Clutch release bearing, in particular for automotive vehicle

A clutch release bearing comprises a drive member through which it is adapted to operate on the clutch release device of a clutch. It also comprises an operating member through which it is adapted to be operated on by a clutch release yoke. The operating member incorporates two recesses the bottom of each of which faces axially towards the drive member and forms a transverse bearing facet. Each of the recesses is adapted to interlock with the clutch release yoke to prevent rotation of the clutch release bearing about its axis.

BACKGROUND OF THE INVENTION 
1. Field of the invention 
The present invention is generally concerned with clutch release bearings, 
in particular those for automotive vehicles. 
2. Description of the Prior Art 
As is known, a clutch release bearing generally comprises an operating 
member through the intermediary of which it is adapted to be operated on 
by a control member, in practice a clutch release yoke, and a drive member 
which is coupled to said operating member by a cover, for example, and 
through the intermediary of which the clutch release bearing is adapted to 
operate on the clutch release device of a clutch. 
The present invention is more particularly, but not necessarily 
exclusively, concerned with self-centering clutch release bearings, that 
is to say clutch release bearings in which the drive member is able to 
move relative to the operating member perpendicularly to the axis of the 
assembly wherein self-centering results. 
One problem to be overcome in producing clutch release bearings of this 
type results from the fact that, because their drive member is then in 
contact with a rotating member, namely the clutch release device of the 
clutch concerned, they are subjected in service to forces tending to 
rotate them about their axis. 
Any such rotation of the clutch release bearing about its axis in service 
could not fail to disturb the self-centering action, especially when the 
self-centering action is "maintained", that is to say when springloaded 
friction means are provided between the drive member and the operating 
member. 
Thus it is desirable or even essential to prevent the clutch release 
bearing rotating about its axis in service. 
To achieve this it has been proposed to key the clutch release bearing 
circumferentially to the clutch release yoke which is of course keyed 
against rotation about the axis of the clutch release bearing by virtue of 
its being pivotally mounted on the casing of the associated gearbox; when 
the clutch release bearing comprises a cover with which the clutch release 
yoke cooperates, it has been proposed to key the operating member 
circumferentially to the cover. 
Concerning the circumferential keying of the clutch release bearing to the 
clutch release yoke, as the clutch release yoke in practice comprises two 
fingers through the intermediary of which it is engaged over a clutch 
release bearing of this kind so as to operate thereon, it has been 
proposed to employ two axial facets on the clutch release bearing, usually 
called axial guide facets, extending axially and parallel to each other 
and therefore adapted to cooperate with respective lateral surfaces of 
said fingers of the clutch release yoke, these surfaces facing each other. 
Axial guide facets like these are not always easy to provide, especially 
where they must be formed on a cover. 
Furthermore, they may themselves give rise to difficulties in certain types 
of clutch release bearing, more precisely "pull-type" clutch release 
bearings, that is to say clutch release bearings designed to operate in 
traction on the clutch release device of the clutch to be controled. 
Such traction operation implies, on the one hand, that the drive member of 
the clutch release bearing is engaged behind the clutch release device of 
the clutch to be controled, or is engaged with some form of member, a 
coupling member, for example, itself engaged behind the clutch release 
device, and, on the other hand, that the clutch release yoke be engaged 
transversely between the clutch release device and transverse bearing 
facets provided for this purpose on the clutch release bearing. 
In practice the clutch release yoke and the clutch release bearing form 
parts of two different assemblies, on the one hand that comprising the 
casing of the gearbox, which carries the clutch release yoke, and on the 
other hand that comprising the engine block, which usually carries the 
associated clutch and therefore the clutch release bearing. 
At assembly time, that is to say when these two assemblies are brought 
axially towards each other, it is necessary to engage progressively the 
fingers of the clutch release yoke behind the transverse bearing facets of 
the clutch release bearing. However, demounting or disconnection of the 
two assemblies from each other must be possible for subsequent access to 
the clutch for changing or overhauling it, for example. 
It must then be possible to disengage the clutch release yoke from the 
clutch release bearing. 
The pivoting of the clutch release yoke required to engage it behind the 
transverse bearing facets of the clutch release bearing at assembly time 
or to disengage it therefrom at demounting time is not always possible, 
since it requires a non-negligible dead space which is not always 
available. 
