Rolling bearing

A rolling bearing assembly particularly adapted for wheel bearings in vehicles comprising an inner ring having at least one radially outwardly directed mounting flange, an outer ring and a plurality of rolling elements in the annular space between the inner and outer rings, at least one cap member secured to the inner ring having an annular rim section directed towards the outer ring and a seal ring secured to the outer ring in sliding engagement with said cap member under the rim thereof, said rim portion incuding at least one lubricant collector chamber defined in part by a radially inwardly facing wall portion and including at least one relatively small opening in said wall portion communicating with said lubricant collector chamber.

BACKGROUND AND SUMMARY OF THE INVENTION 
The present invention relates to rolling bearings and particularly to an 
improvement in wheel bearings for road vehicles such as automobiles. These 
bearing assemblies typically comprise an inner ring having a radially 
outwardly directed mounting flange, an outer ring, and a plurality of 
rolling elements in the annular space between the inner and outer rings 
and at least one cap mounted on the inner ring and arranged at one axial 
end of the outer ring, the cap having a rim section directed towards the 
outer ring and a sealing ring fastened to the outer ring and sliding 
radially on the cap under the rim section. 
Wheel bearing assemblies of this general type are known in the prior art. 
For example, in German Utility Patent No. 7,434,724, the assembly includes 
a space laterally open to the outer ring which is covered by the rim of a 
cap. In this instance, the sealing lips of the seal ring slide on the 
radial section of the cap which runs relatively cool in comparison with 
the inner ring. Consequently, the relatively sensitive sealing lips 
experience only a slight thermal stress during operation and therefore 
have a relatively long service life. When the sliding sealing lips of the 
seal ring start to wear after extended operation, the lubricant of the 
rolling bearing leaks out under the sealing lips of the seal ring then 
migrates to the space covered by the rim of the cap and accumulates there. 
This space, however, is laterally open towards the outer ring and 
consequently the lubricant is not always retained in this space with any 
degree of certainty. 
In accordance with another prior art assembly shown in German Patent 
Application No. 3,012,421.1 a lubricant collector is formed between the 
seal ring and the mounting flange of the inner ring and covered radially 
to the outside and laterally by the free end of the cap. The lubricant 
which is usually grease in this instance can freely move radially inwardly 
occasioned by radial driving shocks and corresponding mass forces 
affecting the lubricant and there penetrate into the space or interstice 
between the mounting flange of the inner ring and the seal ring of the 
outer ring. There is usually a predetermined amount of play in the rolling 
bearing and consequently, the interstice or space between the mounting 
flange and the seal ring varies continually by reason of the fact that the 
outer ring moves within certain limits relative to the inner ring. Thus 
the lubricant in the space or interstice may be pumped into the area of 
the rolling bearing under certain operating conditions and cause damage. 
With the above in mind, it is an object of the present invention to provide 
an improved rolling bearing specifically adapted for wheel bearing 
assemblies which is characterized by novel features of construction and 
arrangement producing a reduction in the wear of the sealing lips of the 
seal ring and assuring at the same time, that even in extreme cases or 
circumstances, lubricant does not migrate from the rolling bearing to the 
area outside the rolling bearing. Additionally, the rolling bearing 
assembly of the present invention can be produced economically and 
installed very simply. To this end, the rim of the cap is provided at its 
outer circumference with at least one lubricant collector closed off to 
the outside radially and laterally which is defined by a radially inwardly 
located wall of the rim and at least one small port or opening in the 
radially inwardly located wall which runs into the lubricant collector. By 
this arrangement, lubricant in the lubricant collector can only penetrate 
via small holes or ports which throttle the flow into the space or 
interstice between the seal ring and the cap. Thus when driving shocks 
occur during normal operation and momentary radially inwardly directed 
mass forces, only a very small quantity of lubricant can penetrate through 
the small openings into the lubricant space. Consequently, the danger of 
lubricant accumulation in the interstice is eliminated which as noted 
above under certain circumstances can migrate through the sealing slot 
and/or under the sealing lip of the seal ring and cause damage in the area 
of the rolling bearing, for example, on the friction surface of disc 
brakes. Further, since the sensitive sealing lips of the seal ring slide 
on the relatively cool portion of the cap, there is comparatively little 
wear in operation compared to the prior arrangement dicussed above where 
the engagement is with the inner ring which is heated by the disc brake 
and therefore the seal ring has a more favorable long, useful service 
life. 
