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Description  |
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BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to pumps and more particularly, but
not by way of limitation, to an improved submersible pump.
2. Description of the Prior Art
There is a market in this country and abroad for submersible pumps that are
efficient, lightweight, and inexpensive to manufacture. A pump
manufactured for submersion in process fluids must be protected from the
environment in which it operates, such as when it is submersed in water or
other corrosive fluids. Also, it should have good moisture stability.
Pumps that meet such service requirements are usually integrally
self-contained; that is, they are driven by enclosed motors sealed for
environmental protection.
In addition to these demanding requirements, there is the general problem
of making submersible pumps at reasonable cost. As usually found in
manufacturing processes, secondary operations involved in the making of
component parts, such as drilling and tapping holes, add large labor and
overhead economic burdens. Especially bothersome in the making of pumps
has been the alignment problems encountered during assembly operations. It
is not unusual during the assembly of pump components for trained
personnel to press, shave, strike, and otherwise adjust component parts so
as to obtain proper adjustment for each individual pump. This is not only
time consuming, it also introduces variations in pump operation due to the
component tolerances summing to give a wider span of operating
performance, thereby making prediction of pump performance more difficult.
Another problem encountered in submersible pumps is heat buildup due to the
enclosed motor as well as from the friction of bearing surfaces. This heat
may affect operating characteristics as well as shorten the effective
operating life of the pump and motor assembly. Therefore, the heat created
by the working parts of a submersible pump must be removed to give stable
and safe operation.
Another problem that presents itself with submersible pumps is that of
maintaining the exterior surfaces so that the pump retains its appearance.
In a consumer market, color often becomes a decisive factor and,
accordingly, submersible pumps must be designed with that in mind.
Generally speaking, painted surfaces have not always succeeded in such
service, and a good paint coating that will meet the rigorous test of
endurance is an expensive ingredient in the manufacture of submersible
pumps.
In addition to the above, there is a need for submersible pumps to be
constructed in a manner that assures complete electrical integrity; that
is, submersible pumps should be constructed with the advantages of the
best features of grounding and, preferably, constructed in compliance with
the double insulation principle. As to the latter, this refers to the
technique of insulating each part of the assembly from the electrical
motor such that the motor is completely isolated electrically and,
further, each potential conductor is insulated. This requirement for
submersible pumps has arisen from the experience of electrical shorting
whenever portions of electrical insulation are broken down due to wear,
fatigue or the like, whereupon electrical leakage has occurred. Of course,
in the case of submersible pumps, the danger presented from such
electrical leakage is increased by the possibility of conducting such
leakage through the submerging fluid.
SUMMARY OF INVENTION
The present invention is directed to a submersible pump that has a volume
chamber integrally formed with the housing and which extends into the
elastomeric housing. The chamber has a heat conducting volute wall and
interior wall, the latter having a fixed bearing molded into it so as to
establish a true axial alignment. A second self-adjusting bearing is
established by screw mounts distal to and in axial alignment with the
fixed bearing. A drive shaft extends through the two bearings.
An impeller is disposed within the volume chamber and is attached to the
drive shaft. An electric motor, enclosed in the housing, rotates the drive
shaft and, consequently, the impeller. The housing is hermetically sealed
and filled so as to be internally flooded with a dielectric, coolant fluid
which also serves as a lubricant.
Seal means sealingly engage the drive shaft at a point adjacent to the
interior wall of the volume chamber and effects a seal so as to prevent
the coolant fluid from entering the volume chamber, and thereby polluting
the process fluid being pumped.
Inlet and outlet ports are established relative to the volume chamber. An
inlet port feeds process fluid to the volume chamber at a point near the
axial center of the impeller, and the outlet port permits process fluid
withdrawal at a point removed from the inlet port as, for example,
tangentially to the volute wall.
