Title: Limited swivel self-aligning bearing assembly
Abstract: A motor shaft bearing assembly restricts the pivoting or swiveling movement of a self-aligning bearing supporting a motor shaft in a bearing seat. The bearing assembly provides projections adjacent the bearing seat that engage with an exterior surface of the bearing to restrict the movement of the bearing relative to the bearing seat. As an alternative or in addition to the projection adjacent to the bearing seat, a bearing retainer holding the bearing against the bearing seat is provided with a projection that engages into the exterior surface of the bearing to restrict the movement of the bearing relative to the bearing seat.
Patent Number: 6,974,258 Issued on 12/13/2005 to Borcherding, et al.
| Inventors:
|
Borcherding; Gary W. (Florissant, MO);
Dohogne; L. Ranney (Creve Coeur, MO)
|
| Assignee:
|
Emerson Electric Co. (St. Louis, MO)
|
| Appl. No.:
|
646977 |
| Filed:
|
August 22, 2003 |
| Current U.S. Class: |
384/192; 384/209 |
| Intern'l Class: |
F16C 023/04 |
| Field of Search: |
384/192,202-214
310/89,90
|
References Cited [Referenced By]
U.S. Patent Documents
| 2452352 | Oct., 1948 | Booth.
| |
| 3248955 | May., 1966 | Templeton.
| |
| 3754802 | Aug., 1973 | Keller.
| |
| 3794392 | Feb., 1974 | Scott.
| |
| 3947077 | Mar., 1976 | Berg et al.
| |
| 4014596 | Mar., 1977 | Kazama.
| |
| 4369387 | Jan., 1983 | Haar et al.
| |
| 4910424 | Mar., 1990 | Borcherding.
| |
| 5113104 | May., 1992 | Blaettner et al.
| |
| 5209596 | May., 1993 | Matczak et al.
| |
| 5857780 | Jan., 1999 | Newberg et al.
| |
| 6196726 | Mar., 2001 | Newberg et al.
| |
| 6252321 | Jun., 2001 | Fisher et al.
| |
| 6257767 | Jul., 2001 | Borcherding et al.
| |
Primary Examiner: Hannon; Thomas R.
Attorney, Agent or Firm: Thompson Coburn LLP
Claims
1. A bearing assembly comprising:
a spherical bearing having a center bore, the center bore having a center axis
that defines mutually perpendicular axial and radial directions, the bearing having
an exterior surface with a pair of end face surfaces at axially opposite ends of
the bearing and a convex surface between the pair of end face surfaces, the convex
surface extending around the bearing axis;
a bearing support having a bearing seating surface, the bearing seating surface
engaging the bearing convex surface;
a projection on the bearing support, the projection engaging with the bearing
exterior surface;
the projection engaging with at least one of the bearing end face surfaces; and,
the projection being one of a plurality of projections on the bearing support
that engage with the bearing end face surface.
2. The bearing assembly of claim 1, further comprising:
the pair of bearing end face surfaces being flat, parallel surfaces that extend
around the center bore.
3. The bearing assembly of claim 1, further comprising:
the bearing seating surface being on a wall having a hole through the wall, the
bearing being positioned in the hole.
4. A bearing assembly comprising:
a spherical bearing having a center bore, the center bore having a center axis
that defines mutually perpendicular axial and radial directions, the bearing having
an exterior surface with a pair of end face surfaces at axially opposite ends of
the bearing and a convex surface between the pair of end face surfaces, the convex
surface extending around the bearing axis;
a bearing support having a bearing seating surface, the bearing seating surface
engaging the bearing convex surface;
a projection on the bearing support, the projection engaging with the bearing
exterior surface;
the projection engaging with at least one of the bearing end face surfaces;
a disk supported on the bearing support adjacent the bearing; and,
the projection being on the disk.
5. The bearing assembly of claim 4, further comprising:
each bearing end face surface having a peripheral edge where the end face surface
intersects the convex surface; and,
the projection engaging into the at least one bearing end face surface at the
peripheral edge.
6. The bearing assembly of claim 4, further comprising:
the projection being one of a plurality of projections on the disk that engage
with the bearing end face surface.
7. The bearing assembly of claim 4, further comprising:
the disk having a center hole with a peripheral edge and the projection being
on the center hole peripheral edge.
