U.S. patent application number 14/083272 was filed with the patent office on 2014-03-13 for integrated endshield and pump volute for an electric pump and method of forming an electric pump.
This patent application is currently assigned to NIDEC MOTOR CORPORATION. The applicant listed for this patent is Nidec Motor Corporation. Invention is credited to George A. Clark, Richard J. Fadler, Phillip S. Johnson, Brian P. Klein, Robert J. Schmidt.
Application Number | 20140072464 14/083272 |
Document ID | / |
Family ID | 43380974 |
Filed Date | 2014-03-13 |
United States Patent
Application |
20140072464 |
Kind Code |
A1 |
Fadler; Richard J. ; et
al. |
March 13, 2014 |
INTEGRATED ENDSHIELD AND PUMP VOLUTE FOR AN ELECTRIC PUMP AND
METHOD OF FORMING AN ELECTRIC PUMP
Abstract
An electric pump comprises a stator, a rotor, and an endshield.
The interface plate is fixed to the stator and is configured to
couple the electric motor to a pump. The pump volute is formed as
an integral portion of the endshield, thereby minimizing the axial
length of the electric pump. A drainage passageway is provided on
the endshield to harmlessly drain away any fluid that seeps past
the pump's seals. In one embodiment of the invention, the drainage
passageway is a groove that faces the stator and is configured to
facilitate the evaporation of and leak fluid by channeling the
fluid near the stator, which warms the fluid and thereby increases
the fluid's evaporation rate.
Inventors: |
Fadler; Richard J.; (St.
Charles, MO) ; Schmidt; Robert J.; (St. Peters,
MO) ; Johnson; Phillip S.; (Granite City, IL)
; Klein; Brian P.; (St. Louis, MO) ; Clark; George
A.; (Lewis Center, OH) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Nidec Motor Corporation |
St. Louis |
MO |
US |
|
|
Assignee: |
NIDEC MOTOR CORPORATION
St. Louis
MO
|
Family ID: |
43380974 |
Appl. No.: |
14/083272 |
Filed: |
November 18, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
12492022 |
Jun 25, 2009 |
8585378 |
|
|
14083272 |
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Current U.S.
Class: |
417/423.11 ;
417/423.12 |
Current CPC
Class: |
F04D 29/445 20130101;
F04D 29/628 20130101; H02K 5/124 20130101; F04D 13/06 20130101;
H02K 5/15 20130101; H02K 5/1732 20130101; F05D 2260/6022 20130101;
Y10T 29/49009 20150115; H02K 2205/09 20130101 |
Class at
Publication: |
417/423.11 ;
417/423.12 |
International
Class: |
F04D 13/06 20060101
F04D013/06; F04D 29/44 20060101 F04D029/44 |
Claims
1. An electric pump for use in an appliance, said electric pump
comprising: a stator; a rotor including a shaft rotatable about an
axis; a pump volute; an impeller at least in part positioned inside
the pump volute; an endshield fixed to the stator and defining a
shaft opening, said shaft extending through the shaft opening along
the axis; and a seal positioned between the endshield and the
shaft, said shaft including an impeller section at least
substantially adjacent the impeller, and a motor section at least
substantially adjacent the stator, said seal positioned between the
impeller section and the motor section, said seal and said
endshield configured to cooperatively at least substantially
prevent ingress of fluid from the impeller section to the motor
section, said endshield and said volute being monolithically
formed, said endshield at least in part defining a drainage
passageway in fluid communication with the motor section such that
any fluid that leaks to the motor section from the impeller section
is received by the drainage passageway.
2. The electric pump of claim 1, said pump further comprising a
bearing that supports the shaft, said endshield supporting the
bearing.
3. The electric pump of claim 2, said bearing directly engaging the
motor section of the shaft.
4. The electric pump of claim 1, said endshield presenting a front
face facing the volute and a back face facing the stator, said back
face at least in part defining the drainage passageway.
5. The electric pump of claim 1, said drainage passageway
comprising a groove exposed to the stator and defined by the
endshield.
6. The electric pump of claim 1, said drainage passageway extending
to a reservoir.
7. The electric pump of claim 6, said endshield defining the
reservoir, said reservoir being exposed to the stator.
8. The electric pump of claim 7, said reservoir being spaced from
the stator and configured such that heat from the stator is
operable to initiate evaporation of fluid retained in the
reservoir.
9. The electric pump of claim 1, said volute comprising a spiral
formation.
10. The electric pump of claim 1, said endshield supporting the
stator in the appliance.
11. An electric pump for use in an appliance, said electric pump
comprising: a rotor including a shaft rotatable about an axis; a
stator presenting opposite ends spaced along the axis; a pump
volute; and an endshield fixed to one of the ends of the stator,
said endshield and said volute being monolithically formed.