Means is provided to substantially surround both the fixed bearing and the
adjusting bearing with coolant fluid so as to lubricate and cool all
bearing surfaces. Also, since the volume chamber walls are internally
extending to the housing, the walls are continuously contacted by the
coolant fluid. The volume chambmer thus provides a heat sink, the heat
generated from the pump and motor being transferred to the high velocity
process fluid being pumped.
An alternate embodiment of the present invention is provided wherein the
pump and motor assembly is insulated in a manner that isolates each
potential conductor, thereby guaranteeing the maintenance of electrical
integrity throughout the life of the assembly.
An object of the present invention is to provide a submersible pump and
motor assembly that provides improved component alignment.
Another object of the present invention is to provide a submersible pump
and motor assembly that requires minimum time and skill to assemble, but
that has precision quality of operation.
Another object of the present invention is to provide a submersible pump
that requires little or no secondary operations to manufacture with the
exception of the assembly thereof.
Another object of the present invention is to provide a submersible pump
and motor assembly that has a good surface appearance without the
requirement of external surface treatment, and which maintains such
appearance during its operating life.
Another object of the present invention is to provide a submersible pump
and motor assembly that will be available at a very low manufacturing cost
and require a minimum of maintenance, while achieving superior pump and
motor life.
Another object of the present invention is to provide an integral
submersible pump and motor assembly that utilizes pumped process fluid as
a heat sink for removing the heat generated by the motor and bearing
surfaces.
Another object of the present invention is to provide a submersible pump
and motor assembly that maximizes the heat transfer to the pumped process
fluid by effecting heat transfer to a high velocity liquid.
Another object of the present invention is to provide a submersible pump
that combines a material of construction and design that affords a
moldable assembly having high resistance to heat, chemical reaction and
moisture, while at the same time affording precision manufacture of
component parts which lead to improved pump and motor performance.
Another object of the present invention is to provide a submersible pump
and motor assembly that combines a material of construction and design
that affords an assembly having maximum electrical integrity such that all
component parts thereof are fully and independently insulated
electrically.
Other objects and advantages of the present invention will be apparent from
the following detailed description when read in conjunction with the
accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view of the pump and motor assembly of the present
invention.
FIG. 2 is a plan view of the pump and motor assembly of the present
invention, and has a partial cutaway view.
FIg. 3 is ia cross-sectional view taken at 3--3 of FIG. 2.
FIG. 4 is a perspective, exploded view of the pump assembly and housing
cover of the present invention.
FIG. 4A is a cross-sectional view of the volume chamber taken at 4A--4A in
FIG. 4.
FIG. 5 is a perspective, exploded view of the components contained within
the housing assembly of the present invention.
FIG. 6 is a cross-section taken at 6--6 in FIG. 4.
FIG. 7 is a cross-sectional view taken at 7--7 in FIG. 5.
FIG. 8 is a partial plan view of the housing cover with a partial cutaway
view showing the electric cord of the present invention.
FIG. 9 is an alternate embodiment of the present invention wherein the pump
and motor assembly has double insulation.
FIG. 10, similar to FIG. 7, shows in cross-section an alternate
construction of the bearing bracket as required for providing double
insulation for the pump and motor assembly of the present invention.
DESCRIPTION OF THE EMBODIMENT OF FIG. 1 THROUGH FIG. 8
Referring now to the drawings, and particularly to FIGS. 1 through 3, the
submersible pump and motor assembly of the present invention is generally
designated by the numeral 10, and comprises housing assembly 12, pump
assembly 14, and electric motor assembly 16.
The housing assembly 12 includes two sections: housing cover 18 and motor
cover 20. These covers are generally hollow rectangularly-shaped forms
that are designed to join together with interposinng O-ring 22
therebetween, and are then secured by the use of four screws 24, as best
seen in FIG. 3 and FIG. 5 the latter figure to be discussed below. The
covers 18 and 20 fit together to form a generally hollow, box-like housing
assembly 12 shown in FIG. 1.
