Operating member for clutch diaphragm spring, and process for mounting it thereon

For the operation of a diaphragm by a clutch release bearing, there is attached on the diaphragm an operating member comprising in the form of a single piece, an annular collar intended to act by means of a support face on the ends of the fingers of the diaphragm and at least two retaining shoulders adapted to secure it axially on the diaphragm. The retaining shoulders are turned axially in the direction of the support face of the collar. The support face, being curved, accommodates the bending of the fingers of the diaphragm. Advantageously the operating member is fitted onto the diaphragm without stressing any of the fingers thereof.

BACKGROUND OF THE INVENTION 
The present invention relates generally to diaphragm clutches, particularly 
for motor vehicles, such clutches being of the kind in which the resilient 
means provided for their engagement consists of an annular member, known 
as a diaphragm, which comprises a peripheral portion forming a conical 
plate spring integral with a central portion divided into fingers by 
radially-directed slots. 
In order to release clutches of this kind it is necessary to apply a 
disengaging force to the ends of the radial fingers of the diaphragm using 
a disengaging member, usually called a release bearing assembly. 
A release bearing assembly of this kind generally contains a ball bearing 
serving to separate, in respect of rotation, that member of the assembly 
which is intended to act on the diaphragm and which is usually called the 
actuating member, from the member, usually called the control member, 
which is adapted to be operated for this purpose by a release mechanism, 
which is usually a clutch release yoke; the assembly is designed to act on 
diaphragm either by thrust or by traction. 
When it acts by thrust, one of the rings of the bearing, forming the 
actuating member, may very simply bear directly against the ends of the 
fingers of the diaphragm. 
However, in practice, since the diaphragm is generally flat when the clutch 
containing it is in the position of engagement and if the friction linings 
of its friction disc are in new condition, toric contact is desirable 
between this bearing ring and the diaphragm fingers because of the conical 
shape assumed by them through flexion when their ends are subjected to an 
axial thrust applied by the bearing ring. For this purpose the fingers of 
the diaphragm may have a rounded boss at their ends. 
This arrangement, which has the advantage of permitting the use of a 
bearing having a plane actuating edge, has the disadvantage of requiring 
the application of a special configuration to the ends of the diaphragm 
fingers. 
As an alternative, the ends of the diaphragm fingers may be plane, but the 
actuating edge of the bearing must then itself be torically rounded. 
In either case, difficulties may arise on the occasion of an overhaul or 
rebuilding of a clutch entailing the changing of the diaphragm, if the 
diaphragm available for this change is not suitable for the clutch release 
bearing fitted. 
It is therefore desirable, particularly in cases of this kind, to have a 
part available which for the sake of convenience will be called an 
operating member, and which, when attached to the ends of the diaphragm 
fingers, accommodates the bending of the latter during operation, while 
offering to the corresponding clutch release bearing a plane support 
surface. 
When the clutch release bearing acts by traction on the clutch diaphragm, 
it is necessary for it to have an annular collar, which for the sake of 
convenience will be called a support collar or ring, and which is disposed 
axially on the other side of the diaphragm, or for it to be axially 
fastened to an operating member having a support collar of this kind. 
An operating member of this kind usually forms one of the components of the 
clutch release bearing, and this results in a certain overall complexity 
of the latter. 
It is therefore desirable to be able to have available an operating member 
which, when attached independently on the ends of the fingers of a 
diaphragm, is then adapted to be axially connected to a clutch release 
bearing in order to enable the latter to act by traction on the diaphragm. 
In French patent application filed on Mar. 24, 1972 under No. 72 11145 and 
published under No. 2.131.731, a diaphragm clutch is described, on the 
diaphragm of which an operating member of this kind is permanently 
attached in order to operate a withdrawal member, which in this particular 
case is reduced to a thrust rod serving as clutch release bearing. 
This operating member comprises on the one hand, on a first side of the 
diaphragm, a support collar applied against the diaphragm by a support 
face and on the other hand, on the other side of the diaphragm, retaining 
shoulders adapted to secure it axially to the latter. 
However, the retaining shoulders are formed thereon by the ends of 
elastically deformable tongues which, being parts separate from the 
operating member itself, are each individually attached on the latter by 
suitable fastening means. 
This results in a relatively complex arrangement, which is therefore 
expensive, while it is also possible for the retaining shoulders to become 
detached from the diaphragm fingers against which they bear, through the 
rotation about their fastening means of the elastically deformable tongues 
on which they are formed. 
