Note: Descriptions are shown in the official language in which they were submitted.
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BACK~ROU~ID OF THE INVENTION
Conventional methods of sealing shaft bearings against
lubricant loss utilize flexible seals, metal retainers or "O"
rings which require material contact. If the seal is held
stationary in the bearing housin~, the material or frictional
contact is with the rotating shaft journalled in the bearing.
If the seal is mounted on the shaft, the frictional contact is
with the housing supporting the bearing journalling the shaft.
For low wear characteristics and efficient operation, high speed
motors or mechanism utilizing ball bearings to journal the shaft
require extremely low friction drag coefficients. ~he ideal
design is one in which the seal is carried by the shaft and has
no material contact with the wall of the housing cavity in which
the ball bearing supporting the shaft is mounted.
It is an ob~ect of the present invention to provide
a lubricant seal having no material contact with the stationary
housing and which is capable of absorbing excess oil from the
housing cavity when the system is at rest to prevent leakage
past the shaft. It is a further object that the lubricant seal
be capabla at high speeds of centrifuging oil into the rapidly
rotating inner race of the bearing to lubricate the balls of the
bearing.
SUMMARY OF THE INVENTION
The present invention relates to a lubricant seal
for an oil lubricated ball bearing journalling a shaft within
the cavity of a stationary housing. The lubricant seal comprises
an annular rigid oil slinger affixed to the shaft within the
cavity. The oil slinger is formed of an oil absorbent material
adapted at low or nonrotational speed of the shaft to absorb ex-
cess oil within the housing cavity to prevent leakage past theshaft and at high speed to centrifuge oil into the bearing.
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Preferably, the oil slinger and an adjacent wall o~ the
cavity have coacting noncontactiny portions forming a labyrinth
further inhibiting passage of oil to the exterior of the cavity.
Further, preferably, the oil absorbent material has a porosity of
30~-40% by volume and may be of metal or plastic.
DESCRIP:TION OF THE DRAWING
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Further features and advantages of the present invention
will be made more apparent as this description proceeds, reference
being had to the accompanying drawing wherein the single figure
illustrates in cross section a typical embodiment of the present
invention.
DESC~IPTION OF THE INVENTION
. . . _ . .
Referring to the drawing, one end of a sha~t 11 is
rotatably supported by a conventional ball bearing 12 within
the cylindrical bore or cavity 13 of a stationary housing 14.
The ball bearing 12 comprises an inner race 15 that receives an
extension end 16 of the shaft ll. The outer race 17 of the
bearinq 12 fits within the cylindrical bore or ca~ity 13 and
the inner and outer races are operatively separated by conventional
balls 18, the balls being positioned by a.ball cage l9.
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.~ More particularly,.~t~ere is provided: ~
a lubricant seal for an oil lu~ricated bearing journalling
a sha~t within a cavity of a housing,
the sha~t extending from the bearing through an aperture
in a wall of the housing externally of the latter,
~ the cavity ~eing in communication with the exterior of
the housing through said aperture, the aperture having a smaller
diameter than the cavity,
the lubricant seal comprising an annular rigid oil
slinger affixed to the shaft within the cavity between said bear-
ing and said housing wall, and having a diameter greater than that
of the aperture,
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the oil slinger being formed of an oil absorbent material
located in said cavity so that at low or non-rotational speed of
the shaft to absorb oil from within the housing cavity to prevent
leakage past the shaft and at high speed to centrifuge oil into
the bearing.
There is also provided:
in combination,
a housing having a wall and a cavity within the housing
interiorly of the wall, the cavity being sealed against oil leakage
except for an aperture in the housing wall, the aperture having a
smaller diameter than the cavity,
a shaft projecting through the aperture into the cavity,
oil lubricated bearing means mounted within the cavity
in which the shaft is rotatably journalled,
and a lubricant seal comprising a rigid, annular, oil
slinger formed of an oil absorbent material,
the oil slinger being a~fixed to the shaft within the
cavity between the bearing means and the apertured wall, and
having a diameter greater than that of the aperture,
the oil slinger being rotatable with the shaft and
located in said cavity so that at low or non-rotatable speed to
absorb excess oil from the cavity to prevent leakage through the
apertured wall past the shaft to the exterior o the housing
and at high speed to centrifuge oil into the cavity for deposition
on the bearing means.
There is urther provided:
in combination,
a housing having end walls and a cylindrical side wall
forming a cavity in the housing,
the cavity being substantially sealed against oil leakage
except for an aperture in one end wall,
a sha~t projecting through the aperture into the cavity,
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oil lubricated bearing means mounted within the cavity
rotatably journalling the shaft,
a preinjected quantity of oil entrapped within the housing,
and a lu~ricant seal comprising a rigid annular oil
slinger formed of an oil absorbent material,
the oil slinger being affixed to the shaft within the
cavity between the bearing means and the apertured end wall,
the oil slinger having on its side facing the bearing
means a radially extending surface portion unimpededly exposed
to the bearing means and also having its peripheral surface in
close non-contact running relation to a portion of the cylindrical
side wall adjacent the apertured end wall,
the apertured end wall and the oil slinger on its side
facing the apertured end wall having radially and axially
overlapping portions having a close running fit to each other forming
a la~yrinth inhibiting passage of oil to the outside o the housing,
the oil slinger being rotatable with the shaft and at low
or non-rotatable speed being capable of absorbing oil from the
cav;ty to pxevent leakage throuyh the labyrinth to the exterior of
the housing and at high speed to centrifugally restore the
absorbed oil to the cavity fox deposition on the bearing means.