8. The bearing assembly of claim 4, further comprising:
the bearing seating surface being on a wall having a hole through the wall, the
bearing being positioned in the hole, the wall extending radially outwardly from
the hole to a shoulder surface that projects axially outwardly from the wall; and,
the disk having an outer peripheral portion that engages with the shoulder surface.
9. A bearing assembly comprising:
a spherical bearing having a center bore, the center bore having a center axis
that defines mutually perpendicular axial and radial directions, the bearing having
an exterior surface with a pair of end face surfaces at axially opposite ends of
the bearing and a convex surface between the pair of end face surfaces, the convex
surface extending around the bearing axis;
a bearing support having a bearing seating surface, the bearing seating surface
engaging the bearing convex surface;
a projection on the bearing support, the projection engaging with the bearing
exterior surface;
the projection engaging into the bearing convex surface;
each bearing end face surface having a peripheral edge where the end face surface
intersects the convex surface; and,
the projection engaging into the convex surface between the end face surface
peripheral edges.
10. The bearing assembly of claim 9, further comprising:
the projection being one of a plurality of projections on the bearing support
that engages into the bearing convex surface.
11. The bearing assembly of claim 9, further comprising:
a disk supported on the bearing support adjacent the bearing; and,
the projection being on the disk.
12. The bearing assembly of claim 11, further comprising:
the projection being one of a plurality of projections on the disk that engage
into the bearing convex surface.
13. The bearing assembly of claim 11, further comprising:
the disk having a center hole with a peripheral edge and a plurality of resilient
tabs extending radially inwardly from the peripheral edge, the plurality of tabs
engaging with the bearing; and,
the projection being on one of the tabs.
14. The bearing assembly of claim 13, further comprising:
the bearing seating surface being on a wall having a hole through the wall, the
bearing being positioned in the hole, the wall extending radially outwardly from
the hole to a shoulder surface that projects axially outwardly from the wall; and,
the disk having an outer peripheral portion that engages with the shoulder surface.
15. A bearing assembly comprising:
a bearing having an exterior surface and a center bore with a center axis that
defines mutually perpendicular axial and radial directions relative to the bearing;
a bearing support having a bearing seating surface, the bearing seating surface
engaging the bearing exterior surface;
a disk supported on the bearing support adjacent the bearing; and,
a projection on the disk, the projection engaging into the bearing exterior surface;
the disk having a center hole with a peripheral edge and a plurality of resilient
tabs that extend radially inwardly from the peripheral edge, the plurality of tabs
engaging with the bearing exterior surface; and
the projection being on one of the tabs.
16. The bearing assembly of claim 15, further comprising:
the projection being one of a plurality of projections on the disk, the plurality
of projections engaging into the bearing exterior surface.
17. The bearing assembly of claim 15, further comprising:
the bearing seating surface being on a wall having a hole through the wall, the
bearing being positioned in the hole.
18. The bearing assembly of claim 17, further comprising:
the wall extending radially outwardly from the hole to a shoulder surface that
projects axially outwardly from the wall; and,
the disk having an outer peripheral portion that engages with the shoulder surface.
19. The bearing assembly of claim 15, further comprising:
the projection being one of a plurality of projections on the plurality of tabs,
the plurality of projections engaging into the bearing exterior surface.
Description
BACKGROUND OF THE INVENTION
(1) Field of the Invention
The present invention pertains to a motor shaft bearing assembly in which a self-aligning
bearing supports the motor shaft in a bearing seat to allow pivoting movement of
the motor shaft relative to bearing seat during motor assembly. In addition, the
bearing assembly includes a projection adjacent the bearing seat that engages into
an end face of the bearing to restrict the movement of the bearing relative to
the bearing seat. As an alternative or in addition to the projection adjacent the
bearing seat, a bearing retainer holding the bearing against the bearing seat is
provided with a projection that engages into the exterior surface of the bearing
to restrict the movement of the bearing relative to the bearing seat.
(2) Description of the Related Art
Various different types of bearing assemblies have been employed in mounting
rotating shafts to a supporting structure. For example, in the construction of
electric motors, bearing assemblies employing ball bearings, roller bearings, babbitt
bearings, and self-aligning bearings have been used in supporting the rotating
shaft of the electric motor in an end shield of the motor.