In addition, although for the purposes of placing an operating member of 
this kind in position on the diaphragm to which it is to be fitted it is 
sufficient to present this member axially in front of the diaphragm in 
such a manner that the elastically deformable tongues provided on it are 
in line with the slots in the diaphragm and can thus pass axially through 
the latter, and then to turn this operating member about the axis of the 
assembly until these elastically deformable tongues are engaged on the 
fingers of the diaphragm, it is necessary in practice, because of the 
circumferential extent of the ends of these elastically deformable tongues 
forming the retaining shoulders, to widen accordingly those slots in the 
diaphragm in which they are to be engaged. 
The consequence is that the fingers of the diaphragm do not all have the 
same configuration at their ends, and that therefore they do not all work 
under the same conditions, which is prejudicial to the whole arrangement. 
In French Pat. No. 1595078 of the Dec. 13, 1968 a clutch diaphragm equipped 
with an operating member is described. 
Although in this French patent the operating member has the advantage of 
being in one piece, the retaining shoulders provided on it being integral 
with its support collar, the entire member, comprising the support collar 
and the retaining shoulders, extends on the same side of the diaphragm, so 
that those fingers of the diaphragm which are in engagement with the 
retaining shoulders are permanently bent. 
The placing in position of an operating member of this kind in fact makes 
it necessary, after the diaphragm and the operating member have been 
brought sufficiently close to one another, for the ends of as many 
diaphragm fingers as there are retaining shoulders on the operating member 
to be bent relative to the others in the axial direction, and then for the 
operating member to be turned circumferentially about the axis of the 
assembly, relative to the diaphragm, while at the end of this rotation 
those diaphragm fingers which have been engaged with the retaining 
shoulders of the operating member are prevented by the latter from 
returning to their original natural configuration. 
Apart from the fact that in the zone in which these fingers merge into the 
peripheral diaphragm portion forming the conical spring plate this results 
in an inopportune modification of the distribution of stresses in the 
peripheral portion, the operating conditions of which are liable to be 
disturbed thereby, these fingers are prevented from suitably participating 
in the axial clutch release force which has to be transmitted when the 
clutch is disengaged, to the detriment of the efficiency of the whole 
arrangement. 
Moreover, because the retaining shoulders are disposed at the bottom of 
cutouts leading out onto the support force of the support collar for 
penetration into the said cutouts of those fingers of the diaphragm which 
are to cooperate with the said retaining shoulders, the said support force 
of the support collar is discontinuous to the detriment of the rigidity of 
the latter and the extent of its surface of contact with the diaphragm, 
and the axial dimensions of the whole arrangement are relatively large. 
The general object of the present invention is an arrangement which enables 
these aforesaid disadvantages to be avoided. 
SUMMARY 
More particularly, the invention provides in one aspect, an operating 
member which is to be attached to the ends of the fingers of the diaphragm 
of a clutch, of the type comprising a one-piece annular collar, referred 
to as a support collar, which extends substantially radially and which by 
one of its faces, referred to as the support face, is intended to come to 
bear against the ends of the fingers of the diaphragm to which it is to be 
fitted, and further comprising at least two retaining collars which are 
adapted to secure it axially to the diaphragm, this operating member being 
characterised in that the retaining shoulders are turned axially in the 
direction of the support face of the support collar. 
Thus the operating member according to the invention is in combination, on 
the one hand, composed of a single piece, so that its manufacture is 
advantageously and economically simplified, and on the other hand, because 
of its support collar and its retaining shoulders, is adapted to frame 
axially, by itself, the diaphragm to which it is to be fitted, the support 
collar being disposed on a first side of the diaphragm and the retaining 
shoulders on the other side of the latter, so that none of the fingers of 
the diaphragm is subjected to any definitive bending. 
In practice, each of the retaining shoulders provided on the operating 
member according to the invention is formed on a retaining finger which 
extends substantially circumferentially at the end of a support leg 
generally parallel to the associated support collar. 
Likewise in practice, the support leg extends from the support collar. For 
example, it may extend from the outer periphery of the support collar. 
As an alternative, it may extend from the inner periphery of the support 
collar, even when the corresponding operating member comprises a sleeve 
which is generally axial, starting from the said inner periphery, over at 
least a part of its path and the support leg is then axially integral with 
the axial sleeve, being circumferentially continuous with the latter. 
In all cases, the support force of the support collar, that is to say the 
force by which this collar bears against the diaphragm, is always 
advantageously continuous, which is favourable both for the rigidity of 
the support collar and for the extent of its surface of contact with the 
diaphragm, and therefore for a reduction of wear on this contact surface. 