The bearing 12 is positioned on the shaft extension 16
in spaced relation to the shoulder 20 of the main shaft 11 by a
spacer 21 and an annular oil slinger 22, both the spacer 21 and
slinger 22 being rotatable with the shaft 11. The spacer 21,
slinger 22 and ball bearing 12 are retained on the shaft extension
16 by a retainer plate 23 secured by a center bolt 24.
At its outer end the cylindrical bore 13 o~ the
housing 14 is closed by an outer bearing retainer 25 having an
oil cap 26 plugging a central aperture 27 in the retainer. At
its opposite or inner end, the end receiving the shaft 16, the
housing 14 has a radially extending end wall 28 terminating
in an axially inwardly extending ring or cylindrical flange 29.
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The in~ernal diameter of the flange is IQinu~ely laryer than the
outside diameter of the spacer 21.
The oil slinger 22 has an annular body portion 31 ter-
minating in an axially outwardly extending flange 32 having an
interfitting relation with an annular groove 33 in the
housing end wall ~8 and cylindrical flange 29. This interfitting
relationship provides a clearance slot 34 which follows a laby-
rinth path from the housing cavity 13 to the atmosphere.
As shown in the drawiny, the peripheral surface of the
oil slinger flange 32 is an inclined plane of increasing radial
dimension from its end adjacent the apertured end wall 28 of the
housing 14 toward the end adjacent the bearing means whereby
during high speed rotation of the slinger oil movement along the
inclined plane is toward the bearing means.
The foregoing describes the physi~al characteristics
of a typical shaft and bearing assembly embodying the present
invention. It will be understood that these characteristics
may be subject to variation. Of interest, however, in connection
with the present invention is the material composition of the oil
slinger 22.
The oil slinger 22 is more than just a rotating disc
adapted to pick up oil from a reservoir portion of the housing
cavity and to centrifuge the oil on a shaft or bearing as
disclosed in U.S. patent 1,701,707 issued February 12, 1929
to G. Eveno for a "Lubricating Bearing for Journal Boxes".
It is also more than a simple distributor of oil adrnitted to the
housing cavity as~disclosed in U~S. patent 3,532,399 issued
October 6, 1970 to P. W. Gray for a "Labyrinth Sliny Seal". The
slinger 22 is a rigid annular member which is oil absorbent
and is therefore capable of acting as an oil storage member
when the shaft and bearing are at rest or rotating at a low
speed, thus preventing leakage of the oil between the shat and
the housing.
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At high speeds, even on the order of 85,000 rpm, the oil
contained within the slinger 22 is centrifuged into the ball
bearing to provide a suitable quantity of lubricant on the moving
parts. As the unit slows down or comes to rest, the excess oil in
the housing cavity, gravitates toward the slinger 22 and is
absorbed by the latter before it can work its way out through the
coacting flanges and grooves through the slot 34 past the shaft 11.
Preferably, the oil absorber material used for the oil
slinger 22 is a sintered bronze material that is 30~-40% porous by
volume. The material has a bronze consistency of 92~ copper +
3% and 8% tin + 3%. The density of the material is 5.8 to 6.3
grams per cubic centimeter and the ultimate tensile strength is on
the order of 7000 psi.
Another material that could be utilized is a porous nylon
material having the same oil absorption characteristic as the sin-
tered bronze material, i.e. 30%-40~.
It should be understood that the figure of the drawing
illustrates the condition in which the oil slinger 22 is most
effective. That is, beneath the upper bearing of a vertically sup-
ported shaft. If the shaft 11 would be considered as horizontally
mountedj the oil slinger 22 would pick excess oil from whateverside of the cavity would be beneath the shaft extension 16. If
the mechanism utilizing the shaft 11 is operable in an inverted
position relative to that shown, the oil slinger 22 would probably
be non-functionaI since the excess oil would gather at the bearing
retainer 25 end. It should be understood that this end of the
housing 14 would be sealed by suitable rubber seals between the
housing 14, bearing retainer 25 and oil cap 26.
Further, if the shaft 11 projected through the housing
14 such as might occur if the shaft was centrally supported as well
as at its ends, an oil slinger 22 could be utilized at both sides
of the bearing 12 to prevent excess oil Elow from either end of
the housing.
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It is to be understood this invention is not limited
to the exact construction illustrated and described above, but
that various changes and modifications may be made without
departing from the spirit and scope of the invention as defined
by the following claims.
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