FR2692637A1 - Diaphragm clutch mechanism for a motor vehicle. - Google Patents

Abstract

The invention provides a diaphragm clutch (10) comprising a cover (14), a diaphragm, assembly means pivotally securing the diaphragm (20) to the cover (14) and at least one pressure plate. (18) on which the diaphragm bears, in which said assembly means comprise, on the one hand, a washer (26) connected to the cover by a series of rivets (28) which define a constant axial distance between the washer (26 ) and the cover (14) and, on the other hand, elastically deformable means (44) which define a pivoting support (48) for the diaphragm (20). These means consist of a ring ring (44) interposed axially between the diaphragm (20) and the washer (26).

Description

The present invention relates to a diaphragm clutch mechanism,

  especially for a motor vehicle. The invention relates more particularly to a clutch mechanism of the type comprising a first part of generally annular shape called a cover, a second part of generally annular shape called a diaphragm, which comprises a peripheral part forming a Belleville washer and a central part fragmented into radial fingers. by slots to cooperate with a release bearing, assembly means pivotally subjecting the diaphragm to the cover, and at least one plate, called a pressure plate, which is rotationally integral with the cover while being axially movable relative to to it and to which the

  peripheral part of the diaphgragm.

  Document FR-A-2 398 220 describes and represents a clutch mechanism of this type in which the assembly means comprise, on the one hand, a washer which is disposed on the side of the diaphgrag opposite the cover to which it is connected by a series of rivets, which pass axially through the diaphragm and which define a constant axial distance between the washer and the cover, and, on the other hand, elastically deformable means which are arranged between the washer and the diaphragm and which define a support pivoting for the diaphgragm so that the latter is pivotally mounted between a primary support carried by the

  cover and a secondary support carried by these means.

  This document proposes making the elastically deformable means integrally with the washer. This solution is satisfactory from the point of view of the operation of the clutch mechanism insofar as it allows the tightening of the

  diaphragm between its primary and secondary supports.

  However, the unique elastic piece allowing

  to perform the various functions in a tortuous form.

  It cannot be very thick, which would affect its elasticity. In order to remedy these drawbacks, in a simple and economical manner, while retaining the rivets, the invention proposes a diaphragm clutch mechanism of the type defined above, characterized in that the plastically deformable means consist of a ring ring elastic which is interposed axially

between the diaphragm and the washer.

  Thanks to the invention, the washer can be robust and have a large thickness favorable for good geometry of the washer after riveting. This large thickness also facilitates riveting and no longer makes it necessary to have a flange at the internal periphery of said washer. This washer does not need to be treated and can be made from pressed sheet metal because it does not cooperate with the diaphragm. In addition, due to riveting, the dimension between the diaphragm and

  said washer, which makes it possible to choose the crown-

  adequate ring which, advantageously, does not interfere with the rivets which is favorable in particular for a good tilting of the diaphragm This crown may not

to be treated.

  It will therefore be appreciated that all the parts are simple economical and do not require modifying the cover or the clutch pressure plate. We can even make the best use of the available space and increase the radial height of the washer which allows increase the size of the crown ring and better control its elasticity These increases in size of the washer and of the ring crown make it possible to better overcome manufacturing tolerances,

  as well as the need to process the parts.

  Generally speaking, the elastic tightening of the diaphragm between its primary supports is better controlled.

and secondary pivot.

  The increase in thickness of the washer makes it possible to take new advantage of it. Indeed, by forming tabs at the external periphery of said washer, it is possible to create, by cooperation with a counter-stop formed on the reaction plate, means limiting the movement of the pressure plate when the mechanism is not yet attached to the

clutch flywheel.

  This washer can also, using a radial edge, constitute a stop limiting the inclination of the diaphragm when the clutch mechanism is not

  again reported on the clutch flywheel.

  Thanks to these last two arrangements, the tangential tabs are spherically linked in rotation the pressure plate with the cover while allowing

an axial movement of said plate.

  According to other characteristics of the invention: the crown ring is of frustoconical shape and has a rounded edge forming the secondary support for the diaphragm; the rounded edge is an internal edge; the crown ring bears against the lateral face opposite the washer by means of an external edge; the washer comprises means for centering the crown ring; the centering means consist of an external radial edge of the washer, optionally split, which is folded axially in the direction of the crown ring; and each of the rivets comprises a central body delimited axially by two opposite radial shoulders which bear respectively against the faces

  side facing the washer and the cover.

