A desiccant device for preventing rotor bearings from rusting during
nonuse is described which removes moisture from the air supplied
to such bearings. The air supplied to the bearings is first transmitted
through the desiccant device by connecting such device to the lubrication
fittings of such bearings. The bearing breather desiccant device
can be connected to electrical motors, pumps, gear reducers or other
equipment having rotor bearing means which tend to rust during storage
or other periods of nonuse when the lubricant drains away from the
surface of such bearing. The desiccant can include a moisture indicator
which changes color to indicate the amount of moisture absorbed
by the desiccant so that the desiccant device can be replaced before
it is no longer effective. The moisture indicator is viewed through
a light transparent plastic bag containing such desiccant.
1. Rotor bearing apparatus, including bearing breather, comprising:
rotor means mounted on bearings;
housing means containing at least a portion of said rotor means
including the rotor bearings and having a bearing lubrication passage
for said bearings;
drying means containing a desiccant material for removing moisture
from air transmitted therethrough from an inlet to an outlet of
the drying means;
inlet means for transmitting air into the inlet of the drying means
and through the desiccant to provide a source of dry air at the
outlet of said drying means; and
output means for transmitting said dry air from the outlet of said
drying means through said lubrication passage to the rotor bearings
to supply said dry air to said bearings.
2. Apparatus in accordance with claim 1 in which the drying means
includes a container and the desiccant material is desiccant particles
provided within said container whose wall is impervious to air except
for the inlet and outlet of the drying means, and having an air
inlet passage through the wall of said container to provide said
3. Apparatus in accordance with claim 2 in which the output means
includes at least one conduit connected at its input to the interior
of the container so that said conduit input is separated by said
desiccant material from said air inlet passage and connected at
its output to said lubrication passage.
4. Apparatus in accordance with claim 3 in which said at least
one conduit is a flexible tube and the container is sealed so that
only dry air flows through the tube to the bearings.
5. Apparatus in accordance with claim 4 in which the inlet means
transmits said air at atmospheric pressure through said air inlet
passage which is separate from said at least one conduit, said container
comprising a flexible plastic bag while the air inlet passage and
the flexible tube extend through a plug member covering an opening
in said bag.
6. Apparatus in accordance with claim 1 in which the rotor means
is the shaft of an electrical motor and the motor is sealed so that
air is supplied to the bearings only through the drying means.
7. Apparatus in accordance with claim 1 in which the drying means
contains a moisture indicator which changes color according to the
amount of moisture absorbed by the desiccant material.
8. Apparatus in accordance with claim 7 in which the desiccant
material is provided in a container at least a portion of which
is light transparent to enable observation of the indicator.
9. Apparatus in accordance with claim 8 in which the container
is a bag of transparent plastic material.
10. Apparatus in accordance with claim 9 in which the output means
includes at least one tube extending into the bag so that its air
input end is separated by the desiccant material from said air inlet
for said bag.
11. Apparatus in accordance with claim 10 in which the air inlet
is provided as a passage through a plug member covering an opening
in the bottom of the bag and said at least one tube extends through
a hole in said plug member spaced from said air inlet passage.
12. Apparatus in accordance with claim 11 in which the top end
of said at least one tube and the air inlet passage are provided
with a filter material pervious to air and impervious to the desiccant
13. A bearing breather desiccant device, comprising:
an air tight container having an air inlet and at least one air
outlet spaced from said air inlet;
desiccant material provided in said container between said air
inlet and said air outlet, for removing moisture from air transmitted
inlet means for transmitting atmospheric air to said container
into said air inlet and through the desiccant material to said air
outlet to provide a source of dry air;
an outlet tube connected at one end to said air outlet;
support means for supporting said container on the exterior of
a housing containing a rotor bearing having a lubrication fitting;
connection means separate from said support means, for connecting
the other end of said outlet tube to the lubrication fitting of
said rotor bearing.
14. A desiccant device in accordance with claim 13 in which the
container is a transparent plastic bag and a moisture indicator
is provided in said bag with the desiccant material to indicate
the moisture content of said desiccant by color changes of said
15. A desiccant device in accordance with claim 13 in which the
connection means is a threaded connector.
16. A desiccant device in accordance with claim 13 in which the
container is a flexible plastic bag sealed to a plug member, said
air inlet is provided by an inlet passage through said plug member,
said at least one air outlet is an outlet opening through said plug
member spaced from said inlet passage and said outlet tube extends
through said outlet opening into said bag so that its one end is
separated from the inlet passage by said desiccant material.
BACKGROUND OF THE INVENTION
The subject matter of the present invention relates generally to
a desiccant device for removing moisture from air supplied to the
rotor bearings of motors, pumps, gear reducers and the like, to
prevent such bearings from rusting. In particular, the preferred
embodiment of such bearing breather desiccant device is provided
with one or more outlet tubes which are connected to the lubrication
fittings of the equipment containing the bearings so that any air
supplied to such bearings must be transmitted through the desiccant.
