Note: Descriptions are shown in the official language in which they were submitted.
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SPECIFICATION
This invention relates to bearings, More particularly,
this invention is a new bearing including a new bearing seal,
Bearing seals are meant to exclude contamination from
entering the bearing and to retain lubricant in the bearing
for the decrease of friction between the moving bearing
components. The seal is normally fixed to one part such
as a race or cage and slides or rubs against another part
of the bearing such as race or shaft. Seals are used in bot~
rotary and linear service, continuous or intermittent or
oscillatory~ Lip seals, face seals, packings and "O-ringsn
are among those items which lie in the general category of
"bearing seals".
Unless the sealing lip or contact rubbing surface is
lubricated in some fashion there is quite a bit of friction
between the seal and the part againstwhich it rubs. Thia
friction results directly in abrasion of the seal and the
mating slide surface. Eventually this harms the sealing
function. It also results in the generation of excessive
heat which may be detrimental to the seal itself, again
harming the sealing function, to the other components of
the bearing, and to the lubricant contained in the bearing.
Any and all damage is liable to decrease bearing life.
Therefore, many kinds of seals have been formulated which
are meant to help introduce a slight amount of lubricant
between the seal lip or other rubbing contact surface and
the sliding mating surface to reduce or eliminate this
particular rubbing friction while still allowing the seal
to perform its functions of retaining lubricant and ex-
cluding contaminants.
;
In some cases, the lubricant does not draw in under the ;
seal lip. In other cases there is no liquid lubricant or
grease in the bearing which can be drawn in under the seaLed
lip to lubricate it. Some bearings are run dry and without
any lubricant whatsoever. Other bearings are run with a dry,
low-friction solid lubricant which may, for example, be
dispersed in a plastic resin to form a bearing surface. For
example, some sealed ball bushings may have such a dry, low-
friction bearing surface which lies against and slides
against a mating steel bearing surface. The seal generally
does not rub against the low-friction surface, instead, it
rubs against the mating steel bearing surface which may be
simply a hardened steel or it may be a steel which has been
plated with chromium or nickel or cadmium. This dry rubbing
results in the aforementioned high friction, with resulting
high abrasion and possibly high heat generation. The bearing
life is thus markedly reduced from the service life it would
have without that friction.
According to a broad aspect o the present invention ;
there is provided a seal located to seal the space between
a first and a second race member provided in a bearing.
First race member is spaced from the second race member and
movable relative to each other with the seal located in the
space therebetween. The seal includes a single member
consisting of a plurality of frangible microcapsules dispersed
within a seal material body. A lubricant is held in the
microcapsules for release from worn and broken microcapsules
as the seal material body becomes worn and for distribution
at the rubbing contact surface of'the seal material body after
release.
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~(~ According to a further aspect, my new bearing
comprises first and second bearing race members movable ;
relative to each other and with one or more seals located
to seal the space between the members. One or each bearing
race may be a machine element, as for example a shaft. The
seal includes a seal body, preferably elastomeric, holding
individual minute lubricating particles which include a
lubricant encapsulated in an encapsulating wall. The latter
are known as lubricant filled microcapsules. The micro- `
capsules may be dispersed throughout the seal body, or may
be dispersed in selected sections of the seal body,
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or may be coated on and bonded to specified surfac~s of he
seal. A stiffening member, possibly of metal or hard pl~stic~,
may be incorporated in or bonde~ to or mechanicall~ fas~^ned
to the seal body. ~ -
The new seal incluaes a plurality of frangible micro-
capsules constructed to be worn through by abrasion and/or ta
be broken upon the application of pressure on the capsules~
A lubricant is held in the microcapsules for exposure and
release from the individual broken microcapsules and for
distribution between mating rubbing contact surfaces of seal
and race after release. The seal body material su?ports
the microcapsules. There may be tens of thousands of micro-
capsules incorporated in one seal.