  It will be appreciated that all these provisions are favorable in particular to a reduction in wear and incrustation phenomena at the level of the diaphragm contact.

  crown-rush, the rounded edge favoring this.

  The fact that the rounded edge is an internal edge allows the crown ring to have a large size and not to interfere with the rivets. The arrangement according to the invention therefore makes it possible to take advantage of the washer to conform it by means centering, said washer being able to extend radially, to do this, up to the vicinity of the bosses, which comprises

usually the pressure plate.

  Other features and benefits of

  the invention will appear on reading the description

  detailed which follows for the understanding of which reference will be made to the appended drawings in which: FIG. 1 is a view in axial section of an example of a clutch mechanism produced in accordance with the teachings of the invention; and FIG. 2 is a diagrammatic view on a larger scale of a detail of embodiment of the mechanism

illustrated in figure 1.

  The clutch mechanism 10 illustrated in FIG. 1 forms a unitary assembly and comprises a cover or casing 14 of generally annular shape by means of which it is fixed by screws 16 to the flywheel 12 (or

  clutch plate).

  The mechanism 10 also includes a pressure plate 18, integral with the cover 14 thanks to

  elastic tabs 3, and a diaphragm 20.

  Here in the usual way, each tongue is fixed by riveting at one of its ends to a lug of the pressure plate 18 (FIG. 1) and to the other of its ends at the radial edge of the cover 4 here overall.

shaped like a deep plate.

  In a manner known per se, it is the diaphragm 20 which allows the friction linings of the friction disc 2 to be clamped between the plates 18, 12 of the clutch. The diaphragm 20 comprises a peripheral part 22 forming an elastic washer of the Belleville washer type. By the outer periphery of its Belleville washer, the diaphragm bears on a boss 7, usually divided into a plurality of bosses, of the pressure plate, while by the inner periphery of its Belleville washer, the diaphragm is allowed to be pivotally mounted between two supports, respectively primary and secondary, carried opposite by the cover of

  the clutch as described below.

  The diaphragm 20 also has a central part formed by radial fingers 24, which are separated in pairs by slots from passages or holes 40 formed at the internal periphery of the peripheral part.

22 of diaphragm 20.

  Assembly means securely fasten

  pivoting the diaphragm 20 to the cover 14.

  These assembly means comprise a washer or support ring 26, which is fixed to the cover 14 in the form of a hollow plate by means of a series of rivets.

  28 fixed on the centrally open bottom of the cover 14.

  The rivets 28 are distributed regularly over a

  circumference around the general axis 4 of the mechanism.

  They each consist of a central rivet body which is delimited axially by two shoulders

opposite radials 32 and 34.

  The radial shoulder 32 bears against the opposite lateral face 36 of the washer 26, while the radial shoulder 34 bears axially against the

  internal face opposite 38 of cover 14.

  The rivets 28 thus ensure the fixing of the washer 26 to the cover 14 while maintaining a constant predetermined axial distance between the faces

36 and 38.

  The rivets 28 extend axially through the

  holes 40 provided for this purpose in the diaphragm 20.

  The internal face 38 of the cover 14 carries a pointed annular boss 42, split for mounting the rivets 28, which constitutes the primary support for the

diaphragm pivoting 22.

  As a variant, the primary support may be formed by a ring separate from the cover or be formed by

stamping of the bottom of the cover.

  The assembly means also comprise, in accordance with the invention, an elastic ring ring 44, here of frustoconical shape, which is arranged axially between the internal face 36 of the washer 26 and the face

  lateral opposite 46 of the diaphragm 20.

  The internal radial edge of rounded and convex shape 48 of the crown ring 44 cooperates with the lateral face opposite 46 of the diaphragm 20 to constitute the secondary support for the pivoting of the latter, these

  supports 48,42 being punctual while being located opposite

screws on the same circumference.

  The sharp-angled external radial edge 50 of the crown ring 44 bears against the lateral face 36

opposite the washer 26.

  The ring 44 is crossed centrally with clearance by the rivets 28 and it is centered by means of the rounded external radial edge 52 of the washer 26, which is partially partially axially folded in the direction of the ring ring to form a centering bend 54 of

the crown 44.

  Thus, according to one characteristic, the elastic crown 44, of frustoconical shape, is supported at its external periphery on the washer 26 and at its internal periphery on the diaphragm 20, its inclination allowing a pivoting movement of the diaphragm 20 when the

  friction disc linings 2 wear out.