Other more specific features of the invention described in more detail 
hereafter provide additional functional advantages. For example, in 
accordance with the principal embodiment, the lubricant collector is 
formed by a single annular space or chamber in the rim section of the cap 
which chamber is defined by a radially outer wall, a radially inner wall, 
and at least on the side thereof facing toward the outer ring by a side 
wall of the rim. By this arrangement a relatively large lubricant 
collector can be simply formed in the cap and at the same time maintain a 
compact construction of the rolling bearing. 
The lubricant collector opens radially inward in at least one closed slot 
or space formed between a radial wall section of the cap and a spaced 
confronting surface of the mounting flange of the inner ring. By this 
arrangement, there is not only an additional enlargement of the lubricant 
collector by reason of the connecting slot or space but also a more 
favorable heat insulation of the radial section of the mounting flange of 
the inner ring is attained. 
The radially extending section of the cap may be provided with a centering 
shoulder at its radial outer end for fastening the cap on the inner ring 
and this arrangement provides a relatively simple and easy means for 
centering the cap on the inner ring. Further, the cap is mounted in such a 
fashion that it is axially slidable on the inner ring. Accordingly during 
assembly, the cap can be supported at a greater distance from the outer 
ring so that the sensitive lips of the seal ring is not touching the cap 
and the outer ring can be freely placed in a tilted or eccentric position 
to the inner ring and the rolling elements easily inserted between the 
inner ring and outer ring in a conventional manner. After completely 
inserting the rolling elements, the cap can be axially adjusted against 
the outer ring and the seal ring and be fastened to the inner ring in the 
desired position. In accordance with the present invention, an elastic 
medium may be provided between the cap and the opposite mounting flange of 
the inner ring which axially adjusts the cap against the shoulder of the 
inner ring. By this arrangement, fabrication and installation of the 
rolling bearing are simplified because the cap is automatically pressed 
against the shoulder of the inner ring by the elastic medium. The cap is 
also supported on the inner ring without play even when comparatively 
large fabrication tolerences are present between the cap and the inner 
ring which facilitates economical manufacture of these parts. 
In accordance with another feature of the present invention, the lubricant 
collector is at least partly filled with a lubricant absorbing material. 
This provides additional means for holding the lubricant in the collector. 
Furthermore, the oil absorbing material serves as a heat insulating medium 
which inhibits the heat conduction from the inner ring to the slide 
surfaces of the temperature sensitive sealing lips of the seal ring of the 
cap. 
To further simplify and render production more economical, the cap may be 
formed from strip material and formed in a press or stamping process 
without machining which makes mass production possible.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring now to the drawings and particularly FIG. 1 thereof, there is 
illustrated a wheel bearing assembly particularly for an automobile which 
is generally designated by the numeral 1. The assembly comprises an inner 
ring 2, an outer ring member 3 and a plurality of rolling elements, in the 
present instance balls 4 arranged in two rows in the annular space between 
inner and outer raceways 2a and 3a formed in the confronting surfaces of 
the inner and outer rings. The inner ring is rotatably driven in a known 
manner by a driveshaft (not shown) connected to the inner ring and has at 
one axial end a radially outwardly directed mounting flange 5 to which the 
wheel rim 6 may be fastened by a series of circumferentially spaced bolts 
7. The outer ring 3 has a radially outwardly directed flange 8 for 
fastening the outer ring to the wheel mounting elements of the wheel 
frame. The assembly further includes a seal ring 9 which is mounted at one 
axial end in the bore of the outer ring 3 and slides on the extended 
portion of the inner ring on the land surface outboard of the inner 
raceway. A conventional cage 10 guides and spaces the balls. 
A seal ring 11 is mounted on the outer ring at the axial end thereof 
opposite the seal ring 9. In the present instance the seal ring 11 is 
supported on the outer peripheral surface 12 of the outer ring by means of 
a laterally extending guard ring 13 which also protects the seal ring 
against the impact from foreign objects, such as stones. The seal ring 11 
has a bifurcated outer sealing lips 14 which slide on a cap 15 mounted on 
the side of the outer ring facing towards the mounting flange 5. The cap 
may be produced without machining from strip material in a press and 
stamping process. The cap as illustrated has a radial section 16 against 
which one of the lips 14 slides, an outer axially extending section 17 
overlying and secured to the peripheral surface of the mounting flange 5 
and an inner axial section 18 defining a centering shoulder at its inner 
end which is axially slidable on the land surface of the inner ring 
outboard of the inner raceways. 
The cap 15 is of a predetermined configuration to define a lubricant 
collector chamber 20 which is illustrated is closed off radially to the 
outside and laterally. More specifically the annular collector chamber 20 
is formed by an annular space defined by a rim portion 19 of the cap 15. 