Likewise in all cases, the operating member according to the invention 
simply requires, for it to be placed in position, that the diaphragm and 
the operating member should be brought close to one another, that certain 
of the fingers of the diaphragm should be temporarily bent, and that the 
operating member should be turned relative to the diaphragm, without 
definitive bending of the respective diaphragm fingers by the retaining 
shoulders of the operating member. 
In this respect the present invention has another aspect, comprising a 
process for the placing in position, on the ends of the fingers of the 
diaphragm of a clutch, of a one-piece operating member comprising an 
annular collar, referred to as the support collar, which extends 
substantially radially and which by one of its faces, referred to as the 
support face, is intended to bear against the ends of the fingers of the 
diaphragm which is to be equipped with it, on a first side of the 
diaphragm, and, on the other side of the diaphragm, at least two retaining 
shoulders which are adapted to secure it axially on the diaphragm, this 
process being of the type in which, after the diaphragm and the operating 
member have been brought sufficiently close to one another, the ends of as 
many diaphragm fingers as there are retaining shoulders on the operating 
member are bent relative to the others in the axial direction, then the 
operating member is turned circumferentially about the axis of the 
assembly, relative to the diaphragm, and this process being characterised 
in that, the operating member having in accordance with the invention 
retaining shoulders formed on retaining fingers extending 
circumferentially at the end of support legs adapted to pass axially 
through the diaphragm, the previously bent fingers of the diaphragm are 
then allowed to return to their original configuration. 
The present invention has as a further object a unitary assembly for a 
clutch, of the kind formed on the one hand by a diaphragm and on the other 
hand of an annular member, known as the operating member, attached to the 
ends of the fingers of the said diaphragm, this unitary assembly being 
characterised in that the operating member is in one piece according to 
the invention, as briefly described above. 
In practice, a unitary assembly of this kind is very particularly 
characterised in that, the retaining shoulders formed on the operating 
member being formed on retaining fingers which extend circumferentially at 
the end of support legs, these support legs pass axially through the 
diaphragm with the aid of slots existing between the fingers of the 
latter, or else by way of its axial cavity. 
In all cases, the diaphragm in a unitary assembly of this kind has, at 
rest, a configuration identical to that which it would have if it were not 
provided with an operating member. 
In addition, the ends of these radial fingers all have the same contour. 
The engagement on the diaphragm of the operating member according to the 
invention in fact has the advantage of not requiring any particular 
cutting out for certain of the fingers of the diaphragm, since this 
engagement needs only the slots separating pairs of these fingers or else 
the axial cavity surrounded by them.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
FIGS. 1 to 9 illustrate the application of the invention to a pulled clutch 
release bearing 10, that is to say a clutch release bearing intended to 
act by traction on the diaphragm 11 of the clutch which it is to control. 
For the purpose of acting on the diaphragm 11 this clutch release bearing 
10 is itself subjected, by any suitable control means (not illustrated), 
to traction which as shown by the arrow F1 in FIG. 1 urges it in the 
opposite direction to the diaphragm 11. 
Since a clutch release bearing of this kind does not in itself form part of 
the present invention, it has only been indicated schematically in FIG. 1 
and will not be described in further detail. 
In a manner known per se, the diaphragm 11 which the clutch release bearing 
has to control is a generally annular part comprising, in the form of a 
single piece, a circularly continuous peripheral portion 12, which is 
adapted to form a conical plate spring and a central portion 13 which is 
split up into radial fingers 15, around an axial cavity 14, by radial 
slots 16, each of which starts individually from a passage 17 of larger 
section situated at the root of the radial fingers 15, between the 
peripheral portion 12 and the central portion 13 (FIGS. 1 and 6). 
These arrangements are well known per se and, since they do not form part 
of the present invention, they will not here be described in greater 
detail. 
Likewise in a manner known per se, in order to enable the clutch release 
bearing 10 to act on the diaphragm 11 there is associated with the latter 
a member 19, which here for the sake of convenience is called an operating 
member, and which likewise constitutes an annular part and is adapted to 
be attached to the ends of the radial fingers 15 of the diaphragm 11. 
The operating member 19 comprises generally an annular collar 20, which for 
the sake of convenience is referred to as a support collar, and which 
extends substantially radially. One face 22 of the support collar, 
referred to as the support face, is adapted to come to bear against the 
ends of the radial fingers 15 of the diaphragm 11, on the opposite side of 
the latter to that where the clutch release bearing 10 is disposed, and 
the support collar further comprises at least two shoulders 23, which are 
adapted to secure it axially to the diaphragm 11. 