Of the above-mentioned different types of bearing assemblies, the bearing assembly
employing a self-aligning bearing is typically more cost efficient than the other
types of bearing assemblies. This is primarily because the use of ball bearing,
roller bearing or babbitt bearing assemblies requires expensive machining steps
to be performed on the motor end shield before the bearing assembly can be mounted
in the end shield.
The self-aligning bearing is typically constructed of sintered metal. The bearing
is formed with a generally spherical exterior surface and a pair of flat, axially
opposite end face surfaces. A shaft center bore passes through the bearing between
the end face surfaces.
In mounting the bearing on a motor end shield, the bearing is positioned on a
bearing seating surface that has been inexpensively cast on the motor end shield.
A bearing retainer having resilient fingers or tabs is assembled to the end shield.
The bearing retainer tabs engage against and urge the bearing against the bearing
seat of the end shield. The motor shaft can then be inserted through the bearing
center bore. The construction of the self-aligning bearing permits the motor shaft
and the bearing to pivot or swivel relative to the end shield bearing seat as the
motor is assembled.
However, there are certain situations in which the swiveling or pivoting
movement of the self-aligning bearing relative to the motor end shield bearing
seat is undesirable. Many small horsepower motors are assembled by bonding the
motor's stator between a pair of motor end shields. An epoxy is often used as the
adhesive. After assembly of the motor component parts between the end shields,
the component parts must not move relative to each other as the epoxy cures. The
ability of the self-aligning bearing to pivot or swivel relative to the end shield
bearing seat will at times allow the motor shaft to move relative to the end shield
before the epoxy is fully cured. This can result in defects in the motor construction.
For example, movement of the motor shaft can cause a cooling fan mounted on the
motor shaft to come into contact with a portion of the adjacent end shield.
To overcome the above disadvantage of self-aligning bearing assemblies used in
the construction of electric motors, a restraining force could be used on the bearing
to hold the self-aligning bearing stationary against the bearing seat. However,
because most self-aligning bearings are sintered bearings, increasing the force
on the bearing exterior to hold the bearing stationary against the end shield bearing
seat could deform the interior shaft bore of the bearing.
SUMMARY OF THE INVENTION
The self-aligning bearing assembly of the present invention overcomes the above-described
disadvantages associated with the prior art self-aligning bearing assemblies. This
is accomplished by providing a modified construction of the self-aligning bearing
assembly that limits or restricts the swiveling or pivoting movement of the bearing
relative to the end shield bearing seat. By restricting the movement of the self-aligning
bearing, the earlier described problems associated with using self-aligning bearings
are overcome.
In a first embodiment of the bearing assembly of the invention, a projection
is
provided on the end shield at a position adjacent the bearing seat surface. In
one embodiment, the projection is an integral part of the end shield. In an alternate
embodiment, the projection is on a disk assembled to the end shield. The projection
is positioned to be flush with or extend into one of the axially opposite end face
surfaces of the bearing when the motor is assembled. Because the projection extends
in an axial direction and is in contact with the end face surface of the bearing,
it does not present the problem of potentially deforming the interior shaft bore
of the bearing. The projection in contact with the bearing end face surface restricts
the swiveling or pivoting movement of the bearing relative to the end shield.
In a second embodiment of the bearing assembly of the invention, the bearing
retainer
is modified to restrict the movement of the bearing relative to the end shield
bearing seat. The bearing retainer resilient tabs that hold the bearing against
the bearing seat are provided with projections that extend into or dig into the
exterior surface of the bearing. The resilient tabs of the bearing retainer are
otherwise unaltered and the force they exert against the bearing pushing the bearing
against the bearing seat is not increased. This avoids any deformation of the bearing
interior shaft bore. The projections of the bearing retainer extending into or
digging into the exterior surface of the bearing restrict the swiveling or pivoting
movement of the bearing relative to the end shield bearing seat.
The use of the self-aligning bearing assemblies described above in the construction
of electric motors overcomes the problem of unintended movement of the motor's
component parts relative to the motor end shield while the epoxy employed in the
motor's assembly cures.
