U.S. patent number 3,612,716 [Application Number 05/046,268] was granted by the patent office on 1971-10-12 for multistage centrifugal pump.
This patent grant is currently assigned to Red Jacket Manufacturing Company. Invention is credited to Elmer M. Deters.
United States Patent |
3,612,716 |
Deters |
October 12, 1971 |
MULTISTAGE CENTRIFUGAL PUMP
Abstract
Several embodiments of pumps are shown which are advantageous in
pumping liquids containing abrasives. FIGS. 1-4 show a centrifugal
pump with floating stages. Each stage has a rubber journal and a
stainless steel bushing which provide a radial bearing as well as a
seal between the impeller chamber and diffuser passages. The other
embodiments show other forms of the bearing and journal members
applied to a stacked (nonfloating) impeller type of centrifugal
pump. In FIGS. 7 and 8, one of the members is tapered to allow the
motor to operate more easily in liquids containing abrasives.
Inventors: |
Deters; Elmer M. (Muscatine,
IA) |
Assignee: |
Red Jacket Manufacturing
Company (Davenport, IA)
|
Family
ID: |
21942527 |
Appl.
No.: |
05/046,268 |
Filed: |
June 15, 1970 |
Current U.S.
Class: |
415/140; 415/141;
415/199.3; 415/901 |
Current CPC
Class: |
F04D
13/10 (20130101); Y10S 415/901 (20130101) |
Current International
Class: |
F04D
13/10 (20060101); F04D 13/06 (20060101); F04d
001/00 (); F04d 001/06 () |
Field of
Search: |
;415/199,501,198,110,111,112,113,116,17A,169,171,172,173,174,104,105,106,140 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
|
|
|
|
|
|
|
1,110,660 |
|
Apr 1968 |
|
GB |
|
1,095,610 |
|
Dec 1958 |
|
DT |
|
Primary Examiner: Raduazo; Henry F.
Claims
I claim:
1. In a multistage diffuser-type centrifugal pump for pumping
liquid from a main pump inlet to a main pump outlet and including:
a rotatable drive shaft; a plurality of pump impellers each having
a hub engaged with the drive shaft for rotation therewith, a rear
wall extending outwardly from the hub, a central opening, a front
wall extending outwardly from the central opening, and impeller
passages extending between the front and rear walls toward the
outer periphery of the impeller; and a nonrotatable pump casing
surrounding said impellers and including a plurality of walls each
spaced axially forwardly of the front wall of a respective
impeller, a plurality of nonrotatable diffuser walls each spaced
axially rearwardly of the rear wall of a respective impeller to
define a plurality of impeller chambers, and means defining a
plurality of diffuser passages for transferring liquid from the
periphery of each impeller chamber to the rear side of the
respective diffuser wall and to the inlet opening of the impeller
of a succeeding pump stage; the improvement comprising: each pump
stage having an annular rubber member and an annular stainless
steel member engaged with each other; means for mounting one of the
members rearwardly of the rear wall of the impeller for rotation
with the drive shaft and impeller; means for mounting the other
member on the nonrotatable diffuser wall and in sealing engagement
with the one member to provide a seal between the impeller chamber
and the diffuser passages, to reduce backflow of liquid and to
provide a radial bearing for the drive shaft at each pump
stage.
2. A multistage diffuser-type centrifugal pump as set forth in
claim 1 wherein the rubber member is mounted on the rotatable drive
shaft, and the stainless steel member is mounted on the
nonrotatable diffuser wall.
3. A multistage diffuser-type centrifugal pump as set forth in
claim 2 wherein the drive shaft is externally splined; the rubber
member is internally splined, mounted directly on the drive shaft
and spaced from at least one adjacent impeller hub; and the
impellers are dimensioned in relation to the impeller chambers to
permit limited independent float of the impellers axially within
their respective chambers.
4. A multistage diffuser-type centrifugal pump as set forth in
claim 1 wherein the rubber member is a sleeve circumjacent the
impeller hub and secured thereto for rotation with the drive shaft,
and the stainless steel member is a bushing mounted on the
nonrotatable diffuser wall.
5. A multistage diffuser-type centrifugal pump as set forth in
claim 4 wherein the hubs of adjacent impellers are contiguous and
provide a stacked, nonfloating impeller construction, and including
bearing means for receiving the axial thrust from the
impellers.
6. A multistage diffuser-type centrifugal pump as set forth in
claim 1 wherein at least one of the members is tapered away from
the other member in the direction from the diffuser wall toward the
rear wall of the impeller.