More specifically, the annular space is defined by the portion of the 
axial wall section of the cap which does not overlie the flange 5, 
designated by the numeral 21, a short axial wall section 22 spaced 
radially inwardly of the wall section 21 and a radial connecting wall or 
sidewall 23 connecting the wall sections 21 and 22. A plurality of 
circumferentially spaced small ports 25 which may be machined by stamping 
or drilling are formed in the connecting wall section 22. As illustrated 
on the side opposite the connecting wall 23, the lubricant collector 
chamber 20 is closed off by the side face or surface 5a of the mounting 
flange 5. Further, as illustrated, the lubricant collector chamber 20 has 
radially inwardly directed slot space 24 defined by the radial section 16 
of the cap and the confronting face 5a of the mounting flange 5. 
Consider now operation of the bearing assembly when the seal lips 14 which 
as illustrated slide on the radial and axial wall section 16 and 18 of the 
cap 15 show signs and wear after prolonged operation and lubricant such as 
grease which is packed in the annular space between the inner and outer 
rings 2, 3 starts to bypass the sealing lips. This migrating lubricant is 
collected at the radial inner wall 22 and passes through the ports 25 into 
the lubricant collector chamber 20. Accordingly, in the present instance, 
since the inner ring 2 rotates along with the cap 15 secured on the ring, 
the leaking lubricant is propelled effectively into the lubricant 
collector chamber 20 by centrifugal force. 
The parts of the bearing assembly are easy and economical to make and may 
be assembled readily in a very simple fashion. For example, in assembling 
the bearing, the wheel rim 6 is not initially bolted to the mounting 
flange 5 of the inner ring and therefore the cap 15 can be held at a 
greater distance on the inner ring 2 by the outer ring 3 so that the slot 
space 24 disappears. In this position, the sealing lips are out of contact 
with the cap. This permits easy insertion of the balls 4 between the inner 
and the outer rings since the outer ring 3 can be freely tilted or 
positioned eccentrically relative to the inner ring 2 without pinching or 
damaging the sealing lips 14 on the cap 15. After assembly of the balls 4 
and installation of the cage 10, the inner and outer rings are held 
concentrically together by the balls 4. The cap 15 can then be freely 
axially adjusted on the inner ring 2. In this position, the wheel rim 6 
can be bolted to the mounting flange 5 and in this position the cap 15 
abuts the wheel rim 6 and is restrained against lateral movement relative 
to the inner ring 2. 
There is illustrated in FIG. 2 a modified rolling bearing of a wheel 
bearing assembly in accordance with the present invention which is 
generally designated by the numeral 26. This embodiment of the invention 
is generally similar to that shown in FIG. 1 and comprises inner and outer 
rings with two rows of rolling elements, balls, in the annular space 
between the rings and a flange at one axial end of the inner ring to which 
the wheel rim 6 can be secured by suitable fasteners. In the present 
instance, however, the cap 15 has a series of circumferentially spaced 
small ports or openings 27 located in a frusto conical intermediate wall 
between the wall of the cap and the seal ring 11. The seal ring 11 has 
bifurcated circumferentially extending sealing lips 28 and 29 which engage 
the outer periphery of the cap 15 and straddle the openings or ports 27. 
By this arrangement, the outer lip 29 prevents penetration of moisture 
from the ambient atmosphere into the lubricant collecting chamber 20. In 
accordance with this embodiment of the invention, a narrow sealing slot 30 
is formed between the radial sidewall 23 of the cap 15 and the front 
terminal edge of the guard ring 13. This small sealing slot protects the 
sealing lips 28 and 29 from damage which may be occasioned by preventing 
ingress of large particles such as stones. 
In accordance with this embodiment, the cap 15 is also axially slidable on 
the inner ring to facilitate easy assembly of the elements of the rolling 
bearing 26 in the manner described above. In this instance, the terminal 
edge of the outer axial portion 15a of the cap has a radially inwardly 
directed bead-shaped groove 31 which snaps over the mounting flange 5 and 
seats on a beveled shoulder 5b of the mounting flange 5 to laterally lock 
the cap on the inner ring 2. 
FIG. 3 shows a further modified rolling bearing assembly in accordance with 
the present invention generally designated by the numeral 32. Here again 
the overall assembly is generally similar to that shown and described in 
connection with FIGS. 1 and 2. However, in this instance the lubricant 
collector chamber 20 is filled with an oil absorbing material, for 
example, an open pore foam-type plastic which may be injected into the 
lubricant collecting chamber 20. Further, in this instance relatively 
small ports or openings 33 are formed by narrow slots formed between a 
clip 34 pushed radially outward into the lubricant collector chamber 20 
and the corresponding cut edges of the wall 22. By this arrangement, 
lubricant bypassing the sealing lip 14 of the seal ring 11 is collected on 
the wall 22 and is conveyed into the lubricant collector chamber along the 
inclined radially outwardly directed surface of the clip 34. 
