Note: Descriptions are shown in the official language in which they were submitted.
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TITLE
SELF-LOCKING METAL CAP AND PLASTIC BEARING
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to bearing cups for the ends of
universal joint trunnions and, more particularly, to self-
locking metal bearing cap and plastic bearing assemblies
which immediately retain the journal cross within the
yokes of a universal joint.
2. Summary of Related Art
Universal joints are well known devices employed for
interconnecting two members or shafts adapted to rotate
about respective non-aligned and/or angularly adjustable
axes of rotation. Universal joints of this type are
widely used in the steering mechanism of vehicles.
Typically, such universal joints include a journal cross
formed by a central body portion having four outwardly
extending and circumferentially equally spaced trunnions.
The trunnions are coplanar and are arranged in opposed,
axially aligned pairs disposed at right angles relative to
one another. A bearing cup is rotatably mounted over the
end of each of the trunnions, and each of the two opposed
pairs of bearing cups is secured within a yoke. The yokes
are respectively secured to the rotatable members to
provide the universal joint con~ection therebetween.
Generally, the peripheral outer surface of the
trunnion and the inner wall of t-le associated bearing cup
are spaced from each other and an annulus of needle
bearings is disposed within this space. The needle
bearings rollingly engage the bearing wall or race and the
trunnion to provide substantially frictionless rotation
therebetween. A separate seal comprised of a ring of a
resilient elastomeric material is required to seal the
opening which exists between the open end of the bearing
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cup and the trunnion. This separate seal is generally
mounted on the bearing cup at the time of its assembly.
When installing universal joints of this type, the
following assembiy process is frequently employed. A pair
of opposed trunnions on the journal cross are positioned
within the pair of bores formed in the arms of a yoke. A
bearing cup is inserted axially through one of the bores
on the yoke, with the open end of the bearing cup
receiving the end of the associated trunnion. A snap ring
is then mounted within the bore behind the closed end of
the bearing cup to prevent radial outward movement of the
bearing cup away from the trunnion. Another bearing cup
is inserted through the bore in the opposite arm of the
yoke and similarly secured in position by a snap ring. A
yoke is then mounted on the remaining pair of opposed
trunnions in a like manner.
SUMMARY OF ~HE INVENTION
The present invention relates to a self-locking metal
20 cap for a bearing race which is adapted to receive a `
journal cross trunnion and be secured within a bore of the
yoke of a universal joint assembly. A metal bearing cap
having an open end, and adapted to carry a bearing race in
its interior, includes a plurality of resilient, outwardly
extending tabs or detents formed integrally with and
spaced around the metal cap inwardly from its open end.
These tabs immediately lock upon insertion to retain the
bearing cup within a bore of the yoke after insertion
therein. This novel construction eliminates the need for
a snap ring, an associated snap ring groove, and the
additional assembly required therefor.
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A plastic bearing is preferably mounted within the
self-locking metal cap. The plastic bearing comprises a
monolithic open-ended plastic bearing cup and an integral
lip seal formed about the inner circumference of the open
end of the plastic bearing cup, which obviates the need
for a separate seal. At least one radial groove and at
least one axial groove are formed in the inner surface of
the bearing cup for lubrication purposes.
BRIEF DESCRIPTION OF THE DRAWINGS
The above, as well as other advantages of the present
invention, will become readily apparent to those skilled
in the art from the following detailed description of a
preferred embodiment when considered in the light of the
accompanying drawings in which:
Fig. 1 is a longitudinal elevational view, shown
partially in longitudinal section, of the assembly of one
o~ the rotational mem,bers of a universal joint including
self-locking metal cap and plastic bearing assemblies in
accordance with the present invention:
Fig. 2 is an enlarged sectional view of a self-
locking metal cap and bearing race shown in Figure l; and
Fig. 3 is a plan view taken substantially along line
3-3 of Fig. 2.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring now to the drawings, there is illustrated
generally at 8 in Figure 1 a portion of a universal joint
assembly including a yoke 10 having a pair of arms 12 and
14. A journal cross 16 is mounted between the arms 12, 14
of the yoke 10 via bearing cup assemblies 18 received in
bores 19 in the arms 12, 14. The journal cross 16
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includes a central body portion 20 having four outwardly
exl:ending and circumferentially equally spaced trunnions
22 The trunnions 22 are disposed in a single plane at
ri~ht angles relative to one another. A bearing cup
assembly 18 is rotatably mounted over the end of each of
the trunnions 22, and each of the opposed pair of bearing
cup assemblies 18 is secured to the yoke 10 within bores
19 formed in the arms 12, 14 thereof. A pair of the yokes
10 are secured each to one of a pair of rotatable members
(not shown) to provide a universal joint connection
therebetween.
The bearing cup assembly 18 of the present invention,
as best seen in Figure 2, is comprised of a self-locking
metal cap 24 within which is seated a bearing cup 26 of a
suitable material as will be hereinafter discussed. The
metal cap 24 is provided with an open end and is adapted
to receive a suitable bearing device for carrying the end
of the trunnion 22 as part of a universal ~oint assembly.