7. A multistage diffuser-type centrifugal pump as set forth in
claim 6 wherein the tapered member has an annular surface adjacent
the taper and engaged with the periphery of the other member.
8. A multistage diffuser-type centrifugal pump as set forth in
claim 1 wherein the stainless steel member is mounted on the
impeller hub for rotation therewith, and the rubber member is a
bushing mounted on the diffuser wall, the bushing being shaped to
receive the end of the diffuser wall and having legs extending
along opposite sides of the diffuser wall to mount the bushing
thereon.
9. A multistage, diffuser-type centrifugal pump for pumping liquid
from a main pump inlet to a main pump outlet and including:
a rotatable drive shaft;
a plurality of pump impellers each having a central inlet opening,
a front wall extending outwardly from the central inlet opening, a
hub, a rear wall extending outwardly from the hub, impeller
passages extending between the front and rear walls from the
central inlet opening to the outer periphery of the impeller, means
slidably mounting the hub on the drive shaft for rotation therewith
but permitting limited axial movement of the impeller relative to
the shaft, and the impellers being disposed on the drive shaft with
their inlet openings facing in the same direction;
a pump casing surrounding the impellers and including a plurality
of walls each spaced axially forwardly of the front wall of a
respective impeller, a plurality of nonrotatable diffuser walls
each spaced axially rearwardly of the rear wall of a respective
impeller to define a plurality of impeller chambers, each diffuser
wall having a central opening spaced from the drive shaft, means
defining a plurality of diffuser passages for transferring liquid
from the periphery of each impeller chamber to the rear side of the
respective diffuser wall and to the inlet opening of the impeller
of a succeeding pump stage;
the difference between the liquid pressure acting on the rear wall
of each impeller and the liquid pressure at the inlet opening of
the impeller producing an axial hydraulic thrust on each impeller
in a direction toward the inlet opening, the impellers being
dimensioned in relation to the impeller chambers to permit
independent axial float within the respective chamber and along the
shaft whereby the impellers can shift as the hydraulic thrust
changes;
an annular rubber journal mounted on the drive shaft for rotation
therewith, the journal being located rearwardly of the rear wall of
the impeller and disposed in the central opening of the diffuser
wall, and the journal being spaced from at least one adjacent hub
to allow the axial float of the impeller; and
a stainless steel bushing mounted in the central opening of each
diffuser wall in fixed relation thereto, and the bushing being in
sealing engagement with the journal to provide a seal between the
impeller chamber and the diffuser passages to reduce backflow of
liquid and to provide a radial bearing for the drive shaft at each
pump stage.
10. In a multistage, diffuser-type centrifugal pump for pumping
liquid from a main pump inlet to a main pump outlet and including:
a rotatable drive shaft; a plurality of pump impellers each having
a hub engaged with the drive shaft for rotation therewith, a rear
wall extending outwardly from the hub, a central opening, a front
wall extending outwardly from the central opening, and impeller
passages extending between the front and rear walls toward the
outer periphery of the impeller; and a nonrotatable pump casing
surrounding the impellers and including a plurality of walls each
spaced axially forwardly of the front wall of a respective
impeller, a plurality of nonrotatable diffuser walls each spaced
axially rearwardly of the rear wall of a respective impeller to
define a plurality of impeller chambers, each diffuser wall having
a central opening spaced from the drive shaft, and means defining a
plurality of diffuser passages for transferring liquid from the
periphery of each impeller chamber to the rear side of the
respective diffuser wall and to the inlet opening of the impeller
of a succeeding pump stage; the improvement comprising: first means
mounted on the drive shaft for rotation therewith; the first means
being located rearwardly of the rear wall of the impeller and
disposed in the central opening of the diffuser wall; second means
at the central opening of the diffuser wall defining a surface in
sealing engagement with the member to provide a seal between the
impeller chamber and the diffuser passages to reduce backflow of
liquid; one of the first and second means being tapered away from
the other in the direction from the diffuser wall toward the rear
wall of the impeller to provide a diverging channel for the passage
of any foreign matter which becomes lodged at the seal and thereby
reduce the friction of the pump.
11. Apparatus according to claim 10 wherein the hub extends through
the central opening of the diffuser wall and the means being
tapered is a tapered surface on the hub.
12. Apparatus according to claim 10 wherein the means being tapered
is a tapered surface at the central opening of the diffuser wall,
and including a flat land adjacent the tapered surface, the land
being in contact with the other means over substantially its entire
area.
13. Apparatus according to claim 10 wherein the means being tapered
is made of rubber, and the other means is an annular stainless
steel member.