A further modified rolling bearing in accordance with the present invention 
is shown in FIG. 4. This arrangement is generally similar to that 
described previously. However, in this instance a sealing disc 35 of 
elastically compressible heat insulating material, for example, plastic is 
mounted between the radial section 16 of the cap 15 and the mounting 
flange 5. This sealing disc 35 seals the slot space 24 so that lubricant 
cannot penetrate this area. Moreover, the sealing disc 35 is used in this 
case as an elastic medium axially adjusting the centering shoulder 18 of 
the cap 15 against a shoulder 36 formed on the inner ring 2. The centering 
section 18 has a plurality of circumferentially spaced axially extending 
slits so that the shoulder can be snapped into the annular groove 38 from 
the outside surface of the inner ring 2. At the radially outer surface of 
the cap 15 facing away from the outer ring 3, radially inwardly directed 
recesses 39 are located on the outside surface of the mounting flange 5 by 
molding. By this construction the wheel rim 6 does not have to be removed 
when the cap 15 has to be moved axially away from the outer ring 3 in a 
direction toward the inner ring, for example, for assembling the rolling 
elements 4 or to replace for example, the seal ring 11. This is the case 
by reason of a large enough axial distance 40 between the front surface of 
the radially outer end of the cap 15 facing away from the outer ring 3 and 
the opposite side surface of the wheel rim 6. The cap 15 therefore, can be 
moved axially against the spring pressure of the sealing disc 35 so that 
the centering shoulder 18 is moved axially away from the shoulder 36. For 
this purpose, the cap can be grasped with a suitable tool which engages in 
the recess 39 to move the cap assembly axially against the shoulder 36 by 
the elastic sealing disc 35 and is readied for operation in this way. 
This cap assembly also has a collector chamber 20 formed by an annular 
space and in this instance narrow axial slots are formed in the radially 
inwardly located wall 22 which define relatively small open holes 41 in 
that wall. The wall configuration of the cap defining the collector 
chamber 20 is closely spaced axially to the front edge of the guard ring 
13 providing only a very narrow sealing slot 30. This keeps out relatively 
large particulate foreign matter. 
While particular embodiments of the present invention have been illustrated 
and described herein, it is not intended to limit the invention and 
changes and modifications may be made therein within the scope of the 
following claims. For example, in the embodiments illustrated and 
described, the bearing cap is made of strip material which does not 
require machining. It is to be understood, however, that the cap can also 
be made of castable materials, for example, in a die casting process. It 
is also possible to form the cap from solid stock by machining. 
Further, while the lubricant collector chambers of the various embodiments 
are continuous annular chambers, an alternate arrangement as shown in 
FIGS. 5 and 6 is possible. As illustrated, several lubricant collecting 
chambers may be formed which are arranged at the periphery of the cap and 
closed off for example, in a circumferential direction so that there are a 
series of circumferentially spaced lubricant collector compartments 
defined by radially inwardly located walls 20' of the cap. These radially 
inwardly directed walls 20' which divide the lubricant collector chamber 
into a plurality of compartments may be provided with at least one 
relatively small opening 41 and in this way, a movement of the lubricant 
in the collector chamber is restricted or inhibited in a circumferential 
direction. There is however, communication in a circumferential direction, 
provided below the divider walls 20' in the form of an annular space 22a. 
This precludes heavy accumulation of grease in only one pocket or 
compartment on the circumference which may produce an undesirable 
unbalance during rotation of the inner ring. This arrangement, therefore, 
would prevent a harmful or deleterious foaming of the lubricant in the 
lubricant collecting chamber which may occur in a rapidly accelerating 
automobile wheel with high acceleration forces affecting the lubricant. 
Finally, it is also possible to provide a mounting flange similar to the 
flange 5 on both sides of the inner ring and in this instance a cap 
fastened on the inner ring is present on both sides of the outer ring. In 
this instance, one of the flanges is removably mounted on the inner ring 
in order to permit assembly of the rolling elements. In the case of a two 
flange inner ring, the wheel hub may be mounted on the flange at one side 
and the brake elements (disc brake) may be mounted on the opposite side of 
the bearing. Each cap then has a radially extending section between the 
outer ring and the appropriate mounting flange with a rim portion of the 
cap continuing at its radial outer end directed towards the opposite side 
of the outer ring. The seal ring sliding radially under the rim portion on 
the appropriate cap and fastened to the outer ring is then present each 
time.