According to the invention, the operating member 19, which is shown by 
itself if FIGS. 2 to 4, is in one piece and the retaining shoulders 23 
with which it is provided are turned axially in the direction of the 
support face 22 of the support collar 20, so that they can cooperate with 
that face of the diaphragm 11 which faces the clutch release bearing 10. 
In practice, three retaining shoulders 23 are provided, regularly 
distributed circularly around the axis of the assembly, and each of them 
is formed on a retaining finger 25 which extends substantially 
circumferentially at the end of a support leg 26, generally in a direction 
parallel to the support collar 20. 
In practice, each support leg 26 extends from the support collar 20 and, 
more precisely, in this embodiment, from the outer periphery of this 
support collar 20, being integral with the latter. 
In succession from the support collar 20 to the corresponding retaining 
finger 25, the support leg 26 comprises a first portion 28 which extends 
substantially radially, a second portion 29 which, in the plane of the 
first portion 28, extends substantially circumferentially, and a third 
portion 30 which extends generally axially and substantially at right 
angles to the plane of the previously mentioned portions 28 and 29, being 
joined at right angles both to the portion 29, which it follows, and to 
the respective retaining finger 25. 
Likewise in practice, the circumferential length of a retaining finger 25 
is preferably less than the sum of the width of a finger 15 of the 
diaphragm 11 and that of a slot 16 in the diaphragm, both measurements 
being taken on the circumference along which the respective retaining 
finger 25 extends, it being obvious that the shorter the circumferential 
length of the latter, the greater its rigidity will be. 
In order to be adapted to act on the diaphragm 11, the support collar 20 is 
provided annularly, on its support face 22 and in the direction of the 
retaining shoulders 23, with a rounded boss 32 which in practice, in the 
embodiment illustrated, is formed by a dished portion of the said support 
collar 20 and which is advantageously circumferentially continuous. 
Finally, in the embodiment illustrated, the operating member 19 being 
intended to cooperate with a clutch release bearing acting by traction, 
comprises, starting from the inner periphery of its support collar 20 and 
integral with the latter, a generally axial sleeve 33 which extends on the 
side on which the retaining shoulders 23 are disposed and projects 
substantially beyond the latter. 
As will be noted, the retaining shoulders 23 are radially spaced apart from 
this axial sleeve 33, being externally distant from the latter by a radial 
dimension at least equal to the radial width of the support collar 20. 
The operating member according to the invention can easily be produced, for 
example by cutting out and pressing the member in a suitable manner from a 
metal blank. 
For preference, and as illustrated, the fold lines 35 delimiting the third 
portion 30 of its support legs 26 extend substantially radially, so that 
circumferentially a third portion of this kind has a slight thickness, of 
the order of that of the original blank, and in any case less than the 
circumferential width of a slot 16 in the diaphragm 11. 
The operating member 19 according to the invention can be placed in 
position on the diaphragm 11 in the following manner, for example: after 
the diaphragm 11 and the operating member 19 have been brought 
sufficiently close axially to one another to bring the axial sleeve 33 of 
the operating member 19 into axial engagement in the axial cavity 14 of 
the diaphragm 11, in the direction of the arrow F2 in FIG. 5, the ends of 
as many radial fingers 15 of the diaphragm 11 as there are retaining 
shoulders 23 on the operating member, in this particular case three, are 
bent axially in relation to the other fingers, in the direction of the 
arrow F3 in FIG. 5, and then circumferentially in the direction of the 
arrow F4 in FIG. 6, and when three fingers of the diaphragm 11 have been 
bent in this manner the operating member 19 is rotated about the axis of 
the assembly relative to the diaphragm 11. 
At the end of this relative rotation of the operating member 19, the 
retaining fingers 25 formed on the latter straddle those radial fingers 15 
of the diaphragm which had previously been bent (FIG. 8), on the opposite 
side of these radial fingers to that where the associated support collar 
20 is disposed. 
It is then sufficient to allow the previously bent radial fingers 15 of the 
diaphragm 11 to return to their original configuration (FIG. 7). 
The operating member 19 according to the invention is then in fact suitably 
fastened to the diaphragm 11, the latter being gripped axially, in 
practice with play, between, on the one hand, on a first side, the support 
collar 20 of the operating member 19 and, on the other hand, on the 
opposite side, the retaining fingers 25 of the operating member 19, the 
support legs 26 of these retaining fingers 25 passing axially through the 
diaphragm 11 by their third portion 30, which passes through the slots 16 
formed in the diaphragm 11. 