The present invention is especially useful in preventing the rotor
bearings of electrical motors from rusting.
Previously, electrical motors, pumps, gear reducers and other apparatus
having rotor bearings have suffered from the problem of bearing
rust during storage or other periods of nonuse. This is caused by
moisture condensing from the air onto the bearings when the temperature
of the bearings falls below the dew point. Previously electrical
heaters have been installed around the bearings to keep their temperatures
above the dew point. Another solution has been to hermetically seal
the equipment to prevent moisture laden air from reaching the bearings.
However, both of these solutions are extremely expensive and cannot
be employed on smaller motors, pumps and other relatively inexpensive
equipment. Therefore, it has previously been the practice in these
cases for a maintenance person to manually rotate the rotor shafts
of the equipment every week in order to recoat the bearings with
lubricant. Unfortunately this is not effective for the most part
especially when the equipment is stored in direct sunlight or in
a shed which is heated by the sun, because such heat causes the
grease or oil used as a lubricant to drain away very quickly from
the recoated bearings, often within one day. As a result, moisture
condenses on the nonlubricated surfaces of the bearings, and rusting
results before the shaft can be rotated manually again.
The bearing breather desiccant device of the present invention
will reduce the moisture in the air supplied to the bearings and
thereby prevent such bearings from rusting. All openings other than
the lubrication fittings to which the tubes of the desiccant device
are connected must be sealed to force the equipment to breathe air
through the desiccant device. It should be noted that during nonuse
equipment bearings breathe as a result of expansion and contraction
of the air due to changes in the ambient temperature. The invention
has the added advantage of being relatively inexpensive and easy
to install on the equipment being protected. Of course, the desiccant
device must be replaced when it has absorbed so much moisture that
it no longer operates efficiently. This is indicated by a change
in color of the desiccant which can be viewed through the wall of
a transparent plastic bag containing such desiccant. While the desiccant
device of the present invention greatly reduces the amount of moisture
which can condense on the bearings, for added protection the rotor
shafts of the motors and other equipment should still be manually
rotated at regular intervals.
Previously, desiccant devices have been used in the lines of refrigerant
systems to remove moisture from the refrigerant fluid, as shown
in U.S. Pat. No. 3734296 of Proctor et al and U.S. Pat. No. 3979292
of McClive. It has been suggested to use a chemical moisture indicator
in the desiccant device of such refrigeration systems, which changes
color to visually indicate the amount of moisture absorbed, as discussed
in U.S. Pat. No. 3246758 of Wagner. However, none of these patents
suggest that a desiccant device can be used to prevent the rotor
bearings of motors, pumps, gear reducers and like equipment from
rusting by connecting air outlet tubes of the device to the lubrication
fittings of the bearings and sealing all other air openings to the
bearings in the manner of the present invention.
SUMMARY OF THE INVENTION
It is one object of the present invention to provide a bearing
breather desiccant device for preventing the rotor bearings of motors,
pumps, gear reducers and other equipment from rusting during nonuse
by removing moisture from the air supplied to such bearings.
Another object of the invention is to provide such a bearing breather
desiccant device which is inexpensive and easy to install.
A further object of the invention is to provide such a bearing
breather desiccant device which can be employed on various sizes
of equipment containing the bearings to be protected.
An additional object of the invention is to provide such a bearing
breather desiccant device which includes air outlet tubes that are
connected to the lubrication fittings of the bearings.
Still another object of the invention is to provide such a bearing
breather desiccant device with a moisture indicator for the desiccant
which changes color according to the amount of moisture absorbed
by the desiccant and visually indicates this when viewed through
a transparent container for such desiccant.
Other objects and advantages of the present invention will be apparent
from the following description of a preferred embodiment thereof
and from the attached drawings of which:
FIG. 1 is an elevation view showing the bearing breather desiccant
device of the invention connected to an electrical motor;
FIG. 2 is an enlarged view of portions of FIG. 1 with parts broken
away for clarity; and
FIG. 3 is a horizontal sectional view taken along the line 3--3
of FIG. 2.
DESCRIPTION OF PREFERRED EMBODIMENT
As shown in FIG. 1 a bearing breather desiccant device 10 forming
an air drying means in accordance with the present invention is
provided with a pair of flexible air outlet tubes 12 and 14 of polyethylene
plastic which are connected from the outlets of the device to lubrication
fittings 16 and 18 of an electrical motor 20 or other rotor bearing
means. The desiccant device 10 includes a container 22 which like
the tubes may be a transparent plastic bag made of polyethylene
or other suitable synthetic plastic. The bas is provided with a
hanger eyelet 24 at its upper end to which a loop of string 26 is
attached for supporting the device on the motor by looping the string
over a motor carrying ring 28 attached to such motor.
