Clutch release bearing assembly

An improved self-centering bearing assembly for clutch release mechanism includes a radial bearing with a rotatable inner and non-rotatable outer race. The outer race is resiliently held for radial self-centering movement by an attachment member which mounts the bearing assembly to a plastic carrier of the clutch release mechanism. The resilient element that allows self-centering is compressed between a radial flange of the attachment and a face of the outer race. When removed from the carrier, the resilient element expands sufficiently to bias the radial flange into a radially extending portion of a declutching finger contacting member rigid to the inner race. This retains the attachment member to the bearing as a separately handled, rattle-free unit. The spacing between that portion of the contact member and the face of the outer race against which the resilient element bears is small enough not only to allow unitization, but also small enough that when the resilient element of the mounted bearing assembly is compressed, the resulting gap between that portion of the contact member and the radial flange is just sufficient to allow relative rotation of the races, so that the bearing is shielded. Therefore, the extension of the contact member has both a retention and a shielding function in cooperation with structure already present for other purposes.

This application relates to clutch release bearing assemblies and 
specifically to an improved self-centering clutch release bearing 
assembly. 
BACKGROUND OF THE INVENTION 
Clutch release mechanisms in manual transmission vehicles generally include 
a carrier that is moved axially toward and away from a plurality of 
declutching fingers of a diaphragm-type clutch. A control means, such as a 
fork or hydraulic cylinder, moves the carrier. A bearing device is 
necessary between the carrier and the declutching fingers to mate the 
axial motion of the carrier to the rotary motion of the declutching 
fingers. 
While a conventional thrust bearing has been used in the past in such a 
clutch release mechanism, the trend today is toward the use of a radial 
bearing having inner and outer races with a complement of bearing balls 
therebetween. It is also desirable that a means for allowing the bearing 
to self-center relative to the clutch be provided, since the carrier 
itself may not always be coaxial with the clutch. One conventional and 
simple self-centering means may be seen in the U.S. patent to Maurice, 
U.S. Pat. No. 3,416,637. A resilient element, such as a Belleville washer, 
is compressed against a face of one of the races of the bearing to bias 
the other face of the race into a radial wall of the carrier and hold the 
race non-rotatably, but radially slidable, relative to the carrier. The 
other race of the bearing is free to rotate and has a contact member that 
is engageable with the declutching fingers as the carrier moves. The 
radial sliding provided by the compressed resilient element allows the 
bearing to move to a centered position relative to the clutch. One means 
of compressing the resilient element is an attachment member that is 
detachably joinable to the carrier so as to axially compress the resilient 
element between the bearing face and a radial flange of the attachment 
member. This also mounts the bearing to the carrier. 
An example of a clutch release bearing assembly of the type referred to 
above may be seen in the UK patent application No. GB 2073353A. There, the 
clutch release bearing assembly includes a radial bearing in which the 
outer race is held to the carrier by an attachment member that snap fits 
with the carrier to axially compress a resilient washer between a radial 
flange of the attachment member and a face of the outer race. The inner 
race is engageable with the declutching fingers. However, the attachment 
member is separate from the bearing and must be separately handled when 
the bearing is mounted to the carrier. A similar design is found in the 
U.S. patent to Beccaris, U.S. Pat. No. 4,403,685. Not only is the 
attachment member a separately handled piece, but an additional cover 
member is necessary to fill the gap between the inner and outer races to 
shield the rolling elements of the bearing. 
SUMMARY OF THE INVENTION 
The subject invention provides an improved self-centering bearing assembly 
for a clutch release mechanism in which a retention and shielding portion 
of the contact member cooperates with the resilient element to retain the 
attachment member to the bearing as a substantially rattle-free unit when 
the housing is detached from the carrier. The retention and shielding 
portion also cooperates with the attachment member to shield the bearing 
when the bearing is mounted to the carrier. 
The bearing assembly includes several conventional elements, including a 
plastic carrier with an axial sleeve, a radial wall nearly perpendicular 
thereto, and a cylindrical wall extending from the radial wall coaxially 
to the axial sleeve to form an annular space therewith. The carrier is 
moved axially toward and away from a set of declutching fingers by a 
conventional control mechanism, such as a fork or hydraulic cylinder. A 
radial bearing with inner and outer races fits with radial clearance 
within the annular space referred to above. 
The bearing assembly includes structure designed to allow self-centering of 
the bearing and to mount the bearing to the carrier. An attachment member 
has a cylindrical wall that surrounds the bearing and fits closely within 
the carrier cylindrical wall. A radial flange extends from the attachment 
member cylindrical wall radially inwardly past an axially outer face of 
the outer race of the bearing. Snap fingers on the cylindrical wall of the 
attachment member engage windows in the carrier cylindrical wall, thereby 
mounting the bearing to the carrier and compressing a suitable resilient 
element between the attachment member radial flange and the axially outer 
face of the outer race. The compressed resilient element axially biases 
the opposite face of the outer race into the radial wall of the carrier. 
