said peripheral engagement zones is joined directly to the central portion of the plate by a connecting band coplanar with the central portion of the plate and the peripheral engagement zone; 
     the connecting bands of two neighbouring peripheral engagement zones which are part of two consecutive tripod type blades, are formed as a single connecting band oriented generally radially; 
     the connecting bands of two neighbouring peripheral engagement zones which are part of two consecutive tripod type blades are independent of each other; 
     the said tripod type blades are arranged in circumferential alternation with a series of radial tongues, each of which has at its free end, by virtue of a fold, a supplementary engagement zone; 
     the supplementary engagement zone is joined to the central portion of the plate by means of a tangential connecting fold at right angles to the axis of radial symmetry of the tongue; 
     each peripheral engagement zone is joined to the central portion of the plate by a connecting band, the radially inner end of which is situated radially inward of the tangential connecting fold of the supplementary engagement zone of the neighbouring radial tongue; 
     each central engagement zone comprises a radially inner portion and a radially outer portion which is narrower in the circumferential direction than the inner portion; 
     each central engagement zone is bounded radially by an arcuate outer edge; 
     each central engagement zone is bounded radially by a rectilinear tangential outer edge; 
     each radial tongue is bounded radially by an arcuate outer edge; 
     the tripod type blades are distributed as two sets of blades, the peripheral engagement zones of the blades of one of the sets and their connecting bands being in the plane of the central engagement zone of the blades of the other set. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Further features and advantages of the invention will appear on a reading of the following detailed description, for an understanding of which, reference is made to the attached drawings, in which: 
     FIG. 1 is a front view of a first embodiment, by way of example, of a carrier plate for friction liners, constituting a friction disc in accordance with the features of the invention, and having, arranged alternately with each other, blades of a tripod type and radial tongues; 
     FIG. 2 is a view similar to that in FIG. 1, showing another version of the first embodiment; 
     FIG. 3 is a view similar to those in FIGS. 1 and 2, showing a second embodiment by way of example of a carrier plate for a friction disc in accordance with the features of the invention which does not have any tripod type blades; and 
     FIG. 4 is a view similar to those in FIGS. 1 to  3 , but shows a third embodiment, by way of example, of a carrier plate for use in constructing a friction disc in accordance with the features of the invention which only has tripod type blades, these being spaced apart in two sets of alternate blades. 
     FIG. 5 is a partial half view showing a torsion damping device equipped with a plate in accordance with the invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     In the following description, components which are identical, similar or analogous to each other are designated by the same reference signs. 
     In the drawings, in order to simplify the description it will be noted that it is chosen to show the friction liners, with which the friction disc is equipped on its two opposed axial faces, in FIG. 5 only. 
     Each friction liner may consist of a continuous annular ring, or it may be divided into blocks or tiles, separated from each other by generally radially oriented slots. 
     Thus, FIG. 1 only shows the carrier plate in the general form of a ring which serves as a support for the friction liners  16  which, with the carrier plate  14 , constitute a friction disc  15 . 
     The plate  14  is a thin sheet metal component formed by pressing and bending. 
     The carrier plate  14  consists essentially of an annular central portion  114  which is situated generally inward in the radial sense with respect to the axis X—X of the plate  14 , while its peripheral outer portion, which lies radially outward of the central portion  114 , is divided or broken into radial blades  70 , of which there are six in this example and which are spaced apart circumferentially at regular intervals about the axis X—X, together with the appropriate number of radial tongues  71  which are arranged circumferentially in alternation with the blades  70 . 
     The central portion  114 , in the sense of this invention, of the plate  14  for carrying the liners is a flat portion which lies in a plane at right angles to the axis X—X. 
     In accordance with a design which is known in particular from the document EP-A-0 579 554, each blade  70  is of the so-called “tripod” type. 
     Reference can also be made to the contents of the document FR-A-2 702 811 or the document U.S. Pat. No. 5,452,783 for information about the alternate arrangement of blades of tripod type with tongues. 
     Each tripod blade  70  has a central engagement zone on which there bears, and is fixed, a first friction liner  16 , together with two peripheral engagement zones  75  for contact with the second friction liner  16 . 
     Each tripod blade  70  has a general symmetry of design with respect to a radial axis R 1 . 
     Thus the two peripheral engagement zones  75  are arranged tangentially on either side of the central engagement zone  76 , which itself has a symmetry of design with respect to the radial axis of symmetry R 1 . 
     In the first embodiment, shown by way of example in FIG. 1, the two peripheral zones  75  of each blade  70  are flat, and are situated in the same plane as that of the annular central portion  114 . 