To eliminate such pivoting movements it has been proposed to provide 
between the clutch release bearing and the clutch release yoke a 
quarter-turn coupling whereby the clutch release bearing is turned about 
its axis through an angle sufficient for the transverse bearing facets to 
escape from the fingers of the clutch release yoke at demounting time, for 
example, so that they can then be disengaged axially relative thereto. 
It is clear that when axial guide facets for the fingers of the clutch 
release yoke are provided on the clutch release bearing, these axial guide 
facets oppose rotation of the clutch release bearing about its axis. 
Turning now to the circumferential keying of the operating member of the 
clutch release bearing to the cover, where it comprises a cover, it has 
been proposed, in particular in U.S. Pat. No. 4 529 075 and in a French 
patent of addition application filed 15 June 1983 under the number 83 
09874 and published under the number 2 533 281 relating to a parent French 
patent filed 18 June 1981 under the number 81 12001 and published under 
the number 2 508 125, to exploit elastically deformable lugs (provided for 
coupling together the cover and the operating member) to procure such 
circumferential keying. 
In practice these elastically deformable lugs form part of the operating 
member and cooperate with two openings provided for this purpose in the 
cover, the part cooperating with an opening being complementary thereto in 
the circumferential direction. 
Although giving satisfaction, an arrangement of this kind has the 
disadvantage of applying non-negligible circumferential loads to the 
elastically deformable lugs in service. 
For them to be able to withstand such loads, they must be made sufficiently 
thick, which is detrimental to their elasticity. 
A general object of the present invention consists in arrangements which, 
while procuring in a satisfactory way the necessary circumferential 
retention of the clutch release bearing, make it possible to eliminate the 
disadvantages outlined hereinabove, conferring also other advantages. 
SUMMARY OF THE INVENTION 
The present invention provides a clutch release bearing comprising a drive 
member through the intermediary of which it is adapted to operate on the 
clutch release device of a clutch and an operating member having two 
recesses the bottom of each of which faces axially towards said drive 
member and forms a transverse bearing facet through the intermediary of 
which said clutch release bearing is adapted to be operated on by a clutch 
release yoke, wherein each of said recesses is adapted to interlock with 
said clutch release yoke to prevent rotation of said clutch release 
bearing about its axis. 
Thus any rotation of the clutch release bearing relative to the clutch 
release yoke in service is impossible, without it being necessary to 
provide for this purpose any guide facets on the clutch release bearing. 
For both directions of rotation the clutch release bearing comes into 
circumferential bearing engagement with the clutch release yoke, through 
the intermediary of one or other edges of the recesses whose bottoms form 
the transverse bearing facets. 
Where a quarter-turn type coupling must be provided for the reasons stated 
hereinabove between the clutch release bearing and the clutch release 
yoke, the transverse bearing facets may in the usual way form part of 
radial lugs provided for this purpose on the clutch release bearing. 
At demounting time it is then only necessary to pivot the clutch release 
yoke slightly to disengage it from the recesses provided in accordance 
with the invention on the clutch release bearing and so permit rotation of 
the clutch release bearing about its axis, as is necessary at this time. 
However, when the necessary volume is available and it is possible to apply 
at assembly and demounting time significant pivoting movement to the 
clutch release yoke, the two transverse bearing facets of the clutch 
release bearing are, in accordance with another feature of the invention, 
advantageously linked to each other by a circumferentially continuous 
flange, the recesses of which they form the bottom resulting, for example, 
from simple local depression of the flange. 
With an arrangement of this kind blind assembly is advantageously possible: 
once the clutch release yoke is engaged transversely behind the flange 
that the clutch release bearing thus features, it is sufficient to rotate 
the latter about its axis until the recesses formed locally in the flange 
come into face-to-face relationship with the ends or pads of the fingers 
of the clutch release yoke and these engage in them to provide the 
necessary circumferential interlock. 
If required, elastic means may be provided to urge the clutch release yoke 
continuously towards the transverse bearing facets of the clutch release 
bearing. 
For example, these elastic means are preferably carried permanently by the 
clutch release bearing. 
Also, when a cover is provided for coupling the drive member axially to the 
operating member, with means for preventing rotation of the operating 
member on the cover, the rotation preventing means preferably comprise a 
projection carried by the operating member adapted to interlock with a 
local deformation in the cover. 
Thus when elastically deformable lugs are provided between the operating 
member and the cover, they may be relieved of the rotational blocking 
function so that, by making their ends thinner, they may advantageously be 
made more flexible, if required. 
Also, circumferential play may advantageously be provided between the 
portion of the elastically deformable lugs cooperating with an opening in 
the cover and the opening, so as to protect them from deterioration in 
service. 