The housing assembly 12 is molded of a material having a thermal
conductivity of at least 1.4 BTU-inch per hour per square foot per degree
Fahrenheit. The reason for this will become clearer below under the
discussion of heat transfer. A material having good heat transferability
has been found to be glass-filled nylon, which also possesses chemical,
moisture, and heat resistance properties that serve well in the pump and
motor assembly of the present invention. This material has been found to
have good dimensional stability and sharp resolution during molding so as
to provide practically burr-free edges and sharply-defined threads. This
eliminates all but an occasional secondary operation to prepare the molded
parts for use. However, this material is given only as an example of one
material suitable for molding the housing assembly 12 of the present
invention, it being recognized that there are a number of different
materials which will be required dependent upon the requirement for the
pump and motor assembly.
Continuing to describe the housing assembly 12, it should be noted that
posts 26 are provided as molded protrusions from planar surfaces 28 of
housing cover 18. The purpose for posts 26, as will be made clear below,
is to provide clearance to the pump assembly 14, which is flush to the
surface 28, when pump 10 is set upon posts 26. At the joining seam 30 of
housing assembly 12, there are mating flanges 32 necessitated by the
requirement of strength upon joinder of the housing cover 18 with the
motor 20. At each corner 17 of the housing cover 18 and molded as a part
thereof is an apertured boss 34. At each corner of motor cover 20 and
molded as a part thereof is a sleeve retainer 36 that has an aperture
therethrough aligning with the apertured boss 34. Screws 24 pass through
the sleeve retainers 36 and are self-tappingly received by the apertured
boss 34 to secure the housing assembly 12.
Provided on each of three sides of housing assembly 12 that form the
corners 17 are protruding ribs 38, except on wall 19 which will be
discussed below. The outer edges 40 for the ribs 38 along a given side of
housing assembly 12 are coplanar. This means, when the pump and motor
assembly 10 is set upon that side, all of the edges 40 of the protruding
ribs 38 will equally touch a planar surface so as to provide a stable
support for the present invention. As will become clear below with further
description of the pump and the motor assembly 10, protruding ribs need
not be provided for one side of the apparatus because of the conduits
leading to that side.
Referring to FIG. 5, the surface 42 of the motor cover 20 is a planar
surface for the purpose of permitting pump and motor assembly 10 to be set
thereon.
Turning now to a description of pump assembly 14, this can best be seen
from FIG. 4. Connected to the planar surface 28 of housing cover 18 is a
volume chamber 50 recessed or extending into the housing cover 18. For
manufacturing convenience, this chamber 50 is molded as an integral part
at the same time that the housing cover 18 is molded. The volume chamber
50 can best be described by referring to FIG. 4A which is a cross-section
of the chamber taken at 4A--4A in FIG. 4. Generally speaking, the volume
chamber 50 has the appearance of telescoping cylinders that are recessed
from surface 28 into housing cover 18. That is, chamber 50 is comprised of
a first cylinder chamber 52, the walls of which adjoin surface 28. Coaxial
therewith and connected to the first cylindrical chamber 52 is a second
cylindrical chamber 54, having a planar surface 56 which is connected to
the walls of the first cylindrical chamber 52. Next, there is a third
cylindrical chamber 58 coaxial with the first and second cylindrical
chambers and further extended therefrom and connected thereto by the
planar surface 60 which connects the peripheral edges of the second and
third cylindrical chambers. The third cylindrical chamber 58 is sealed at
its end opposite to the end attaching to planar surface 60 by a wall
member 62 that is normal to the third cylindrical chamber 58.
Returning to a description of the first cylindrical chamber 52 which is
connected to surface 28, adjoined thereto are two ear recesses 64, formed
by the walls of the first cylindrical chamber 52 extending therefrom and
the planar surface 56 which also extends so as to continuously meet the
walls of the first cylindrical chamber 52. This then gives the appearance
of an internally extending cylindrical chamber 52 from surface 28 having
the two recess ears 64 as shown in FIG. 4. There are two molded apertures
66 located through the planar surface 56 and projecting into the molded
wall of the second cylindrical chamber 52, as best may be seen in FIG. 4A.