     The central engagement zone  76  is also a flat zone, but it lies in a plane which is offset axially with respect to that of the annular central zone  114 . 
     To this end, the central engagement zone  76  is joined on the inside, in the radial sense, to the annular central zone  114  of the plate  14  through a tangential fold  77  which extends in a direction which is generally at right angles to the radial axis of symmetry R 1 . 
     Similarly, each of the peripheral engagement zones  75  is joined to the central engagement zone  76  through an oblique fold  78 . 
     The oblique folds  78  are oriented generally radially, but they are inclined with respect to the radial axis of symmetry R, in such a way that each central engagement zone  76  comprises an inner portion, in the radial sense, adjacent to the tangential fold  77 , and an outer portion, in the radial sense, which is bounded by a straight outer edge  200  which is tangential and parallel to the told  77 , which is narrower in the circumferential direction than the inner portion. 
     In the example shown in FIG. 1, each central engagement zone  76  also includes, by way of example, a hole  202  for the passage through it of a rivet for fastening the friction liner or liners. 
     Each tripod blade  70  is joined to the central portion  114  of the plate  14  by its tangential fold  77 , which constitutes the foot, radially on the inside, of the tripod blade. 
     In the embodiment shown in FIG. 1, the central engagement zone  76  and the peripheral engagement zones  75  are also bounded by generally C-shaped cut-out slots  204 , the horizontal branches of which extend tangentially through the oblique folds  78 . 
     Each radial tongue  71  includes at its outer radial end, bounded by an arcuate outer edge  206 , a supplementary engagement zone  74  for a friction liner. 
     The zone  74  of each radial tongue  71  is joined to the annular central portion  114  of the plate  14  through a tangential fold  73 . 
     The tangential fold  73  is generally at right angles to the radial axis of symmetry R 2  of the tongue  71 . 
     More precisely, each tangential fold  73  joins the supplementary engagement zone  74  to an intermediate portion  208 , which constitutes the foot of the tongue  71  and is arranged radially between the annular central zone  114  and the tangential fold  73 , the said foot portion  208  extending the annular central portion  114  and lying in the same plane as the latter, and for example in the same plane as the peripheral engagement zones  75 . 
     By contrast, due to the presence of the tangential fold  73 , the supplementary engagement zone  74  is offset axially with respect to the plane of the annular central portion  114 , and it lies for example in substantially the same plane as the central engagement portions  76  of the tripod blades  70 . 
     Each tongue  71  is bounded circumferentially with respect to the two adjacent tripod blades  70  by two generally radially oriented slots  210 , which are oblique with respect to the radial axis of symmetry R 2 , in such a way that each tongue  71  comprises a radially inner portion and a radially outer portion wider circumferentially than the internal portion consisting of the foot  208 . 
     Each internal portion consisting of a foot  208  also has a hole  212  for the passage through it of a rivet for fastening a friction liner or liners, and in this example the second friction liner. 
     In accordance with the features of the invention, and as can be seen in FIG. 1, each of the peripheral engagement zones  75  is joined to the annular central portion  114  of the plate  14  by a connecting strip  214 . 
     Each connecting strip  214  is formed integrally in one piece with the plate  14 , and it extends in a generally radial direction. 
     More precisely, in the embodiment shown in FIG. 1, each connecting strip is adjacent to the oblique fold  78  that separates the peripheral engagement zone  75 , which it joins to the annular central portion  114 , from the central engagement zone  76 . 
     In this first embodiment, the inner radial end of each connecting strip  214  joins the peripheral engagement zone  75  to the foot  208  of the adjacent radial tongue  71 , and it therefore joins it indirectly to the annular central portion  114 . 
     Thus, each peripheral engagement zone  75  is joined firstly to the central engagement zone  76  by means of an oblique fold  78 , and to the annular central portion  114  by means of the connecting strip  214  which joins it to the foot  208  of a radial tongue  71 . 
     As can be seen in FIG. 1, the base of each slot  210  which lies radially towards the inside is widened, and has a semicircular profile so as to give, at the same time, the configuration of the radial tongues  71  and that of the connecting strips  214 , while avoiding any rupture points in this area. 
     Lugs  79  are arranged tangentially on either side of the tangential fold  77 , and their form is a result of the C-shaped cut-out slots  204 . 
     The lugs  79  are intersected by the folds  78 , and they have a root zone in the plane of a peripheral engagement zone  75 , which in this example is in the plane of the radial tongues  71  and of the central annular portion  114  of the plate  14 . The ends of the lugs  79  are in the plane of the central engagement zones  76 . 