The bias of the resilient element retains the outer race non-rotationally, 
but radially slidably, relative to the carrier radial wall. The rotational 
inner race of the bearing includes a contact member that is engageable 
with the declutching fingers of the clutch as the carrier member is moved 
axially theretoward. The radially slidable retention of the outer race 
allows the bearing to self-center relative to the clutch as the contact 
member engages the declutching fingers. 
The bearing assembly of the invention also includes additional structure 
that cooperates with the structure described above to give the added 
benefits of unitization of the assembly and shielding of the bearing. The 
contact member includes a retention and shielding portion of annular shape 
extending radially outwardly past the radial flange of the attachment 
member. The retention and shielding portion is axially spaced from the 
radial face of the outer race of the bearing a distance sufficiently small 
that, when the attachment member is detached from the carrier, the 
resilient element may axially expand sufficiently to bias the radial 
flange of the attachment member axially into the retention and shielding 
portion. This biasing serves to retain the attachment member to the 
bearing as a substantially rattle-free unit which may be separately 
handled apart from the carrier. Additionally, when the attachment member 
is joined to the carrier by engaging the snap fingers and windows to 
compress the resilient element, the radial flange of the housing member 
moves axially away from the retention and shielding portion of the contact 
a slight distance. This slight distance is just sufficient to allow the 
inner and outer races to rotate relative to each other when the contact 
member engages the declutching fingers, thereby serving to substantially 
exclude contaminants. Therefore, the retention and shielding member also 
cooperates with the radial flange of the attachment member to shield and 
protect the bearing. 
It is, therefore, an object of the invention to provide an improved 
self-centering bearing assembly for a clutch release mechanism in which a 
resilient element compressed between a radial flange of a detachably 
joinable attachment member and a face of one race of a bearing to allow 
self-centering of the bearing relative to the clutch also cooperates with 
a portion of a contact member on the other race by axially expanding to 
bias the radial flange of the attachment member into the portion of the 
contact member to maintain the attachment member and bearing together as a 
substantially rattle-free, separately handled unit. 
It is yet another object of the invention to provide such a clutch release 
bearing assembly in which, when the attachment member is joined to a 
carrier of the clutch release mechanism, the resilient element will be 
compressed and the radial flange will move axially away from the contact 
member portion just sufficiently to allow the bearing races to rotate 
relatively, whereby the contact member portion may also cooperate with the 
radial flange to shield the bearing. 
It is a further object of the invention to provide a clutch release bearing 
assembly of the type described incorporating a conrad-type radial bearing, 
in which the contact member is rigidly joined to a rotatable race of the 
bearing to thereby positively axially locate and space the retention and 
shielding portion of the contact member relative to a face of the other, 
non-rotatable race of the bearing.

Referring first to FIG. 1, a clutch release mechanism designated generally 
at 10 includes a carrier 12 that is moved axially toward and away from a 
set of declutching elements or fingers 14, shown in dotted lines, of a 
diaphragm-type clutch, not shown. Carrier 12 could be moved by any 
conventional control means, such as a fork or a hydraulic cylinder. 
Carrier 12, molded of plastic or similar material, includes an axial 
sleeve 16, a radial wall 18 generally perpendicular thereto, and a 
cylindrical wall 20 extending from radial wall 18 coaxially to, and 
forming an annular space with, axial sleeve 16. While a typical carrier 12 
need not necessarily include a cylindrical wall 20, it will generally 
include the axial sleeve 16 and radial wall 18, or very similar structure. 
Cylindrical wall 20 includes a circumferentially evenly spaced series of 
four rectangular windows or slots 22, each with a forward edge 24. As 
carrier 12 is moved, axial sleeve 16 would be guided on a pilot shaft, not 
shown, which would be rigid to the transmission case. 
Since declutching fingers 14 are spinning when the clutch is to be 
disengaged, some type of bearing assembly, designated generally at 26, is 
necessary to directly engage the declutching fingers 14 to transmit the 
axial thrust of carrier 12 thereto. 
Referring next to FIG. 3, bearing assembly 26 includes a radial bearing, 
designated generally at 28, mounted to carrier 12 in a manner described 
below by an attachment member, designated generally at 30. Bearing 28 
includes an outer race, designated generally at 32, an axially narrower 
inner race 34, and a complement of bearing balls 36 that are conrad 
assembled between races 32 and 34 and separated by a standard snap-in cage 
38. Races 32 and 34 are already axially located relative to each other by 
virtue of the conrad assembly, which is used to advantage in the 
embodiment of bearing assembly 26 disclosed. A pair of conventional snap 
shields 40 complete bearing 28. The wider outer race 32 has axially inner 
and outer faces 42 and 44, for a purpose described below. 