These are established to receive self-threading screws, as will be
described later, and the plastic mold is designed to provide more bulk to
the external surface 68 so as to provide adequate material volume around
these apertures 66 which extend for a distance and are bottomed as shown
in FIG. 4A.
The wall 70 of the second cylindrical chamber 54 forms the volute for the
volume chamber 50. The planar surface 60, the third cylindrical chamber
58, and the end member 62 form an interior wall which seals the second
cylindrical chamber 54 on one end. The end member 62 has an aperture 72
formed about the outer edge 73 of the flanged bearing 74. This bearing 74
may be established at the time of molding; that is, it is set in place
within the mold cavity that forms volume chamber 50 together with housing
cover 18 and is therefore anchored and permanently adjoined to end member
62. In the embodiment shown, this bearing 74 is pressed into aperture 72
following the molding process of housing cover 18 and volume chamber 50,
so as to maintain the axial alignment coincident with the axial centers of
the above-described first, second, and third cylindrical chambers. The
bearing 74 has an aperture 76 therethrough which establishes the alignment
of the drive shaft as will be made clear below, and it has therefore been
found that the internal diameter of aperture 76 should be maintained
within plus or minus 5/10,000ths of an inch. While there are a number of
materials that may be used to fabricate bearing 74, it has been found that
self-lubricating sintered bronze provides an adequate material for this
use.
The end member 62 has four apertures 78 equally spaced about bearing 74,
providing fluid communication between the third cylindrical chamber 58 and
the interior of housing cover 18.
Turning now to a description of the component parts that complete the pump
assembly 14, attention is directed to the exploded view of FIG. 4. A
description of these parts will first be given, followed by a discussion
of how they are assembled into volume chamber 50. Commencing with the seal
80, this is a shaft seal which is commonly known and which is comprised of
a steel ring member 82 with a rubber-like transverse member 84 attached
thereto and which necks down to form an expandable seal annulus 86. A
suitable material for the transverse member 84 is Viton, a fluoroelastomer
made by E. I. du Pont de Nemours & Company, Wilmington, Delaware. The
circular ring 82 is sized to pressingly fit within the third cylindrical
chamber 58 of volume chamber 50.
The impeller 90 has a cylindrical post 92 that has an aperture 94
longitudinally therethrough. Attached to the outer edges of post 92 are
four laterally extending blades 96. The impeller 90 is sized so as to
rotatingly occupy the second cylindrical chamber 54 of volume chamber 50,
such that the impeller blades are displaced from the volute wall 70 by
approximately 1/16th of an inch when the impeller is axially aligned with
the center of the second cylindrical chamber 54.
The volute plate 100, shown in FIGS. 4 and 6, is a wafer-shaped plate that
fits into the first cylindrical chamber 52 and has a lip portion 102 which
is shaped to project into the second cylindrical chamber 54 for a distance
of approximately 1/16th of an inch, or to a distance that partially fills
the second cylindrical chamber 54 but which avoids contact with the
impeller 90. The volute plate 100 has ears 104 that are fittingly received
by the recessed ears 64, and which have apertures 106 that matingly align
with the apertures 66 that are located on planar surface 56. Located at
the center of volute plate 100 is an aperture 108 that serves as the inlet
port to the pump assembly 14. O-ring 110 is sized to fit around the lip
102 but will not enter the opening of the second cylindrical chamber 54,
thus providing the means for a seal between volute plate 100 and the
surface 56.
Next in the exploded view of FIG. 4 is intake screen 112, shaped similar to
the volute plate 100. That is, the intake screen 112 has a cylindrical
portion 114 and ear portions 116 protruding therefrom that are shaped so
as to be fittingly received by the first cylindrical chamber 52 and the
recessed ears 64 thereof, and when so placed, the flat surface 118 of
intake screen 112 will be approximately flush or slightly recessed from
the surface 28 of housing cover 18. Located through the ears 116 are
apertures 120 that are aligned with apertures 106 of the volute plate and
apertures 66 in surface 56. Surrounding apertures 120 are counterbore
recesses 122 in the surface 114, sized to receive the head of the screw
124. As shown in FIG. 4, intake screen 112 has a plurality of openings 126
therethrough that collectively form a grid 128 which serves as a screen
for the pump assembly 14.