     In the embodiment shown in FIG. 1, and in order to enable it to be incorporated in a torsion damping device, the plate  14  has an elastic, bent central portion which is situated inwardly, in the radial sense, with respect to the annular central portion  114 , and to which the tripod blades  70  and the radial tongues  71  are joined. 
     The central portion includes lugs  131 , a continuous central annular ring portion  132 , and windows  121  which are arranged for the passage through them, with a clearance, of springs  103  of the torsion damper. The windows  121  do not have any flanges, and do not serve for holding the springs. 
     Each of the lugs  131  is bounded on the outside, firstly by a crescent-shaped aperture  60  which extends inwardly of a hole for passage through it of a spacer bar of the torsion damper, and secondly, by a bend line  61 . This bend line  61  is in two parts, on either side of an aperture  60 . 
     The parts of the bend line  61  extend from the aperture  60  to the side edge  124  of a window  121  which is bounded radially on the inside by the ring portion  132 . 
     The lugs  131  lie radially between two consecutive windows  121 , and they terminate laterally in these consecutive windows. 
     The lugs  131  are joined on the inside to the ring portion  132 . It will be noted that the lower corners  221  of the windows are widened in the circumferential sense, in such a way that the lugs  131  are in the form of a thin band of matter, oriented radially and extending between two adjacent corners  221 , to expand radially beyond the corners so as to have two curved portions  223  matching the form of an aperture  60 . 
     It is possible to modify the thickness of the elastically resilient lugs  131  by modifying the form of the cut-outs, and especially the form of the aperture  60  and the corners  221 , and/or the bend angle. It is thus possible to eliminate the corners  221 . 
     The lugs  131  are inclined axially in such a way that the central ring portion  132  is offset axially with respect to the plane in which the central annular portion  114  lies. 
     As will be clear from the foregoing description, the plate  14  is mechanically treated and heat treated to give it the required elasticity. 
     The tongues  71  have a circumferential extent which is smaller than that of the blades  70 , the central engagement zone  76  of which serves for fastening, in this example by riveting, of the second one of the friction liners  16 . 
     The zones  75  lie at the outer periphery of the blade  70 , radially outwards of the fold  77 , and they are arranged to come into contact with the second one of the friction liners  16 . 
     The portion  74  is a supplementary portion for the first one of the friction liners  16 . 
     It will be noted that the cut-outs  204  of any one blade  70  extend in opposite directions from each other. 
     In this example (FIG.  5 ), the first friction liner  16  is adapted to cooperate with the pressure plate  100  of the friction liner, while the second friction liner  16  is adapted to cooperate with the reaction plate  101  of the clutch, which is indicated diagrammatically in broken lines as is the pressure plate  100 , which deforms to a greater extent under heat that the reaction plate. In FIG. 5, the ring portion  132  bears elastically on a damper plate  106  which meshes, with a circumferential clearance, with a hub  107  which is splined internally for coupling it with a driven shaft. 
     On either side of the damper plate  106 , there are arranged two guide rings  104 ,  105  which are joined together by spacer bars (not shown), the springs  103  being mounted in the windows formed in facing relationship in the damper plate  106  and the guide rings  105 ,  104 , one of which is provided with one or more cut-outs  108  for making contact with the hub plate  106  under the axial biasing force exerted by the plate  14 . 
     In this way there is no need to provide an axially acting resilient ring, because of the carrier plate  14  which is configured as a resilient ring. 
     The plate  14 , and therefore the friction disc  15  consisting of the plate  14  and liners  16 , is, thanks to the invention and in this case thanks to the connecting strips  214 , stiffened and made more robust, and is less sensitive to centrifugal force and to thermal effects, without the external peripheral engagement zones  75  being omitted. This solution is simple and inexpensive. 
     The connecting strips  214  may have a double function and may replace the tongues  71  in the manner to be described for the embodiment shown in FIG.  3 . 
     The tongues  71  may be replaced by blades  70  in the manner described for the embodiment shown in FIG.  4 . 
     In the embodiment shown by way of example in FIG. 2, the radially innermost portion of the plate  14  has windows  131  which are generally rectangular in form, but it is not bent elastically, that is to say the central ring portion  132  is situated in generally the same plane as that of the annular central portion  114 . 
     The embodiment shown in FIG. 3 will now be described. In this Figure it can be seen first of all that there are no radial tongues interposed between the tripod blades  70 , of which there are eight consecutive blades in this example. 