For example, when, as is usually the case, the operating member features a 
transverse flange, the projection provided in accordance with the 
invention on the operating member may simply consist of a peg radially 
extending said flange. 
This peg is preferably itself extended axially, specifically and 
advantageously to stiffen it. 
The end of this axial extension of the peg is preferably beveled and, the 
cover comprising a circumferentially continuous annular side wall, the 
deformation that the cover features in accordance with the invention for 
cooperation with the corresponding projection on the operating member is 
preferably a V-shaped deformation in the annular wall. 
As a result, the relative axial engagement of the cover over the operating 
member required at assembly time is advantageously facilitated and 
simplified, the projection on the operating member constituting with the 
deformation in the cover means for registering these members and the 
beveled axial extension of this projection itself procuring, through 
cooperation with the V-shaped configuration of the deformation in the 
cover, significant guidance during such axial engagement. 
Finally, the summit of the V-shaped deformation thus provided locally in 
the annular wall of the cover is preferably situated generally in line 
with the median area of one of the recesses the bottom of which 
constitutes one of the transverse bearing facets of the assembly. 
The clutch release device in accordance with the invention thus 
advantageously has a plane of symmetry so that the circumferential 
direction in which the rotational loads to which it it subject in service 
tend to cause it to rotate about its axis is immaterial. 
The characteristics and advantages of the invention will emerge from the 
following description given by way of example with reference to the 
accompanying diagrammatic drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
As shown in the figures, the clutch release bearing 10 is represented in 
full line whereas the members with which it is intended to cooperate are 
schematically represented in chain-dotted line, in particular the guide 
member 11. The clutch release bearing 10 in accordance with the invention 
generally comprises a drive member 12 through the intermediary of which it 
is adapted to operate on the clutch release 13 of the clutch and an 
operating member 14 through the intermediary of which it is adapted to be 
operated on by a control member 15. 
The operating member 14 comprises an axial sleeve 21 through the 
intermediary of which the clutch release bearing 10 is adapted to be 
slidably engaged on any form of guide support, for example the flared 
guide tube usually surrounding the input shaft of the associated gearbox. 
The clutch release device 13 is shown only in part in FIGS. 2 and 3. It may 
consist, for example, of the ends of radial fingers of a diaphragm. 
Likewise, the control member 15 is only partially represented in FIG. 1. In 
practice it comprises a control yoke the fingers 16 of which are engaged 
transversely over the clutch release bearing 10 at two diametrally 
opposite points. 
For example and as shown here, the clutch release yoke is mounted on the 
casing of the gearbox to rotate about an axis at right angles to the axis 
of the guide member 11. For the purpose of its operation on the clutch 
release bearing 10, the clutch release yoke 15 comprises two fingers 16 by 
means of which it embraces the clutch release bearing 10 and the ends of 
which are shaped so as to be able to operate on the latter. 
Consisting in practice of a clutch release bearing designed to operate in 
traction on the clutch release device 13, the clutch release bearing 10 in 
accordance with the invention has a drive member 12 that comprises a 
sleeve 17 which has a transverse coupling member 19 at one end carried 
permanently by the clutch release device 13 and to which the clutch 
release bearing 10 is attached snap-fastener fashion through its drive 
member 12 at assembly time with an elastically deformable ring 20 provided 
for this purpose between the coupling member 19 and the drive member 12. 
The operating member 14 comprises a transverse flange 22 attached to the 
sleeve 21 itself extended by an axial rim 26. 
In practice the sleeve 21 and the flange 22 are in one piece, the 
combination being obtained, for example, by molding any appropriate 
synthetic material. 
The drive member 12 is mainly accommodated within the internal volume 
defined by the operating member 14, between the sleeve 21 and the axial 
rim 26; in the embodiment shown it is formed by a ball bearing 25 the 
outer race 24 of which, acted on by an axially acting spring washer 27 
bearing against the annular flange 22 of the operating member 14, presses 
through its opposite edge on the bent over edge 28 of the cover 29; its 
internal race 30 is adapted by means of a retaining groove 30a to 
cooperate with the elastic ring 20, the internal race 30 projecting 
axially for this purpose outside the cover 29, by means of the central 
opening in the bent over edge 28 of the latter. 
In practice the elastic ring 20 is adapted to cooperate with a drive 
bearing surface forming part of the coupling member 19. 