To complete the description of the parts shown in exploded view in FIG. 4,
attention is now directed to the upper lefthand corner of housing cover 18
as is drawn therein. The housing cover 18 has a recessed threaded aperture
130 which is surrounded by a relief recess 132. Oil plug 134 is an
elastomeric nut having a threaded portion 136 that is threadingly
engageable with the aperture 130. An O-ring 140 is passingly received by
the threaded portion 136 and abuts on the underside of the head 138 of oil
plug 134. The head 140 is clearingly received by the relief recess 132 and
is sized so that the head 140 will be flush to or slightly recessed from
surface 28 when oil plug 134 is tightly secured in aperture 130.
To this point in the discussion of the pump and motor assembly of the
present invention, progress has been made to the point of describing those
components shown in the exploded view of FIG. 4. A discussion of these
components in assembled condition will be undertaken following a
discussion along the same lines as above to describe the component
elements of the motor assembly as shown in the exploded view of FIG. 5.
This will permit a more complete discussion of the assembly once the
components are completely identified.
Turning now to FIG. 5, shown therein is an exploded view of the components
that make up the motor assembly 16 together with the housing cover 18 and
the motor cover 20. Housing cover 18 has four mounting posts designated by
the numerals 150 and 152. Each of these posts 150, 152 has a molded
aperture 154 that extends longitudinally to and is blind ended in its
respective post. Two of the mounting posts, 150, have a projecting sleeve
156 extending therefrom.
The drive shaft 160 has an impeller end 162 and a support end 166. The
impeller end 162 has a diameter that is bearingly supported by the fixed
bearing 74 located in end 62 of the third cylindrical chamber 58 of the
volume chamber 50. Thrust washer 168 is made of steel and has an aperture
170 that is passingly received by the impeller end 162 of the drive shaft
160.
Interposed between the impeller end portion 162 and the support end 166 and
attached to the drive shaft 160 is rotor 172. The rotor 172 need not be
described in detail, as information thereof is readily available and will
vary in construction according to the particular motor assembly selected.
It is sufficient herein to state that the rotor 172 is receivable by the
stator assembly shown as 174 in FIG. 5. For the present invention, a
typical electrical rating of a selected motor assembly has a rotor
approximately one and 1/8 inch in diameter and approximately 9/10 of an
inch in length. The stack height of the stator assembly would be
approximately 3/4 of an inch and the motor assembly would be rated at
one/one hundredth horse power, 2900 RPM, 42 watts, 7/10 amps on 110 volt
service. While this electrical rating is given as an example of typical
motor assemblies, the present invention is not limited to the dimensions
selected for the pump or motor assembly, as it contemplates adaptability
in a wide range of pump and motor assembly sizes. Thus stated, it
nonetheless will be necessary for purposes of disclosure herein to
describe the assembly of a preferred embodiment and, for that purpose, the
description continues.
Stator assembly 174 has a stack 176 with apertures therethrough of 178 and
180. The apertures 178 align with the apertures 154 in the mounting post
150 and are sized to receive the sleeves 156 protruding therefrom. The
sleeves 156, therefore, serve as locating dowel surfaces as the stator
assembly 174 is positioned on the mounting posts 150 and 152.
The apertures 180 align with the apertures 154 in the mounting posts 152
when the stator assembly 174 is assembled to the mounting posts 150 and
152. The screw position of screws 182 are clearingly received through
apertures 180 and are self-tapping to seat in apertures 154 of the
mounting posts 152. Lock washers 184 are interposed between the screws 182
and the stator assembly 174.
The support end 166, as will be made clear below, is bearingly receivable
by the bearing bracket 190 shown in FIG. 5 and in cross-section in FIG. 7.
