Bearings – Rotary bearing – Plain bearing
Reexamination Certificate
1999-09-29
2001-08-21
Hannon, Thomas R. (Department: 3682)
Bearings
Rotary bearing
Plain bearing
C384S210000, C384S903000
Reexamination Certificate
active
06276832
ABSTRACT:
BACKGROUND OF THE INVENTION
(1) Field of the Invention
The present invention pertains to a collapsible bearing retainer that holds a bearing in place on a shaft of an electromagnetic device and its method of use. More specifically, the present invention pertains to a bearing retainer having compliant tabs that project axially from the retainer, where the tabs are deformed after assembling the retainer between a C-ring and several washers and a bearing on the shaft to ensure end play between the washers and the bearing.
(2) Description of the Related Art
An example of a prior art bearing retainer and its method of use are depicted in
FIGS. 1-3
. Bearing retainers of this type are often used on shafts of electromagnetic devices, such as electric motors. The prior art bearing retainer
10
of
FIGS. 1-3
is also shown mounted on a shaft
12
of an electric motor. However, it should be understood that the bearing retainer
10
of the prior art is employed in other applications. It should also be understood that the bearing retainer of the invention yet to be described may be employed in applications other than the environment to be described.
Referring to
FIG. 1
, the internal windings (not shown) of the motor are to the left and the exterior of the motor is to the right. The shaft
12
is shown extending through a shaft opening
14
in an end bell or housing wall
16
of the motor. The dashed line
18
denotes the center axis of the shaft
12
. The shaft
12
is provided with an annular groove
20
around its exterior surface. A C-ring
22
is mounted on the exterior of the shaft and engages in the annular groove
20
, thereby providing an axially fixed stop on the shaft. The prior art bearing retainer
10
is next mounted on the shaft and moved into abutment against the C-ring
22
as shown in
FIG. 1. A
rubber washer
24
, a phenolic washer
26
and a metal washer
28
are then mounted in succession on the shaft. The bearing
30
is next mounted on the shaft in its position shown in FIG.
1
. The bearing
30
shown in the drawings is a spherical sintered powdered metal bearing however, other types of bearings may be mounted and retained on the shaft by employing the bearing retainer of the invention yet to be described.
In
FIGS. 1-3
, it is seen that the prior art bearing retainer
10
has a center hole
32
that is generally circular and is defined by a generally circular inner edge
34
of the retainer. The inner edge
34
of the retainer has an inner diameter that is only slightly larger than the exterior diameter of the shaft
12
. This enables the bearing retainer
10
to slide easily over the exterior of the shaft to its position shown in FIG.
1
. Also, the inner diameter of the bearing center hole
32
is slightly smaller than the exterior diameter of the C-ring
22
when the C-ring is mounted on the annular groove
20
of the shaft. This prevents the retainer from moving past the C-ring when an axial force directed to the left as viewed in
FIG. 1
is exerted on the retainer. From the inner edge
34
, the bearing retainer has a circular ring portion
36
that has axially opposite planar surfaces that extend radially outwardly to an annular flange
38
of the retainer. The annular flange
38
extends completely around the retainer and provides additional strength to the retainer. As can be seen in
FIG. 1
, the interior diameter of the annular flange
38
is determined so that the flange will engage over the exterior perimeter of the rubber washer
24
. The annular flange
38
is turned outwardly at the exterior perimeter edge
40
of the bearing retainer. The prior art bearing retainer is also provided with a key projection
42
that is bent axially outwardly from the inner edge
34
of the retainer.
The motor shaft, with the bearing
30
, the washers
24
,
26
,
28
, the bearing retainer
10
and the C-ring
22
mounted thereon, is then assembled into the housing enclosure for the motor. Many motor housing enclosures have two end shields or end bells that are assembled together over opposite ends of the shaft. Although only one bearing assembly is shown in
FIG. 1
, there could be a like bearing assembly mounted on the opposite end of the shaft or some other type of bearing assembly supporting the opposite end of the shaft. For simplicity only one bearing assembly is described here. In assembling the two motor housing portions or the two end bells of the motor together, an axial force is exerted by the end bell
16
on the bearing
30
. In one method of construction, the assembler pushes the two end bells together thereby creating the axial force exerted by the end bell
16
on the bearing
30
. Depending on the particular motor construction and the assembling of the motor, the axial force could press the bearing
30
, the washers
24
,
26
,
28
, the bearing retainer
10
and C-ring
22
tightly together. Many prior art motor enclosures for smaller electric motors have their two end bells secured together by epoxy. The epoxy is later cured in an oven. As the epoxy cures, it shrinks to a certain extent, thereby further increasing the axial load or axial force on the bearing
30
, the washers
24
,
26
,
28
, the bearing retainer
10
and the C-ring
22
.
The manual assembly of the motor and the shrinkage of the epoxy as it is oven cured could have a detrimental effect of creating an undesirable negative end play or no end play between the component parts of the bearing assembly. That is, the axial forces exerted by the motor end bell
16
on the bearing
30
, the washers
24
,
26
,
28
, the bearing retainer
10
and C-ring
22
cause these component parts to be pressed together with there being no end play or no axial spacing between adjacent parts. This situation can create friction between the metal washer
28
and the bearing
30
when the motor is operated. This friction, in turn, generates heat which can produce an undesirable burning smell when the motor is operated. This is particularly undesirable when the electric motor is used in a household appliance such as a dishwasher, clothes washer or clothes dryer.
What is needed to overcome the problem of friction heating of the prior art bearing is a way of retaining the bearing on the end of the shaft while ensuring a certain amount of end play between the bearing and the metal washer after the assembly of the electric motor is completed.
SUMMARY OF THE INVENTION
The present invention provides a bearing retainer that overcomes the disadvantages of the prior art bearing assembly discussed above by ensuring that a range of end play, preferably between 0.010 and 0.015 inches, is provided between the bearing and washer after the assembly of the motor has been completed.
The bearing retainer of the invention is designed to be employed in the same operative environment as the prior art bearing retainer and is employed in lieu of the prior art bearing retainer. The bearing retainer of the invention is positioned on the shaft between the C-ring
22
, and the washers
24
,
26
,
28
and bearing
30
. However, the bearing retainer of the invention differs from the prior art bearing retainer in certain aspects of its construction.
The bearing retainer of the invention is also preferably stamped from metal in a circular ring configuration. The bearing has a circular outer perimeter edge and a generally circular inner edge. However, the circular inner edge of the bearing retainer ring that defines its center hole is interrupted by several pairs of notches that extend radially through the material of the bearing retainer ring from the center hole. These pairs of notches define tabs between the notches of each pair. In the preferred embodiment, three tabs are formed in this manner. The tabs project radially inwardly toward the center hole of the bearing and terminate at distal edges. Each of the tabs is bent so that it angles slightly out of the plane of the bearing ring as it extends radially inwardly toward the center hole. In the preferred embodiment, the angled orientation of the tabs spaces the distal ends of the
Emerson Electric Co.
Hannon Thomas R.
Howell & Haferkamp LC
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