The drive bearing surface/retaining groove arrangement is well known in 
itself, for example from French patent application No. 83 06847 filed 28 
Apr. 1983 and published under the number 2 545 172 and U.S. patent 
application Ser. No. 603 287 filed 24/04/84 now U.S. Pat. No. 4,588,061 
which is incorporated herein by reference. 
For securing the assembly the drive member 12 is coupled axially to the 
operating member 14 by the cover 29. For descriptive purposes, the 
combination of the operating member 14 and the cover 29 will be considered 
to be operating means. 
The cover 29 comprises an annular side wall 31 extending axially. This 
annular wall 31 couples the cover 29 to the flange 22 of the operating 
member 14. 
For example, and as shown here, clipping means with elastically deformable 
lugs 32 and openings 33 are provided to this end between the annular wall 
31 of the cover 29 and the flange 22 of the operating member 14. 
These elastically deformable lugs 22, of which there are three, regularly 
spaced in the circumferential direction, for example, are part of the 
operating member 14 and the corresponding openings 33 are part of the 
cover 29. 
In practice the elastically deformable lugs 32 project axially from the 
flange 22 of the operating member 14, locally interrupting the ring formed 
by the axial rim 26 of the flange 22, and feature a bead 35 projecting 
radially outwards to cooperate with the corresponding opening 33. 
In the circumferential direction the bead 35 is complementary to the 
opening 33. 
Axial play is preferably provided between the bead 35 of an elastically 
deformable lug 32 and the corresponding opening 33 in the cover 29. 
As this is a maintained self-centering clutch release bearing, the drive 
member 12 is able to move in any radial direction relative to the 
operating member 14 within the limits of a predetermined annular clearance 
provided for this purpose between the ball bearing 25 of the drive member 
12 and the ring 26 of the operating member 14. 
The clutch release bearing 10 in accordance with the invention comprises, 
at diametrally opposed positions, two transverse bearing facets 36 for the 
clutch release yoke 15 to operate on which extend generally radially to 
co-operate with the ends of the fingers 16 of the clutch release yoke 15. 
These transverse bearing facets 36 each form part of a lug 37 which is in 
one piece with the cover 29, extending transversely in substantially the 
same plane as the annular flange 22 of the operating member 14. 
It is thus through the intermediary of the cover 29 that the operating 
member 14 is in this case adapted to be operated on by the clutch release 
yoke 15. 
Each of the lugs 37 that the cover 29 thus comprises has its main part 
slightly offset axially in the direction opposite that of the bent over 
edge 28 relative to its lateral edges which are substantially in line with 
the end concerned of the cover 29. 
It thus features a recess forming a concavity facing axially towards the 
drive member 12 of the release bearing. 
Displacement of the yoke in the direction opposite to its bearing direction 
over a distance equal to the depth of this recess is then sufficient to 
secure rotational releasing of the release bearing and so to permit 
decoupling thereof from the clutch release device of the clutch. 
A leaf spring 39 is disposed substantially circumferentially around the 
clutch release bearing 10 that carries it and comprises, in succession, a 
first section 40 by which it is attached to the clutch release bearing 10, 
a second section 41 by which it extends generally tangentially to the 
annular wall 31 of the cover 29, and a third section 42 forming its free 
end. 
By means of its first section 40 the leaf spring 39 is attached by a rivet 
44 to a radial lug 43 of the clutch release bearing 10. The radial lug 43 
is in one piece with the cover 31 of the clutch release bearing 10 and 
continuous with the lug 37 of the latter on which is formed the transverse 
bearing facet 36 concerned. 
In the embodiment shown the second section 41 of the leaf spring 39 is 
generally S-shaped as seen from the side (FIG. 2) in order to bear on a 
transverse side of a finger 16 of the clutch release yoke 15. 
At assembly time the clutch release bearing 10 is placed on its guide 11 
which is carried by the casing of the gearbox and the fingers 16 of the 
clutch release yoke 15 are engaged with it, each of the fingers 16 being 
inserted into the recess formed on the corresponding bearing facet 36, one 
of them also being engaged under the median section 41 of the leaf spring 
39. 
The assembly which comprises the gearbox equipped in this way with the 
clutch release bearing 10 and the clutch release yoke 15 is brought 
towards the engine block carrying the clutch to be controled. To couple 
the clutch release bearing 10 to the clutch release device 13 of the 
clutch, it is sufficient to move the clutch release bearing 10 axially 
towards the clutch release device 13 and pivot the clutch release yoke 15 
about its axis in the direction of the arrow F1 in FIG. 2. 