Description
BACKGROUND
The invention pertains generally to the field of pumps and more
particularly to a centrifugal pump having multiple stages and
diffusers.
Some wells tend to continually supply sand or other abrasives with
the water. The same condition exists, for a period of time, in
newly drilled wells that have not been properly cleaned. Increased
wear, caused by such abrasives, can greatly reduce the efficiency
of a centrifugal pump. In addition, increased clearances may allow
the shaft to whip during operation and this increases the rate of
wear. When there are heavy abrasives in the liquid, there is a
tendency for the pump to lockup and prevent the motor from
starting, or even stall the motor. This occurs when the abrasives
lodge in the seal between the hub and the diffuser.
SUMMARY
The present invention relates to new and improved construction for
centrifugal pumps having multiple stages and diffusers.
It is a general object of the present invention to provide a
centrifugal pump with improved performance and life when utilized
to pump liquids containing abrasives.
Another object is to provide a centrifugal pump which is
constructed and arranged to provide reduced wear.
Still another object is to provide a multistage centrifugal pump
with an improved radial bearing arrangement at each stage.
It is another object to provide a centrifugal pump with improved
seal construction between the impeller chamber and the diffuser
passages.
Yet another object of the present invention is to provide a
centrifugal pump constructed to reduce the tendency for the pump to
lockup when handling liquids containing abrasives.
It is another object of the present invention to provide a
centrifugal pump with a self-cleaning seal construction.
These and other objects and advantages of the present invention,
will become apparent as the same becomes better understood from the
following detailed description when taken in conjunction with the
accompanying drawings.
DRAWINGS
FIG. 1 is a vertical sectional view through a centrifugal pump unit
of one embodiment of the present invention;
FIG. 2 is an enlarged fragmentary sectional view of the embodiment
of FIG. 1;
FIG. 3 is a cross-sectional view taken generally along broken line
3--3 of FIG. 2 and on a smaller scale;
FIG. 4 is a sectional view through the rubber bushing utilized in
the embodiment of FIGS. 1-3; FIG. 5 is a fragmentary sectional view
similar to FIG. 2 but of a second embodiment of the invention;
FIG. 6 is a partial cross-sectional view taken along line 6--6 of
FIG. 5; and
FIGS. 7 and 8 are fragmentary sectional views similar to FIG. 2 but
of other embodiments of the invention.
DESCRIPTION
Reference is now made more particularly to the drawings which
illustrate the best presently known mode of carrying out the
invention and wherein similar reference characters indicate similar
parts throughout the several views.
Referring to FIG. 1, pump 20 has a drive shaft 22 driven by a motor
(not shown) mounted on the lower end of the pump and having a motor
shaft 23 connected to the shaft 22 through a coupling 25. The pump
has an outer sleeve 24 which contains a plurality of impeller
casings 26 and a plurality of impellers 28 arranged in the
respective casings. In this embodiment, the impellers 28 are
arranged to float relatively freely on the drive shaft 22 within
preselected limits.
The impellers 28 have hubs 38 slidably and nonrotatably mounted on
the drive shaft 22. The hubs 38 are internally splined to fit on
the splined drive shaft 22. A rear wall 40 extends radially from
hub 38 and a front wall 42 is spaced axially from the rear wall 40
as best shown in FIG. 2. The outer periphery of the rear wall is
advantageously spaced radially inwardly from the periphery of the
front wall to direct fluid upwardly to a succeeding pump stage.
Impeller vanes 44 separate the front and rear walls and define a
plurality of impeller passages for transferring fluid from the
inlet of the impeller to the outer periphery thereof when the
impellers are rotated. Vanes 44 are conveniently formed integral
with rear wall 40 on the front side thereof, and a plurality of
openings 48 are located in these vanes. Pins 46, extending from the
rear side of front wall 42, extend into openings 48 for assembly of
the completed impeller. The impellers may be economically
fabricated from a suitable plastic such as "Delrin." Front wall 42
is provided with a central impeller inlet 49 which leads to the
impeller passageways defined by the walls 40 and 42 and the vanes
44.
Each impeller 28 is contained in the casing 26. Each casing
includes an outer peripheral wall 52, a diffuser wall 56, and an
inlet or thrust wall 54. Walls 52, 54 and 56 define an impeller
chamber 58 for transferring fluid from the periphery of one
impeller to the inlet of the adjacent impeller of the next
succeeding pump stage. For this purpose, diffuser wall 56 is
provided with ramps 60 which extend upwardly from a lower edge 61
to an upper edge 62 (see FIG. 3). Diffuser vanes 64 spiral inwardly
on the rear side of diffuser wall 56 and terminate at an innner end
65. Thus fluid leaving the periphery of the impeller 28 travels
upwardly along ramps 60, through an opening 63 and inwardly along
diffuser passages 64a between diffuser vanes 64 to the impeller
inlet 49 of the next adjacent impeller of the succeeding pump
stage. The ramps 60 and impeller vanes 64 are herein shown as five
in number although any convenient number may be utilized.