  It will be appreciated that the washer 26 and the crown ring 44 are robust and relatively thick parts. They can be of pressed sheet metal and not be heat treated. Here these parts have a thickness at least equal and in practice greater than half the size. thickness of the diaphragm 20 and the washer 26 has a large radial height It extends to the level of the internal periphery of the bosses 7 in the vicinity thereof The external edge 52 therefore extends in the vicinity of said boss 7 and allows also to stiffen the washer 26 As a result, the crown ring 44 can have a large radial height, which is beneficial. The characteristic curve of this crown ring is in fact determined in particular by the height of its truncated cone and by its thickness, so that by increasing its thickness one can have a characteristic curve (force of the diaphragm's deformation stroke) with a weak pronation, which allows to have a substantially constant load at

  level of the top of the characteristic curve.

  Here in practice this ring 44 has a thickness greater than the washer 26 to exert after mounting a substantially constant load on the diaphragm in particular when the latter pivots between its primary and secondary supports. An elastic tightening of the diaphragm is thus advantageously and customarily carried out. the tightening is chosen so that the diaphragm 20 remains permanently in contact with its primary support during the operation of the clutch described below, so as not to have loss of lift

pressure plate.

  Thanks to the invention, the elastic load exerted by the crown ring 44 on the diaphragm is well controlled, which makes it possible to reduce the hysteresis phenomena. Of course, the thickness of the crown 44 depends on the applications and may be equal to or less than that of the washer 26. A good tilting of the diaphragm is therefore obtained. As a reminder, it will be recalled that by its cover 14 a clutch mechanism 10 is adapted to be attached to the reaction plate 12 (or flywheel) of the integral clutch, locked in rotation, here on the crankshaft of the internal combustion engine of the motor vehicle, with insertion, between the reaction plate 12 and the pressure plate 18, of the friction disc 2 integral in rotation with the input shaft 5 of the gearbox, while, around the latter is arranged a part, called a clutch release bearing, capable of acting on the end of the fingers 24 of the diaphragm 20 (according to arrow F in FIG. 1), for control by releasing from the clutch thus formed, which is normally engaged, the pressure plate 18 pressing the friction disc 4 against the reaction plate 12 under the stress of the

diaphragm.

  By acting on the ends of the fingers 24, the diaphragm is therefore made to pivot between the crown ring 44

and the boss 42 of the cover 14.

  During this pivoting, the tangential elastic tongues 3, linking in rotation the pressure plate 18 to the cover 14 with axial mobility, urge said pressure plate 18 in the direction of the bottom of the cover 14 which allows lifting of the plate 18 and

  disengage the friction disc 2.

  The assembly of the clutch mechanism that comes

  to be described is carried out as follows.

  We start by making the sub-assembly constituted by the washer 26 and by the series of rivets 28 which are fixed to the washer 26 by crimping their head 31, advantageously provided with a central blind hole.

facilitating crimping.

  Then we thread axially on this sub-assembly the crown ring 44, the diaphgragm 22 and finally the cover 14 by bringing the internal face 38 of the latter in abutment against the radial shoulders 34 of the rivets 28. to crimp the feet 33 with central blind hole of the rivets 28 to ensure the assembly of the assembly while precisely guaranteeing the axial clamping force which is applied to the

  diaphragm 20 by the crown ring 44.

  Indeed, one could have thought of using, as in document US-A-4, 039.059, an assembly part in the shape of a comb, the free ends of the legs of which are folded back. Such a folding does not allow the tightening to be controlled well. diaphragm and requires increasing the clamping force if you do not want the diaphragm to leave its primary support when it

  operation by the clutch release bearing.

  Thanks to the invention, it is therefore possible to reduce the clamping force and thus reduce friction and hysteresis phenomena during the operation of the diaphragm. The assembly of the means for pivotally assembling the diaphragm 20 on the cover 14 therefore consists of a series of components which are of particularly simple shapes and designs, which are inexpensive to produce, and therefore the assembly can also

  be performed reliably and economically.

  Of course, the present invention is not limited to the example of embodiment described. In particular, the diaphragm can be mounted outside the cover as well as the washer 26 and the crown 44, the bosses 7 of the pressure plate 18 passing through. then the bottom of the cover with openings provided for

this effect in this one.

  In all cases, the rivets 28 are carried by the bottom of the cover 14 which has the overall shape of a

  deep plate with its centrally perforated bottom.

  The crown ring can have, in section, a U shape as in the above-mentioned document

US-A-4,039,059.