Operating on tangs 45 provided for this purpose on the cover 29 of the 
clutch release bearing 10, the clutch release yoke 15 then secures 
snap-fastener type engagement of the drive member 12 of the clutch release 
member 10 onto the coupling member 19 carried by the clutch release device 
13. 
The bearing facets 36 with their recesses, one of these facets being 
associated with leaf spring 41, constitute retaining means adapted to 
oppose any rotation of the clutch release bearing 10 about its axis in 
service. 
The return spring means constituted by this spring could equally well be 
disposed at another location whilst still retaining the role of 
continuously urging the control member 15 towards the transverse bearing 
facet. 
The embodiment of FIGS. 5 through 8 illustrates two other features of the 
invention. 
Unlike the preceding embodiment, the coupling member 19 is no longer 
carried permanently by the clutch release device 13, but bears axially on 
the ring 30 via the ring 20, a Belleville washer 52 bearing against a 
shoulder of said ring 30 so as to clamp the clutch release device between 
the washer 52 and the coupling member 13. 
According to one feature of this embodiment, the cover 29' differs from the 
cover 29 of the previous embodiment in that it features at its periphery a 
continuous flange 46, two depressions 47 and 48 at diametrally opposite 
locations on the flange replacing the bearing facets 36 formed on the lugs 
37 of FIGS. 1 through 4. 
An embodiment of this kind gives the cover a more favorable structure from 
the mechanical and manufacturing points of view because of the continuous 
nature of the peripheral rim formed by the flange 46. However, because of 
this continuity there is lost the possibility of the release bearing 
escaping axially between the fingers of the yoke on limited pivoting of 
the yoke 15: at assembly and demounting time it is in this case necessary 
to provide sufficient volume for enough pivoting to occur to release the 
flange as a whole. 
However, provided that this condition can be met, there is obtained the 
advantageous possibility of blind assembly: once the yoke is engaged 
behind the flange 46, it is sufficient to turn the latter about its axis 
until the ends of the fingers 16 are disposed in the localized depressions 
47 and 48, so that the release bearing is then keyed circumferentially. 
According to another feature of this embodiment the means for preventing 
rotation of the cover 29' relative to the operating member 14' are 
improved: the flange 22' of the operating member 14' has a peg-shaped 
peripheral projection 49 with an axial extension 50 merging through a 
bevel with a free edge of the axial rim 26'. 
The skirt 31' of the cover features a generally V-shaped deformation 51 
adapted to cooperate with the aforementioned peg. By virtue of the 
resulting circumferential keying between the cover 29' and the operating 
member 14 the elastically deformable lugs 32 are relieved of this 
circumferential keying function and serve only to axially couple the cover 
and the operating member. This means that the lugs 32 may be made lighter 
and that a relatively large circumferential clearance be provided between 
the end parts 35 of the lugs and the openings 33 intended to receive them, 
facilitating assembly. 
It is thus the radial projection in the form of the peg 49 which 
constitutes together with the deformation 51 in the cover the indexing 
means between these members procuring relative guidance during axial 
engagement thereof. 
As can be seen in FIG. 5, the summit of the deformation 51 is in line with 
the median area of the recess 48 whose bottom constitutes a bearing facet 
for one finger 16 of the clutch release yoke 15. The bearing area actually 
used is situated in this case between the deformation 51 and that of the 
edges of the recess which is on the upstream side relative to the 
direction of rotation indicated by the arrow F. Given that the structure 
in question has a plane of symmetry corresponding in FIG. 5 to the 
cross-section plane indicated at VI--VI, it will be understood that in the 
event of rotation in the opposite direction the effective bearing area 
will be disposed on the other side of the deformation 51. The release 
bearing is thus adapted to resist rotational loads to which it may be 
subjected because of the drag torque of the bearing, whichever direction 
of rotation of the motor it may be associated with. 
The indexing system just described with reference to FIGS. 5 through 8 is 
naturally also suitable for combination with bearing facets provided in 
accordance with FIGS. 1 through 4 on lugs projecting radially from the 
perimeter of the cover towards the release bearing. 
Moreover, it remains possible, of course, to provide two leaf springs 39 at 
diametrally opposite positions to operate simultaneously on the two 
fingers of the clutch release yoke. 
It will be understood that various changes in the details, materials and 
arrangements of parts which have been herein described and illustrated in 
order to explain the nature of the invention may be made by those skilled 
in the art within the principle and scope of the invention as expressed in 
the appended claims.