The bearing device may be of any suitable type, such as
the annulus of needle bearings which is typically used in
universal joint bearing cups. Preferably, however, the
bearing device is a plastic bearing cup in accordance with
another aspect of the present invention, as is described
in detail hereinafter.
The metal cap 24 is further provided with a plurality
of resilient, outwardly extending tabs 32 formed
integrally as by being struck from the circumferential
wall of the cap. The tabs 32 function to securely retain
the metal cap 24 within the bore 19 in the yoke arms 12 or
14 once the metal cap 24 has been inserted through the
bore 19. The tabs 32 are formed to slope outwardly from
the wall of the metal cap 24 and away from the open end
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thereof. Thus, as the open end of the metal cap 24 is
inserted into the associated bore, and since the outer
diameter of the metal cap 24 is substantially equal to the
diameter of the bore, the resilient tabs 32 are deflected
inwardly to permit insertion of the metal cap 24 through
the bore 19. Once the distal ends of the tabs 32 pass
completely through the bore 19, the tabs 32 return to
their outwardly extending position so that the distal ends
of the tabs 32 engage the inner surface of the yoke arm 12
or 14. The tabs 32 thereby provide immediate and
automatic locking of the bearing cup assembly 18 upon
insertion within the bore 19 of the yoke arm 12 or 14.
To assure proper alignment of the metal cap 24 within
the bore of a yoke arm 12 or 14, at least three tabs 32
must be formed in the metal cap. Preferably, four such
tabs 32 are formed, equally spaced around the
circumference of the metal cap. The tabs 32 may be formed
in any suitable shapq and by any suitable method and, as
indicated above, are preferably formed by striking
sections from the wall of the metal cap 24.
In the preferred embodiment, the metal cap 24 retains
a plastic bearing cup 26. The bearing cup 26 is formed as
a one-piece member having an open end, and an integral lip
seal 28 formed about the inner circumference of the open
end. The bearing cup 26 is fixedly mounted within the
metal cap 24 in any suitable manner, such as by press
fitting or by means of an adhesive. Suitable adhesive
materials include epoxy resin adhesives. The plastic
bearing cup 26 is provided with a chamfered edge 34 at the
outer circumference of the closed end thereof to
facilitate assembly within the metal cap 24. The metal
cap 24 strengthens and reinforces the plastic bearing cup
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26, and retains it in proper alignment with respect to the
trunnion 22 and the yoke arms 12 and 14.
The inner diameter of the bearing cup 26 is
substantially equal to or slightly smaller than the outer
diameter of the trunnion 22, so that the bearing cup 26
may be snugly mounted on the trunnion 22 as by a light
press fit. As seen in Figure 1, the integral lip seal 28
extends outwardly beyond the end surface of the bearing
cup 26 and is adapted to sealingly engage a shoulder 30
formed on the trunnion 22. The integral lip seal 28
thereby provides a seal to prevent the loss of lubricant
from the interior of the bearing cup 26, as well as to
prevent the introduction of foreign material into the
bearing cup 26. By integrally moldiny the lip seal 28
with the bearing cup 26, the need for a separate seal
member, and the time and effort expended on assembly of
the same, is eliminated.
The plastic bea~ing cup 26 is furthèr formed in its
inner surface with one or more elongate grooves extending
radially along the end wall and axially along the si~e
wall of the bearing cup 26 for containing and distributing
lubricant at the interface between the bearing cup 26 and
the trunnion 22. To this end, an axial groove 36 should
be positioned so as to communicate with an associated
,radial groove 38. In a preferred embodiment, as
illustrated in Fig. 3, the plastic bearing cup 26 is
provided with three circumferentially equally spaced axial
grooves 36 each in communication with an associated radial
groove 38, the three grooves 38 radiating from an
intersection at approximately the center of the closed end
of the bearing cup 26.
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The plastic bearing cup may be formed of any suitable
plastic material. It has been found, by way of example,
that thirty (30) percent glass-filled nylon 6,6 as well as
thirty (30) percent glass-filled nylon 4,6 are materials
well-suited for the bearing cup.
When assembling universal joints of the type
including the self-locking metal cap and plastic bearing
cup assembly 18 in accordance with the present invention,
a pair of opposed trunnions 22 on the journal cross 16 are
positioned within the pair of bores formed in the arms 12
and 14 of a yoke lO. The grooves 36 and 38 in the inner
surface of the plastic bearing cup 26 are filled with
lubricant, and the open end of the bearing cup assembly 18
is inserted through one of the bores 19 of the yoke 10,
with the open end of the plastic bearing cup 26 receiving
the end of the associated trunnion 22 as by means of a
light press fit. When the tabs 32 formed in the metal cap
24 pass completely t~rough the bore 19, they return to
their outwardly extending position so that the distal ends
thereof engage the inner surface of the yoke arm 14. The
cap 24 thus provides immediate and automatic locking of
the bearing cup assembly 18 upon insertion within the bore
19 of the yoke arm 14. A second bearing cup assembly 18
is inserted through the bore in the opposite arm of the
yoke 10 in a like manner, and similarly secured in
position.
In accordance with the provisions of the patent
statutes, the present invention has been described in what
is considered to represent its preferred embodiment.
However, it should be noted that the invention can be
practiced otherwise than as specifically illustrated and
described without departing from its spirit or scope.
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