Each of the aforedescribed impellers 28 and casings 26 for the
several stages of the pump are generally identical in construction
and like numerals are utilized to designate corresponding parts of
the several stage. The casings 26, each containing an impeller 28,
are advantageously stacked one on top of the other and held
together by outer sleeve 24 which surrounds the casings. Outer
sleeve 24 is secured to an upper discharge member 66 and a lower
motor mount 68. Motor mount 68 contains a main pump inlet 70 and
the impellers, all facing in the same direction, will transfer the
fluid from the main pump inlet 70 to a main pump outlet 72 in the
upper discharge member 66. Upper discharge member 66 also contains
a valve member 74 of any convenient construction.
During pumping, the liquid is transferred though the successive
impeller chambers as described above. The pressure of the fluid is
increased in step fashion in the successive pump stages and the
difference between the fluid pressures in each impeller chamber 58
and at the inlet of the respective impellers produces an axial
hydraulic thrust on the impellers in a direction toward the pump
inlet under certain operating conditions.
Each thrust wall 54 has a central opening adjacent the impeller
inlet. Seal means is provided at the impeller inlet 49 to limit
recirculation of fluid from the impeller chambers 58 back to the
respective inlet. In the embodiment shown, the seal means includes
an annular insert 78 disposed in the thrust wall central opening
and a washer 82 mounted at the front side of the impeller front
wall 42. Insert 78 is preferably formed of stainless steel and is
of L-shaped cross section. Washer 82 may be formed of various
different materials which provide good wear characteristics when in
rubbing contact with insert 78. The washer 82 cooperates with inlet
78 to provide a seal at the impeller inlet 49 as well as a bearing
when the impeller 28 is urged toward the inlet or front side.
As indicated previously, the hydraulic pressures are continually
increased through the successive pump stages. As one example, the
relative pressures of a middle pump stage may be about 12 p.s.i. at
the central inlet 49, about 20 p.s.i. at the outlet of the
impeller, and 24 p.s.i. in the diffuser passage 64a. At the same
time, the pressure at the center of the impeller chambers 58 may be
about 18 p.s.i. Thus there can be about a 6 pound differential
between the impeller passageway 64 leading to the inlet of the
succeeding pump stage and the central portion of the impeller
chamber 58. Backflow between these areas will reduce the efficiency
of the pump. Thus it is desirable to provide a seal between the
diffuser passages 64a and the impeller chamber 58. For this
purpose, an annular rubber member 90 is mounted on the drive shaft
22 and a stainless steel member 92 is mounted on the diffuser wall
56. As best seen in FIG. 4, rubber member 90 is generally L-shaped
in cross section having legs 94 and 96 and is internally splined as
at 98 to have a driving connection to the spline drive shaft 22. In
this embodiment, the rubber member 90 provides a journal and the
stainless steel member 92 is a bussing L-shaped in cross section,
engaged with the journal. Bushing 92 is preferably formed of
stainless steel and has a press fit in the nonrotatable diffuser
wall 56. As can be seen, journal 90 is mounted rearwardly of the
rear wall 40 of the impeller for rotation with the drive shaft and
impeller while the bushing 92 is nonrotatably mounted and in
engagement with the journal 90. These two members have a relatively
close fit to provide a seal between the impeller chamber 58 and the
diffuser passage 64a to reduce backflow of liquid therebetween.
Further, these members provide a radial bearing for the drive shaft
22 at each pump stage thereby eliminating the necessity for a
bearing in the pump head. Also, since the rubber journal 90 is a
separate part, it can be replaced without necessitating the
replacement of the whole impeller 28.
Since there is a differential in pressure between the impeller
chamber 58 and the diffuser passage 64a, there will be some flow
between members 90 and 92. When the fluid contains an abrasive,
such as sand, this flow can cause serious wear between the members.
Thus, the member 90 is preferably made of rubber so that it can be
deformed, pass any such abrasives, and return to its original seal
position without undue wear.