The bearing bracket 190 has a bracket portion 192 that is shaped with legs
194 so as to mount on the stator assembly 174 a clearing distance
therefrom. Each of the legs 194 has an aperture 196 and sleeve 198. The
apertures 196 are spaced so as to align with the apertures 178 of stator
assembly 174 and the sleeves 198 are dimensioned with diameters receivable
by apertures 178, thereby forming locating dowel surfaces on the bearing
bracket 190 for relative positioning thereof with the stator assembly 174.
The bearing bracket 190 has an axially alignable bearing 200 in the
approximate center thereof. The bearing 200 is aligned next to an aperture
202 in the bearing bracket 190, but is restrained by its size from passing
therethrough. The bearing 200 has an aperture 203 that has a diameter to
bearingly receive support end 166 of drive shaft 160. As for bearing 200,
it is made of material of the type recommended for the fixed bearing 74 in
volume chamber 50. At the end of bearing 200 that is opposite to aperture
202, bearing 200 is held by a flexible assembly 204 that is connected to
the bracket 192. This permits the axial center 206 to be angularly
displaced with the flexure of the assembly 204. Such bearing brackets as
described for bearing bracket 190 are commercially available, and the
discussion herein has been given for a disclosure of the principle of the
operation of such bearings.
To complete the discussion of the components shown in the exploded view of
FIG. 5, mention here is made of the thrust washer 210 that has an aperture
212 pressingly receivable by the support end 166 of drive shaft 160. The
purpose of thrust washer 210 is to adjust the end play of the drive shaft
160, and the thrust washer 210 is therefore usually made of an elastomeric
material such as nylon. Also, mention is made of the retaining screws 182,
equipped with lock washers 184, which pass through the apertures 196, the
apertures 178, and self-tap the apertures 154 in the mounting posts 150 of
housing cover 18.
Turning once more to FIG. 2, it can be seen by the partial cutaway view
that the necessary outlet for the pump assembly 14 is provided by outlet
port 220 which is a canal integrally molded with housing cover 18, the
canal tangentially joining and entering volume chamber 50 through threaded
nipple 222 extending from wall 19 and integrally formed with the housing
cover 18.
Located near a corner of the housing assembly 12 and adjoining wall 19 is a
conduit inlet 224 that has threaded aperture 226 communicating with the
interior of housing assembly 12. This may best be seen in the partial
cutaway view of FIG. 8. The aperture 226 is partially blocked at its
inward end by shoulder 228. Shown in FIG. 8 is a portion of a molded
electric cord 230 which has a molded plug 232 having a cylindrical portion
234 extensible through aperture 226 and a portion 236 that abuts against
and is restrained by shoulder 228. Washer 238 is receivable by aperture
226 and abuts against the plug portion 236. Hollow, threaded plug 240 is
threadingly receivable in aperture 226. The connections 242 are
electrically connectable to the stator assembly 174.
Turning now to the assembly details of the present invention, the first
step is to insert and securedly attach the molded electric cord 230 into
inlet conduit 224 as shown in FIG. 8, and as described above. The cord 230
is then electrically connected to stator assembly 174. Next, referring to
FIG. 5, the stator assembly 174 is mounted onto mounting posts 150, 152,
and it is secured thereto at posts 152 by screws 182 placed through lock
washers 184 and apertures 180. As the screws 182 are tightened into
apertures 154 of posts 152, the screws self-tap these apertures. Next,
drive shaft 160, with rotor 172, thrust washer 168, and thrust washer 210
affixed thereto, is put into place by passing impeller end 162 through
apertures 76 of bearing 74 so that thrust washer 168 abuts against bearing
74. The thrust washer 168 is located on drive shaft 160 so that the rotor
172 is correctly positioned relative to stator assembly 174. This can also
be observed by referring to FIG. 3. The bearing bracket 190 is mounted to
stator assembly 174 with the support end 166 passing through the aperture
203 of bearing 200. The screws 182 are placed through the lock washers
184, apertures 196 of brac | | |