Still referring to FIG. 3, attachment member 30, stamped from sheet steel, 
is generally L-shaped in cross section, with a cylindrical wall 46 and an 
integral radial flange 48. Cylindrical wall 46 surrounds bearing 28 and 
has a diameter generally equal to the inside diameter of cylindrical wall 
20 of carrier 12. Radial flange 48 extends radially inwardly past outer 
face 44. A resilient element provided by a wavy washer 50, which serves 
two purposes described further below, is biased between radial flanges 48 
and outer face 44. Cylindrical wall 46 further includes four radially 
resilient snap fingers 52 which operate to detachably join it to carrier 
12 in a manner described below. 
A housing member, designated generally at 54, completes bearing assembly 
26. Housing member 54, also stamped of sheet steel, is axially rigid to 
inner race 34. Housing member 54 includes a cylindrical bearing seat 56 
and a curved contact member 58 that extends radially outwardly and axially 
inwardly therefrom. Bearing seat 56 is sized to snugly engage the outside 
of inner race 34. A retention and shielding portion 60, integrally stamped 
with contact member 58, has an annular shape and extends radially 
outwardly past the radial flange 48, and cooperates therewith as next 
described. 
To assemble bearing assembly 26, attachment member 30 is positioned with 
wavy washer 50 held between radial flange 48 and axially outer face 44. 
Inner race 34 is then friction fitted onto bearing seat 56 and pushed 
toward contact member 58 as far as it will go. Next, the terminal edge of 
bearing seat 56 is swaged over at 62 to retain inner race 34, and thus 
bearing 28, to housing member 54. This serves to positively axially locate 
and space retention and shielding portion 60 from axially outer face 44, 
because races 32 and 34 are already axially located relative to each other 
as described above. In effect, housing member 54 builds upon or extends 
that relative axial location. The axial spacing, denoted S in FIG. 3, is 
made sufficiently small that wavy washer 50 will axially expand to bias 
radial flange 48 into retention and shielding portion 60. This resilient 
bias acts to retain attachment member 30 to bearing 28 as a substantially 
rattle-free, separately handled unit apart from the carrier 12. Thus, wavy 
washer 50, which is designed to serve another function described below, 
also cooperates with retention and shielding portion 60 to unitize bearing 
assembly 26. 
Variations of the structure described may be imagined within the spirit of 
the invention. For example, wavy washer 50 could be eliminated as a 
separate part by stamping a wavy washer integrally with radial flange 48. 
In addition, housing member 54 could be eliminated as a separate piece by 
integrating it with inner race 34. A different bearing, such as an angular 
contact bearing with stamped races, would make the integration of housing 
member 54 with inner race 34 simple. However, additional structure, such 
as an inner axial sleeve, would be needed to give the complete positive 
axial location of the bearing races already present in the case of a 
conrad assembled bearing. 
Referring next to FIG. 2, attachment member 30 is detachably joined to 
carrier 12 by pushing bearing assembly 26 axially into the annular space 
between carrier cylindrical wall 20 and axial sleeve 16. The attachment 
member cylindrical wall 46 acts as an alignment surface as bearing 
assembly 26 slides into place and snap fingers 52 are biased radially 
inwardly by the inside of cylindrical wall 20. When the axially inner face 
42 of the wider outer race 32 engages the inside of radial wall 18, the 
snap fingers 52 will snap into slots 22, the ends thereof engaging the 
front edges 24 of slots 22. This mounts bearing 28 to carrier 12 and 
compresses wavy washer 50 sufficiently to hold outer race 32 so that it 
will not rotate relative to the carrier 12, but will still be radially 
slidable relative to axial sleeve 16. The narrower inner race 34 can, of 
course, freely rotate relative to the carrier 12. While bearing 28 will 
not necessarily be coaxial with the clutch after it is mounted, it may 
self-center, when contact member 58 engages declutching fingers 14, by 
virtue of the radial sliding action allowed by wavy washer 50. 
The amount of axial compression of wavy washer 50 necessary is determined 
by the resiliency of wavy washer 50 and how much holding force is needed 
for outer race 32. However, the axial spacing S is also sufficiently small 
so that the axial compression of wavy washer 50 that occurs will move 
radial flange 48 axially away from retention and shielding portion 60 to 
leave a gap G just sufficient to allow inner race 34 to rotate relative to 
outer race 32. Thus, retention and shielding portion 60 can also cooperate 
with radial flange 48 to shield bearing 28 from the entrance of 
contaminants because of the relatively small gap therebetween. There is no 
need for a separate cover member to fill or shield the space between the 
races 32 and 34, that function being served by structure that serves other 
purposes as well. The shielding function is enhanced if retention and 
shielding portion 60 is structurally part of a rotatable inner race 34 as 
shown, because the spinning action serves to centrifugally throw 
contaminants outwardly and away. 
Therefore, it will be seen that a bearing assembly is both unitized and 
shielded by a minimum of structural parts that cooperate with each other 
to serve more than one function. It is to be understood that the invention 
may be embodied in structures other than those herein disclosed, and is 
not to be so limited.