12. The electric pump of claim 11, further comprising: an impeller
at least in part positioned inside the pump volute; and a seal
positioned between the endshield and the shaft, said endshield
defining a shaft opening, said shaft extending through the shaft
opening along the axis, said shaft including an impeller section at
least substantially adjacent the impeller, and a motor section at
least substantially adjacent the stator, said seal positioned
between the impeller section and the motor section, said seal and
said endshield configured to cooperatively at least substantially
prevent ingress of fluid from the impeller section to the motor
section, said endshield at least in part defining a drainage
passageway in fluid communication with the motor section such that
any fluid that leaks thereto from the impeller section is received
by the drainage passageway.
13. The electric pump of claim 12, said drainage passageway
comprising a groove defined by the endshield.
14. The electric pump of claim 13, said groove being exposed to the
stator.
15. The electric pump of claim 12, said drainage passageway
extending to a reservoir.
16. The electric pump of claim 12, said endshield defining the
reservoir, said reservoir being exposed to the stator.
17. The electric pump of claim 16, said reservoir being spaced from
the stator and configured such that heat from the stator is
operable to initiate evaporation of fluid retained in the
reservoir.
18. The electric pump of claim 11, said pump further comprising a
bearing that supports the shaft, said endshield supporting the
bearing.
19. An improved electric pump comprising a stator, a rotor, an
endshield, and a bearing, the rotor having a rotor shaft, the
endshield being fixed to the stator and comprising a shaft opening,
the shaft opening extending through the endshield, the rotor shaft
extending through the shaft opening, the bearing being supported by
the endshield, the bearing at least partially supporting the rotor
shaft in a manner allowing the rotor shaft to revolve relative to
the endshield, the improvement comprising: a fluid pump volute, the
fluid pump volute and the endshield being monolithically formed
together as a single part; a drainage passageway formed in the
endshield, the drainage passageway extending downward from the
shaft opening and being configured and adapted to channel liquid
downward from the shaft opening via gravity; and a fluid reservoir
formed by the endshield, the drainage passageway operatively
connecting the shaft opening to the fluid reservoir, the fluid
reservoir being exposed to and spaced from a surface of the
stator.
20. The electric pump of claim 19, wherein the fluid reservoir
comprises a recess in a generally horizontal surface of the
endshield that is beneath the stator.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of U.S. patent
application Ser. No. 12/492,022, filed Jun. 25, 2009, which is
incorporated herein by reference in its entirety.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
[0002] Not Applicable.
APPENDIX
[0003] Not Applicable.
BACKGROUND OF THE INVENTION
[0004] 1. Field of the Invention
[0005] This invention pertains generally to electric pumps. More
specifically, this invention pertains to an electric pump that
comprises a novel endshield.
[0006] 2. General Background
[0007] Electric fluid pumps, such as those used in appliances,
often comprise a centrifugal fluid pump attached to one end of an
electric motor. Typically, the centrifugal pump comprises an
impeller that rotates in a volute. The impeller is rotationally
driven by the rotor of an electric motor and the volute is
typically fastened to the adjacent endshield of the electric motor.
One or more seals typically inhibit water or other fluids from
traveling along or around the rotor shaft to the core of the
electric motor's stator. However, over time and as the pump wears,
it is not uncommon for at least some fluid to migrate past the seal
or seals. Fluid seepage that migrates into an adjacent electric
motor can negatively impact the efficient operation of the motor or
shorten its useful life. For these reasons, the electric motor and
pump are typically oriented relative to each other in a manner such
that the electric motor is not directly beneath the pump. Thus it
is often desirable to position the electric motor and the pump
side-by-side. While positioning the electric motor to the side,
rather than beneath the pump, inhibits seepage into the motor,
liquid seepage from the pump bearings still may nonetheless travel
along or around the rotor shaft toward the stator.
[0008] In view of these concerns, it is known to provide an
electric pump with a liquid drainage cavity that is specifically
configured to prevent liquid that has seeped past the rotor shaft
bearing of the pump from being drawn by capillary action into the
stator of the electric motor. The cavity is typically formed in the
interface plate of the electric motor and encircles the rotor shaft
in a manner providing an annular void around a portion of the
shaft. The cavity thereby provides a place for seeped liquid to
migrate and prevents capillary action from drawing the liquid into
the stator, which would likely occur if there was little space
around the shaft. Assuming the liquid seepage is slight, the cavity
can serve as a reservoir for such liquid and thereby prevent the
liquid from migrating into the stator. However, if the seepage is
too great, the fluid will fill the cavity and then migrate into the
stator. For this reason, some electric pumps comprise a drainage
passageway configured to drain the cavity.
[0009] In addition to the concerns discussed above, there is also
an endless desire to minimize the size of electric pumps without
compromising their performance. The incorporation of a cavity for
draining fluid seepage typically increases the overall length of an
electric pump and therefore can be undesirable.