BRIEF DESCRIPTION OF THE DRAWINGS
Further features of the invention are set forth in the following detailed
description of the preferred embodiments of the invention and in the drawing figures wherein:
FIG. 1 is a partial, sectioned view of a first embodiment of the bearing assembly
of the invention supporting a motor shaft in a motor end shield;
FIG. 2 is a partial view of the end shield bearing seat surfaces with the bearing removed;
FIG. 3 is a partial, sectioned view similar to FIG. 1, showing a further embodiment
of the bearing assembly employing a disk assembled to the motor end shield;
FIG. 4 is a plan view of the disk of FIG. 3 removed from the motor end shield;
FIG. 5 is a partial, sectioned view of a further embodiment of the bearing assembly
employing a modified bearing retainer;
FIG. 6 is a plan view of the bearing retainer of FIG. 5, removed from the motor
end shield;
FIG. 7 is a side, sectioned view of the bearing retainer of FIG. 6; and
FIG. 8 is a partial, sectioned view of a further embodiment of the bearing assembly
employing a modified bearing retainer.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
FIG. 1 shows one operative environment of the bearing assemblies of the invention.
In the environment of FIG. 1, a bearing assembly is shown mounted in a portion
of an electric motor end shield. However, this is only one environment in which
the bearing assemblies of the invention may be used. Thus, the motor end shield
environment should not be interpreted as limiting. Because the use of bearing assemblies
in motor end shields is well-known, the end shield environment of FIG. 1 will only
be described generally.
The portion of the electric motor end shield shown in FIG. 1 includes a cylindrical
wall
12 having an interior shoulder surface
14. The shoulder surface
14 surrounds a shaft opening through the end shield. A plurality of radial
walls
16 extend radially inwardly from the end shield cylindrical wall
12.
In the embodiment shown, there were three radial walls
16 spatially arranged
around the shaft opening through the end shield. Each radial wall extends inwardly
from the end shield cylindrical wall
12 to a bearing seating surface
18
at the inner most end of the radial wall. The bearing seating surfaces
18
together comprise the bearing seating surface of the end shield.
A pair of end caps
22,
24 are mounted on the opposite ends of the
end shield cylindrical wall
12. The end caps
22,
24 function
to restrict contaminants such as dirt and dust from passing through the shaft opening
in the end shield and also function to prevent the leakage of lubricant through
the shaft opening.
A motor shaft
26 extends through the shaft opening in the end shield.
The
shaft
26 has an oil slinger
28 and a thrust washer assembly
32,
34 mounted on the shaft. A sintered, powdered metal, self-aligning bearing
36 is also mounted on the shaft.
The bearing
36 has a cylindrical center bore
38 that receives the
shaft. A center axis
40 of the bearing bore defines mutually perpendicular
axial and radial directions. The bearing center axis
40 is coaxial with
the center axis of the shaft and the center axis of the end shield shaft opening
defined by the bearing seating surfaces
18. The exterior surface of the
bearing has a spherical configuration defined by a convex surface
42 of
the bearing that extends completely around the bearing. The bearing exterior surface
also has a pair of parallel, flat, end face surfaces
44,
46 at axially
opposite ends of the bearing. The outer peripheral edges
48,
50 of
the bearing end face surfaces
44,
46 intersect axially opposite ends
of the bearing convex surface
42. The bearing convex surface
42 engages
against the bearing seating surfaces
18 of the end shield and supports the
shaft
26 for rotation relative to the end shield. As explained earlier,
the engagement of the bearing convex surface
42 with the bearing seating
surfaces
18 also permits some pivoting or swiveling movement of the shaft
26 relative to the end shield.
A disk-shaped retainer ring
52 holds the bearing
36 in engagement
with the bearing seating surfaces
18. The retainer ring
52 is pressed
into the end shield cylindrical wall
12 and engages against one side of
the end shield radial walls
16. The ring
52 has a peripheral portion
54 that engages against the end shield shoulder surface
14 to hold
the ring in place adjacent the bearing
36. The ring has a circular inner
edge
56 that surrounds a shaft hole through the ring. A plurality of resilient
fingers or tabs
58 project radially inwardly from the ring inner edge
56
and engage against the convex surface
42 of the bearing
36. These
resilient tabs
58 exert a force on the bearing
36 that holds the
bearing against the bearing seating surfaces
18. However, the force exerted
by the resilient tabs
58 is not sufficient to potentially deform the center
bore
38 of the bearing.