  The invention makes it possible to obtain other advantages, given that the thickness of the washer 26 can be

as large as desired.

  Indeed, as visible in dotted lines at 152 in FIG. 2, the outer edge 52 can be extended so that said extension serves as a stop for the diaphragm when (in the storage position) the mechanism 10 is not yet attached to the flywheel 12 in order to spare the

tabs 3.

  It is possible to form, at the external periphery of the washer 26, radial lugs 53 projecting radially penetrating with clearance into a recess 54 formed at the bosses 7 of the plate 18 for, in the storage position (mechanism 10 not mounted on the flywheel 12), limit, by cooperation with the edge 55 of the recess 53, the

  movement of the plate 18 and spare the tongues 3.

  In this case, the rim 52 is split to

leg formation 53.

  It will be noted that the edge 55, turned away from the bottom of the cover, constitutes a clean abutment capable of cooperating with the lugs 54 constituting an abutment to avoid damaging the tongues 3 It is therefore created

  means for protecting the tabs.

  Advantageously, the recess 53 is produced by turning and the mounting of the lugs 54 is of the bayonet type. In a simple manner, these legs 54 have a width at most equal to the circumferential distance separating between them two bosses 7 Thus the legs are introduced between two bosses 7, then one proceeds to a relative rotation of the plate 18 relative to the cover il 14 and finally we proceed to the final fixing of the tongues for example to the cover 14, said tongues being able to be riveted in advance to the tabs of the

pressure plate 18.

Claims (9)

  1 clutch mechanism (10) with diaphragm (20), in particular for a motor vehicle, comprising a cover (14), a diaphragm (20) which has a peripheral part (22) forming a Belleville washer and a central part fragmented into radial fingers (24), assembly means pivotally subjecting the diaphragm (20) to the cover (14) and at least one pressure plate (18), which is integral in rotation with the cover (14) while being axially movable by relative thereto and on which the diaphragm bears by its peripheral part (22), in which said assembly means comprise, on the one hand, a washer (26) which is disposed on the side (46) of the diaphragm (20 ) opposite the cover (14) to which it is connected by a series of rivets (28) which pass axially through the diaphragm (20) and which define a constant axial distance between the washer (26) and the cover (14) and, on the other hand, deformable means (44) which are arranged between the washer (26) and the diaphragm (20) and which define a pivoting support (48) for the diaphragm (20) so that the latter is pivotally mounted between a primary support (42) carried by the cover (14) and a secondary support (48) carried by said means, characterized in that said means are constituted by a resilient crown (44) interposed axially between the diaphragm (20) and the washer (26).   2 clutch mechanism according to claim 1, characterized in that the ring ring (44) is supported at its outer periphery on the washer (26) and at its   internal periphery on the diaphragm (20).   3 clutch mechanism according to claim 1 or 2, characterized in that the ring ring (44) is of frustoconical shape and has a rounded edge (48) forming said secondary support.   4 clutch mechanism according to claim 3, characterized in that the rounded edge (48) is a internal edge.   5 clutch mechanism according to claim 4, characterized in that the ring ring bears against the side face opposite (36) of the washer   (26) via an external edge (50).   6 Clutch mechanism according to any one   of the preceding claims, characterized in that the   washer (26) comprises means (52) for centering the crown ring (44).   7 clutch mechanism according to claim 6, taken in combination with claim 5, characterized in that the centering means consist of an external radial edge (52), optionally split, of the washer (26) folded down   axially in the direction of the crown ring.   8 Clutch mechanism according to any one   of the preceding claims, wherein each of   rivets (28) comprises a central body (30) delimited axially by two opposite radial shoulders (32, 34) which bear respectively against the opposite facing faces (36) of the washer (26) and (38) of the cover (14), characterized in that the thickness of the washer (26) is greater than or equal to half of the thickness of the diaphragm (20).   9 Clutch mechanism according to any one   of the preceding claims, wherein the tray   pressure (18) has a boss (7) for supporting the diaphragm (20), characterized in that the washer (26) extends radially to the vicinity of the periphery internal of the boss (7).   Clutch mechanism according to claim 9, characterized in that the washer (26) has at its outer periphery protruding legs (54) radially penetrating into a recess (53) formed at the level of the support bosses (7) , that has the pressure plate (18) for support of the diaphragm (20), said tabs (54) being adapted to cooperate with an edge (55) of said recess for limiting the movement of the plate pressure (18).