The lubricant is preferably a liquid lubricant, such
as a petroleum oil, but may be a solid dry lubricant. The
friction which is generated between the seal and ~he mating
slide surface will wear through the walls of the first
microcapsules as the seal lip slide surface, exposing and
releasing minute amounts of the lubricant to coat the sliding
contact area of seal and race. This lubricant reduces the
friction at the seal lip slide surface. As the bearing
continues to operate, the exposed lubricant is ~radually
dissipated. As the lubricant dissipates there is again a
slight increase in friction and the walls of other micro-
capsules gradually are worn through, releasing more lubri-
cant as needed to again decrease the friction. Thus, we
have a gradual lubricant release throughout the operating
life of the seal. Because of the lubricant there is little
abrasion of the bearlng surface where it contacts the sealin~
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lipD The abrasion of the sealing lip itself is reduced.
There is little frictional heat generated and thus no heat
damage to the bearing or seal lubricant from that cause.
The life of both seal and bearing is greatly extended.
If a dry lubricant is used rather ~han c~r in conjuncticn
with a liquid lubricant, we may use a microencapsulated orgz~ic
or inorganic dry lubricant such as polytetrafluoroethylene or
molybdenum disulfide. As the microcapsules of the seal
are worn through, the dry lubricant is exposed to the bearins
slidesurface, and smears or coats the surface contacted.
Here again, we have a decrease in friction between the seal
and the bearing slide surface thus decreasing the abrasion
to both the seal and the bearing surface and decreasing
the generation of heat. Again, the exposure of the fresh
solid lubricant to the rubbing surfaces is relatively stead
and uniorm over a long period of bearing operation.
Two or more different microencapsulated lubricants may
be placed in any one seal. There may be multiple liquids or
multiple solids or any combination of liquids and solids,
each in its own microcapsules. Thus I may have a co~binatic~
o lubricants for the seal which will allow the seal to
operate properly under a much wider range of chemical,
thermal, and mechanical conditions than would a seal with
a single lubricant. I may also use a combination of micro-
encapsulated lubricant and unencapsulated solid lubricant
such as polytetrafluoroethylene flock in the same seal. The
microcapsules might have solid continuous walls such as
shown in U. S. Patents 2,800,458; 3,516,g41; and 3,993,831.
The solid continuous walls are generally impervious to the
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lubxicant and prevent all passage of the lubricant until
~he wall is worn away or broken away. If desirable, ~e
might instead or in addition also have microcapsules which
ha~e tiny passageways through the walls through which ~he
liquid lubrican-t can gradually come out even without wearing
away or breaking away the major thickness of the capsule `
wall. Microcapsules with tiny passageways are described
in U. S. Patent 3,985,840.
The elastomeric material of the seal body may be very
flexible, such as a rubber or a flexible urethane. It als~
can be a more rigid material of either the thermoplastic
or the thermoset resin variety.
Although normally the microencapsulated lubricant
would be dispersed throughout the seal body material, it ~ ~;
is also practical to disperse it only in a localized sect~on
of the seal such as the fIexible lip of a lip seal or ~ihe
rubbing face area of a face seal or the scraping lips of
shaft packing. Dual molding and dual extrusion are two
well-known methods of accomplishing this. Separate parts,
at least one of them containing the microencapsulated
lubricant, may also be fastened together by any of the wel~-
known methods which include at least chemical and mechanic~l
bonding and welding.
It may be that for some bearing applications only a
thin layer of the microencap$ulated lubricants is needed
and we do not need the micxoencapsulated lubricants dis-
tributed throughout the entire seal body. In such case,
a coat of a microencapsulated lubricant may be coated on
one surface of the body. The microencapsulated ]ubricant
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will be rubbed away as the surface of the microencapsulated
lubricant coat rubs against the mating bearing part.
My new bearing seal may also take the form of the
typical"O-rin~'with round or other shaped cross-~ections
with the microencapsulated lubricant distributed throughout,
or with the microencapsulated lubricant coated onto one or
more of the surfaces or onto one or more areas of the
surface. A non-round sealing configuration is shown in
U. S. Patent 3,472,523.