The construction of the bearing assembly of the invention described to this point
is, for the most part, conventional. The bearing assembly of the invention differs
from prior art bearing assemblies in that it employs a plurality of projections
adjacent the bearing seating surfaces
18. The projections are positioned
to engage with the self-aligning bearing
36 to limit the pivoting or swiveling
movement of the bearing relative to the bearing seating surfaces.
A first embodiment of the projections
62 of the bearing assembly of the
invention is shown in FIGS. 1 and 2. The projections
62 are positioned radially
inwardly from the bearing seating surfaces
18 and are formed as integral
parts of the end shield. In FIG. 2 only one projection
62 per bearing seating
surface
18 is shown. This one projection
62 is centered relative
to the bearing seating surface
18. However, other positionings of the projections
62 adjacent the bearing seating surfaces
18 may be employed. For
example, a pair of projections
62 could be provided adjacent each bearing
seating surface
18 at circumferentially opposite ends of the bearing seating
surface. The projections
62 are positioned so that they will engage with
the peripheral edge
50 of the bearing end face surface
46. This avoids
any potential deformation of the bearing center bore
38. The bearing is
installed with a force that causes the projections to deform the relatively soft,
porous bearing material. This ensures that contact will always be made between
the bearing and the projections regardless of the tolerance of the two parts. The
engagement of the projections
62 with the bearing end face surface
46
functions to limit the swiveling or pivoting movement of the bearing
36
relative to the bearing seating surfaces
18. The resilience of the disk
also acts to return the bearing to its proper position relative to the bearing
seat if a force causes the bearing to be initially swiveled from its proper position.
By limiting the pivoting or swiveling movement of the bearing
36 relative
to the bearing seating surfaces
18, the disadvantages associated with the
prior art self-aligning bearings are overcome.
FIG. 3 shows a variant embodiment of the bearing assembly of FIG. 1. Many of
the component parts of the bearing assembly of FIG. 3 are the same as those of
FIG. 1, and are identified by the same reference numbers employed in FIG. 1. FIG.
3 differs from FIG. 1 in that the projections
62 of FIG. 1 that were integral
parts of the end shield and formed adjacent the end shield bearing seating surfaces
18 are no longer present. Instead of the end shield projections
62,
a circular disk
64 with projections
66 is employed to limit the pivoting
or swiveling movement of the self-aligning bearing
36 relative to the bearing
seating surfaces
18.
The disk
64 is shown in FIG. 4 and is basically a thin metal disk having
an outer, circular peripheral edge
68 and an inner, circular edge
72.
The projections
66 are arcuate segments of the disk at the disk inner edge
72. As shown in FIG. 3, the arcuate projections
66 project axially
from one surface
74 of the disk.
The disk
64 is installed on the end shield by pressing the disk into the
end shield cylindrical wall
12 until the disk surface
74 with the
projections
66 engages against the radial walls
16 of the end shield.
The disk could also be bonded to the end shield or secured by other means. The
projections
66 on the disk
64 project axially from the disk into
the shaft opening defined by the bearing seating surfaces
18. With the bearing
36 held against the bearing seating surfaces
18 by the retainer ring
52, the disk projections
66 contact the bearing end face surface
46. The engagement of the projections
66 with the bearing end face
surface
46 restricts the pivoting or swiveling movement of the bearing
36
relative to the bearing seating surfaces
18.
FIG. 5 shows a further embodiment of the bearing assembly of the invention.
Many of the component parts of the bearing assembly of FIG. 5 are the same as those
of FIG. 1, and are identified by the same reference numbers employed in FIG. 1.
FIG. 5 differs from FIG. 1 in that the projections
62 of FIG. 1 that were
integral parts of the end shield and formed adjacent the end shield bearing seating
surfaces
18 are no longer present. Instead of the end shield projections
62, a modified bearing retainer is employed to restrict the pivoting or
swiveling movement of the bearing
36.
The bearing retainer
82 is shown removed from the motor end shield
12
in FIGS. 6 and 7. Like typical bearing retainers, the bearing retainer
82
is a stamped metal part. It is formed with a planar ring portion
84 with
a circular inner edge
86. A peripheral portion
88 of the bearing
retainer extends around the outer periphery of the ring portion
84. The
ring portion
84 has opposite interior
92 and exterior
94 surfaces.