In the unitary assembly thus composed of a diaphragm 11 and an operating 
member 19 attached to it, the diaphragm 11 is entirely in the 
configuration which was its actual original configuration, and it did not 
have to undergo any special cutting or permanent deformation for the 
attachment of the operating member 19. 
It therefore fully retains its inherent mechanical characteristics without 
any modification, and each of the fingers 15 is in contact with the 
rounded boss 22 formed on the support collar 20 of the operating member 
19, which is favourable to the minimisation of wear. 
The unitary assembly formed by the diaphragm 11 and the operating member 19 
can advantageously be handled as a unit, particularly for the assembly of 
the clutch mechanism and the equipment for which it is intended. 
It is then sufficient to fasten the corresponding clutch release bearing 10 
axially to it. 
Since the manner in which this fastening is done does not form part of the 
present invention, it will not be described here. 
According to the alternative method illustrated in FIG. 9, the rigidity of 
the support legs 26 of the retaining fingers 25, and more precisely that 
of their axial portion 30, is utilised in order to effect by means of 
these legs the bending of the fingers 15 of the diaphragm 11 which adjoin 
those on which the retainint fingers 25 are to be engaged. 
FIG. 10 illustrates the application of the invention to the case where the 
clutch release bearing 10 is intended to act by thrust on the diaphragm 
11, that is to say the case in which in order to act on the diaphragm 11 
the associated control means urges it in the direction of the diaphragm 
11, as shown by the arrow F5 in FIG. 10. 
In such cases the operating member is not provided with an axial sleeve and 
its support collar 20 is extended radially, in the direction of the axis 
of the assembly, to a sufficient extent to form a support ring 37 suitable 
for the action of the clutch release bearing 10. 
While, as previously, the collar 20 is provided with a circumferentially 
continuous rounded boss 32 for the purpose of acting on the diaphragm 11, 
a support ring 37 of this kind can advantageously provide a plane support 
surface for the clutch release bearing 10, so that the latter can also 
have for that purpose an advantageously plane operating or engagement 
surface. 
Otherwise, the mode of construction and method of attachment are identical 
to those described above. 
The axial compactness of this embodiment will be appreciated. In the 
embodiments described above, the support legs 26 of the retaining fingers 
25 extend from the outer periphery of the support collar 20. 
As an alternative, they may extend from the inner periphery of the support 
collar 20. 
This possibility is illustrated in FIGS. 11 and 12, which relate, by way of 
example, to the case in which the associated clutch release bearing is a 
pulled clutch release bearing (not shown in the drawings). 
In the embodiment illustrated each support leg 26 comprises in succession, 
from the support collar 20 to the corresponding retaining finger 25, a 
first portion 38 which extends substantially axially and a second portion 
39 which extends substantially radially. 
In cases where, as illustrated, the operating member 19 has an axial sleeve 
33 extending from the inner periphery of its support collar 20 while the 
associated clutch release bearing 10 is a pulled release bearing, the 
axial portion 38 of each support leg 26 may obviously be laterally 
integral with such an axial sleeve 33 over at least part of its extent, 
being circumferentially continuous with the said sleeve, as illustrated. 
In the embodiment illustrated, the axial sleeve 33 has in practice only a 
short axial length and it has the general shape of a venturi, having two 
generally frustoconical portions, one on each side of a central neck of 
smaller diameter. The retaining shoulders 23 formed on the operating 
member 19 in this embodiment, as in previously described embodiments, are 
still radially at a distance from its axial sleeve 33. 
The manner in which this form of construction of the operating member 19 is 
positioned on the diaphragm 11 to which it is to be fitted is idential to 
that previously described. 
However, as will be noted, in this embodiment the support legs 26 of the 
retaining fingers 25, and therefore also of the retaining shoulders 23, 
pass axially through the diaphragm 11, not by way of the slots 16 in the 
latter, but by way of its axial cavity 14. 
Consequently, since this embodiment has no part inserted into the diaphragm 
slots, it is advantageously capable of having greater transverse play in 
relation to the diaphragm, at right angles to the axis of the assembly, 
and this is favourable to the self-centering of the associated clutch 
release bearing when the latter is of the self-centering type. 
In addition, during its manufacture there is minimum wastage, since the 
support legs formed on it can be formed from the inevitable central waste 
portion corresponding to its axial cavity. 
The present invention is not limited to the embodiments described and 
illustrated, but includes all variants of construction and/or of 
combinations of their various elements.