As shown in FIGS. 2 and 3 the outlet tubes 12 and 14 and an air
inlet passage 30 all extend through a plug member 32 of resilient
rubber, or suitable synthetic plastic, to support the outlet tubes
in a fixed position within the plastic bag 22 as well as to form
air tight seals with such tubes and the bag. The upper ends 34 and
36 of tubes 12 and 14 respectively are spaced from the upper end
38 of the inlet passage 30 so that air transmitted through such
inlet passage must pass through desiccant particles 40 contained
within bag 22 before passing through outlet tubes 12 and 14 to rotor
bearings 42 in the motor 20. As a result, any moisture in the air
supplied to the bearings through the tubes is removed before such
air is transmitted to the bearings.
The plug member 32 is a solid circular cylindrical member inserted
into an opening in the bottom of the bag 22. The bag is fastened
to the plug member by a cord or metal wire 44 wrapped around the
bottom of the bag and tied or tightened to form an air tight seal
between the bag and the plug member. A quantity of filter material
46 such as fiberglass wool, is inserted into the air inlet passage
30 to prevent the desiccant particles 40 from falling out of the
bag through such inlet passage. Similarly other inserts of fiberglass
wool 48 and 50 are provided in the upper ends of the outlet passages
12 and 14 to prevent desiccant particles from entering such tubes
and finding their way into the lubrication fittings of the motor.
Of course the fiberglass wool inserts are sufficiently porous to
The plastic bag 22 is filled with desiccant particles through an
opening in the upper end of such bag adjacent to eyelet 24. After
filling, the upper opening is closed by a heat seal 52 during manufacture
of the device.
The lubrication fittings 16 and 18 are each threaded into a fitting
receptacle opening 54 at one end of a lubrication passage 56 extending
through the motor housing to bearing 42. While any suitable rotor
bearing may be employed, it is normally a ball bearing which is
held in place by a closure ring 58 secured by bolts 60 to the housing.
The bearing includes a plurality of balls 61 an inner race 62 fixed
to motor shaft 64 or other rotor, and an outer race 63 fixed to
the motor housing. A pair of resilient seals 66 and 68 of rubber
or plastic are provided between the shaft 64 and the motor housing
20 and between such shaft and the bearing closure member 58 to seal
the bearing. However, a layer of grease should also be provided
on the shaft to prevent air from leaking through seals 66 and 68.
In addition all other air holes to the bearings including drain
holes should be hermetically sealed with tape. Thus any air supplied
to the bearings 42 must pass through an output means including two
passages 56 which are connected by outlet tubes 12 and 14 to the
desiccant device 10 for connecting such bearings to the outlets
of such desiccant device. This means that only dry air from which
substantially all moisture has been removed is supplied to the bearing.
As a result the condensation of moisture on the bearing is greatly
reduced and rusting of the bearing is thereby prevented. Of course
it is not possible to eliminate all moisture from the air, and there
may be some air leakage past seals 66 68 and other openings. Nevertheless,
the bearing breather desiccant device of the present invention effectively
prevents rusting of the bearings and greatly increases the useful
shelf life of the motor, pump, gear reducer or other apparatus to
which it is connected.
It should be noted that the lubrication fittings 16 and 18 may
have to be replaced by different fittings in order to fit within
the inner diameter of the outlet tubes 12 and 14. Therefore, when
describing the outlet tubes as being connected to the lubrication
fittings of the motor, the term "lubrication fittings"
actually refers to the fitting receptacle openings 54. Thus, in
most cases the metal lubrication fittings are removed and replaced
by plastic fittings 16 and 18 to which the tubes are attached by
slipping such tubes over the stems 70 of such fittings.
The desiccant particles 40 contained within the bag 22 may be made
of silica gel or any other suitable desiccant material including
the type which contains a moisture indicator that changes color
depending upon the amount of moisture absorbed in such desiccant.
Another suitable desiccant is phosphorous pentoxide which acts by
absorption in chemically reacting with the water, as opposed to
the physical adsorption of water by silica gel. One type of desiccant
and moisture indicator suitable for this purpose is shown in U.S.
Pat. No. 3246758. In this patent the moisture indicator is provided
as a separate paper disc impregnated with the indicator chemical
which is adhered to the inner surface of the container for the desiccant.
However, it is also possible to provide the indicator material mixed
with the desiccant material.
It will be obvious to those having ordinary skill in the art that
many changes may be made in the details of the above-described preferred
embodiment of the present invention, without departing from the
spirit of the invention. Therefore the scope of the present invention
should only be determined by the following claims.