The ring portion exterior surface
94 seats against the radial walls
16
of the end shield
12 as shown in FIG. 5.
The outer peripheral portion
88 of the bearing retainer
82 is formed
with a plurality of arcuate flanges
96. The arcuate flanges
96 project
at an angle from the ring portion
84. The width of the ring portion
84
and the angled orientation of the arcuate flanges
96 allows distal edges
of the flanges to dig into the shoulder surface
14 of the end shield cylindrical
wall
12 when mounting the retainer to the end shield. This securely holds
the bearing retainer
82 in its position shown in FIG. 5. As shown in FIG.
6, the arcuate flanges
96 are separated from each other by pairs of notches
98 and radially projecting prongs
102 between the pairs of notches.
The distal ends of the prongs
102 also engage and dig into the material
of the end shield shoulder surface
14 to securely hold the bearing retainer
82 to the end shield
12.
A plurality of arcuate ridges
104 are formed in the bearing retainer ring
portion
84 at the inner edge
86 of the ring portion. The arcuate
ridges
104 are spatially arranged around the ring portion inner edge
86
at positions radially opposite the gaps formed by the notches
98 in the
bearing retainer peripheral portion
88. Each of the arcuate ridges
104
project at an angle from the ring portion interior surface
92 to strengthen
the ring portion
84 in the area of the notches
98.
Resilient tabs or fingers
106 project radially inwardly from the
inner edge
86 of the bearing retainer ring portion
84. As shown in
FIG. 6, the resilient tabs
106 are spatially arranged between pairs of the
arcuate ridges
104. The tabs
106 are oriented at an angle relative
to the bearing retainer ring portion
84 and engage against the exterior
surface of the bearing
36 when the bearing retainer
82 is installed
on the end shield
12 in the position shown in FIG. 5. The resiliency of
the tabs
106 urges the bearing
36 against the bearing seating surfaces
18 of the end shield. However, the tabs
106 do not exert a sufficient
force on the bearing
36 that would cause the center shaft hole
38
of the bearing to deform.
The construction of the bearing retainer
82 described to this point is,
for the most point, conventional. The construction of the bearing retainer
82
of the invention differs from that of prior art bearing retainers in that pairs
of fold over projections
108 are provided on the distal ends of each of
the resilient tabs
106. As shown in FIG. 6, each resilient tab
106′
is provided with fold over projections
108 at the radially inward ends of
the tabs. In variant embodiments, different numbers of projections could be formed
on the distal ends of each of the tabs
106. The resilience of the tabs
106
causes the projections
108 of each tab to engage with and dig into the exterior
surface of the bearing
36 as shown in FIG. 5. The engagement of the projections
108 into the bearing convex surface
42 as shown in FIG. 5 restricts
the pivoting or swiveling movement of the bearing
36 relative to the bearing
seating surfaces
18.
FIG. 8 shows a further embodiment of the bearing assembly of the invention.
Many of the component parts of the bearing assembly of FIG. 8 are the same as those
shown in FIG. 5, and are identified by the same reference numbers employed in FIG.
5. FIG. 8 differs from FIG. 5 in that the projections
112 of the bearing
retainer
82 are not formed on the distal ends of the resilient tabs
106
of the retainer, but are formed into interior portions of the resilient tabs
106.
The projections
112 are formed in the tabs
106 by extruding holes
into the interior portions of the tabs. This produces the projections
112
around the extruded holes. The resilience of the bearing retainer tabs
106
causes the projections
112 to engage with and dig into the convex surface
42 of the bearing
36. The engagement of the projections
112
into the bearing surface
42 restricts the pivoting or swiveling movement
of the bearing
36 relative to the bearing seating surfaces
18.
The various embodiments of the bearing assemblies of the invention described
above overcome the problems associated with the use of self-aligning bearings by
restricting or limiting the pivoting or swiveling movement of the bearings in their
bearing seats. Furthermore, the bearing assemblies of the invention overcome the
problem of excessive pivoting or swiveling movement of the motor shaft bearings
without resorting to more expensive ball bearing, roller bearing or babbitt bearing assemblies.
While the present invention has been described by reference to specific embodiments,
it should be understood that modifications and variations of the invention may
be constructed without departing from the scope of the invention defined in the
following claims.
*