From the foregoing it is thought that the construction and
operation of the embodiment of FIGS. 1-4 will be readily
understood. Vanes 55 on the thrust plate 54 retard rotation of the
fluid at the front side of the impellers 28 to increase the
pressure thereat. The impellers are free to axially float in the
impeller chambers and move away from the vanes a distance such that
the axial hydraulic thrust of the impellers will be balanced. This
provides a self-regulating type of hydraulic balance for the
impellers. Since the impellers do not exert a large axial thrust on
the shaft 22, it is unnecessary to provide a large thrust bearing
for the pump drive shaft. The front and rear walls of the impellers
are moulded in separate pieces for ease of moulding and are held
together by the pressure conditions in the impeller chambers so as
to eliminate the necessity of a separate assembly step to rigidly
secure the sections together. The rubber journal 90 at the rear
side of the impeller 28 permits limited axial floating of the
impellers on the drive shaft, cooperates with the stainless steel
bushing 92 to provide a seal between the diffuser passages and the
impeller chamber, and yet is resilient to pass any abrasives that
may be contained in the fluid and which might otherwise tend to
lodge in the seal. Rubber member 90 and stainless steel bushing 92
provide a radial bearing at each pump stage thereby eliminating the
necessity of a bearing in the pump head.
In the embodiment of FIGS. 5 and 6, the majority of the parts are
identical to those described above and are identified by the same
numerals. There are some minor differences which will now be
described. The wall 54 has a larger central opening and a bushing
78', is mounted in that opening. The front wall 42 of the impeller
has a skirt 42a at its central opening 49 and in engagement with
the bushing 78'. The skirt and the bushing provide a radially seal
around the inlet opening 49.
The major differences in construction of this embodiment relate to
the impeller hub and the rubber journal. The impeller hub 38 has an
extension 38a at the rear side of the rear wall. The extremity of
extension 38a engages the front edge of a succeeding hub 38 thereby
providing a stacked (nonfloating) impeller. With this construction,
a bearing (not shown) is provided for receiving the axial thrust
from the impellers. The hub extension 38a has a plurality of
keyways 101 as best shown in FIG. 6. A rubber journal 90' is
mounted outwardly of the extension 38a at the rear side of the rear
wall 40 of the impeller. The rubber journal 90' is shaped to extend
into the keyways 101 and is thus keyed to the hub extension 38a for
rotation with the drive shaft 22. The rubber journal 90' cooperates
with the stainless steel bushing 92 in the manner described above
and for the same purposes.
In the embodiment of FIG. 7, all parts are identical with the
embodiment of FIG. 5 with the exception of the rubber journal. In
this embodiment, a rubber journal 90" is tapered inwardly away from
the stainless steel bushing 92 in the direction from the diffuser
wall 56 toward the rear wall 40 of the impeller. This provides a
channel which diverges from the higher pressure diffuser passageway
64a toward the lower pressure impeller chamber 58. This allows any
abrasives or grit that may be lodged in the seal between the rubber
journal 90" and the stainless steel bushing 92 to be more easily
passed into the lower pressure impeller chamber 58. It has been
found that this type of construction greatly reduces the tendency
for the pump to lockup and stall the motor, or prevent the motor
from starting when there is sand or other abrasives in the water
being pumped. The seal between the rubber journal 90" and the
stainless steel bushing 92 still prevents excessive bypassing of
fluid between the diffuser passageway and impeller chamber.
In the embodiment of FIG. 8, the tapered clearance arrangement is
provided on the bushing instead of the journal. In this embodiment,
a journal 102 is formed of stainless steel and is keyed to the hub
extension 38a. The journal 102 could be directly mounted on the
shaft 22, if desired. A bushing 103 is advantageously formed of
rubber and has legs 104 and 105 extending on opposite sides of the
diffuser wall 56. Leg 104 is advantageously shorter than leg 105
for ease in assembly. As shown, bushing 103 is tapered away from
journal 102 and in the same direction as described above. If
desired, the tapered clearance arrangement could be provided
integrally with a plastic hub or could be provided by a tapered
central opening in the diffuser wall 56.
From the foregoing it is believed that the construction and
function of the various embodiments will be readily understood.
Each embodiment provides a centrifugal pump with improved life when
utilized for pumping liquids containing abrasives. Each embodiment
provides an improved radial bearing arrangement at each stage of
the pump and an improved self-cleaning seal construction between
the impeller chamber and the diffuser passages. The embodiments of
FIGS. 7 and 8 provide a construction which reduces the tendency for
the pump to lockup when handling liquids containing abrasives.
While preferred embodiments of the invention has herein been
illustrated and described, this has been done by way of
illustration and not limitation, and the invention should not be
limited except as required by the scope of the appended claims.
* * * * *