     All of the central engagement zones  76  are coplanar, as are all of the peripheral engagement zones  75 . 
     In accordance with the features of the invention, and as in the case of the embodiments described above with reference to FIGS. 1 and 2, each peripheral engagement zone  75  is joined to the annular central portion  114  of the plate  14  by means of a connecting strip  214 . 
     Because of the absence of radial tongues  71 , the connecting strips  214  which join two peripheral engagement zones  75  of two consecutive and adjacent tripod blades are made in the form of a single connecting strip having a greater tangential width, which extends in a radial direction. 
     The holes  212  for passage through them of rivets for fastening friction liners, formed in the preceding case in the radial tongues  71 , are here formed in the widened connecting strips  214 . 
     The central engagement zones  76  and the connecting strips  214  are bounded by cut-outs  204 , which are in the form of walking sticks facing in opposite directions. 
     The radially innermost portion of the plate  14  has cut-outs or windows  131 , oriented generally tangentially and generally of an oblong bean shape, each of which is slightly inclined inwardly in the radial sense with respect to the tangential direction. 
     There are four of these windows, and they are offset circumferentially with respect to the radial axes of symmetry R 1  of the tripod blades  70 . 
     The central ring portion  132  lies in the same plane as the central annular portion  114  without elastic bending. 
     In the embodiment shown in FIG. 4, as in that shown in FIG. 3, there is no radial tongue  71  and the outer peripheral portion of the plate  14  is divided into sixteen consecutive and adjacent tripod blades, which are spaced apart circumferentially at regular intervals about the axis X—X. 
     The sixteen tripod blades are arranged in two alternate series of eight tripod blades  70  and  70 ′. 
     Each of the blades  70  of the first set of eight blades has a general design which is in accordance with the features of the invention. 
     Thus they comprise a central engagement zone  76  and two peripheral engagement zones  75 . 
     By contrast, if such a blade  70  is compared to that shown by way of example in FIG. 1, the central engagement zone  76  is coplanar with the annular central portion  114  of the plate  14 , while the peripheral engagement zones  75  are offset axially with respect to this plane, by virtue of oblique junction folds  78 . 
     Each peripheral zone  75  is joined radially to the annular central zone  114  through a connecting strip  214  which extends radially inwards from the corresponding peripheral engagement zone  75 . 
     The peripheral engagement zones  75  of a blade  70  are coplanar with the central engagement zone  76 ′ of the adjacent tripod blade  70 ′. 
     Thus, all of the central engagement zones  76  are coplanar with each other, and coplanar with the peripheral engagement zones  75 ′ of the blades  70 ′, while all of the central engagement zones  76 ′ of the tripod blades  70 ′ are coplanar with each other and coplanar with the peripheral engagement zones  75  of the blades  70  and with the connecting strips  214 . 
     Each connecting strip  214  thus indirectly assures connection of a peripheral engagement zone  75  of a blade  70  with the central annular portion  114  through an interposed tangential fold  77 ′, which constitutes a foot joining a blade  70 ′ to the central annular portion  114 . 
     The connecting strips  214  are bounded tangentially with respect to a central engagement zone  76  by a radially oriented rectilinear cut-out  230 , while the central engagement zones  76  and  76 ′ are bounded radially on the inside by cut-outs  204  and  204 ′ which are U-shaped, with their central branches being disposed radially inwards in the direction of the axis X—X. 
     In the embodiment shown in FIG. 4, the plate  14  for carrying the friction liners, is of a simplified design, that is to say it does not have the radially inward part beyond its central annular portion  114 . 
     Any method of fastening and configuring the friction liners whatever may be used, and this fastening method may be by riveting and/or adhesive bonding, or by any other suitable means. 
     Thus, the presence of the holes  202 ,  202 ′,  212  is not obligatory in FIGS. 1 to  4 . 
     In this connection, the friction liners may be adhesively bonded on the central engagement zones of the tripod blades and on the inner portions of the tongues. 
     The central engagement zones, in a first embodiment, are totally coated with adhesive. In a second embodiment, the central engagement zones are coated with one or more bands of adhesive extending close to the side edges of each of the said zones, within the latter for fastening of the friction liner concerned in the manner described in the document WO-A-98/44272, to which reference should be made for more detail. 
     In FIG. 5, the plate  14  is fitted between one of the guide rings,  105 , and the damper plate  106 . In another version, the plate  14  may be fitted on the same side as the guide ring  105 , opposite to the damper plate  106 . In that case, a friction device is arranged to act as a spacer between the damper plate  106  and the ring  105 .