SUMMARY OF THE INVENTION
[0010] The present invention provides for a shorter electric fluid
pump and facilitates the evaporation of fluid leakage that manages
to seep past the seals of the pump volute.
[0011] In one aspect of the invention, an improved electric pump
comprises a stator, a rotor, an endshield, and a bearing. The rotor
has a rotor shaft. The endshield is fixed to the stator and
comprises a shaft opening. The shaft opening extends through the
endshield. The rotor shaft extends through the shaft opening. The
bearing is supported by the endshield and at least partially
supports the rotor shaft in a manner allowing the rotor shaft to
revolve relative to the endshield. The improvement comprises a
fluid pump volute formed as an integral portion of endshield.
Incorporating the fluid pump volute in the endshield reduces the
length of the electric fluid pump since a separate fluid pump
volute is no longer required.
[0012] In another aspect of the invention, an electric pump
comprises a stator, a rotor, an endshield, and a bearing. The rotor
has a rotor shaft. The endshield is fixed to the stator and
comprises a shaft opening and a fluid pump volute. The shaft
opening extends through the endshield. The rotor shaft extends
through the shaft opening. The bearing is supported by the
endshield and at least partially supports the rotor shaft in a
manner allowing the rotor shaft to revolve relative to the
endshield.
[0013] In yet another aspect of the invention, an electric pump
comprises a stator, a rotor, an endshield, and a bearing. The rotor
has a rotor shaft. The endshield is fixed to the stator and
comprises a shaft opening and a drainage groove. The shaft opening
extends through the endshield. The rotor shaft extends through the
shaft opening. The drainage groove extends downward from the shaft
opening and is configured and adapted to channel liquid downward
from the shaft opening via gravity. The drainage groove faces the
stator. The bearing is supported by the endshield and at least
partially supports the rotor shaft in a manner allowing the rotor
shaft to revolve relative to the endshield. This facilitates the
evaporation of any fluid seepage.
[0014] In still another aspect of the invention, a method of
forming an electric motor comprises molding an endshield as a
single monolithic part in a manner such that the endshield
comprises a fluid pump volute and a shaft opening. The shaft
opening extends through the endshield. The method further
comprises, attaching the endshield to a stator in a manner such
that the fluid pump volute faces away from the stator. Still
further, the method comprises positioning a bearing in the shaft
opening of the endshield and positioning a rotor shaft in manner
such that the rotor shaft extends through the bearing and through
the shaft opening of the endshield. Using this method, the length
of electric fluid pumps can be minimized.
[0015] For purposes of describing the invention, the electric pumps
are described herein as being in particular orientations.
Nonetheless, it should be appreciated that when the electric pump
is utilized, the orientation of the electric pump may be other than
described herein. Thus, the orientations described herein a merely
for the purpose of describing relative orientation of various
features of the invention, unless such orientations are
specifically claimed.
[0016] Further features and advantages of the present invention, as
well as the operation of the invention, are described in detail
below with reference to the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] FIG. 1 is a perspective view of one embodiment of an
electric motor in accordance with the invention, showing the front,
top, and right side of the electric motor.
[0018] FIG. 2 is a perspective view of the electric motor as shown
in FIG. 1 but is shown with the volute housing removed to reveal
the impeller within the volute of the endshield.
[0019] FIG. 3 is a perspective view of the endshield of the
electric motor, showing the front, top, and right side of
thereof.
[0020] FIG. 4 is a perspective view of the endshield of the
electric motor, showing the rear, top, and right side of
thereof.
[0021] FIG. 5 is a perspective view of the endshield of the
electric motor, showing the rear, bottom, and right side of
thereof.
[0022] FIG. 6 is a detail perspective view of the endshield as
shown in FIG. 5.
[0023] FIG. 7 is a cross-section view of the electric pump showing
the left half of the pump as would be viewed from the right.
[0024] FIG. 8 is a perspective view of the endshield of the
electric motor, showing the rear, top, and left side thereof.
[0025] Reference numerals in the written specification and in the
drawing figures indicate corresponding items.
DETAILED DESCRIPTION
[0026] An embodiment of an electric pump in accordance with the
invention is shown in FIGS. 1 and 7. The electric pump 20 comprises
a stator 22, a rotor 24 (shown in FIG. 7), and an endshield 26. The
stator 22 surrounds most of the rotor 24 and is configured to be
fixed in place within an appliance. The rotor 24 is rotationally
mounted to the stator 22 and comprises a rotor shaft 28 that
extends beyond the stator.
[0027] The endshield 26 is rigidly fixed to end of the stator 22.
The endshield 26 is preferably moulded out of plastic and therefore
is highly resistant to corrosion. The front side of the endshield
26 (the side that faces away from the stator 22) comprises a fluid
pump volute 30 which houses an impeller 32 that is operatively
connected to one end of the rotor shaft 28 for rotation therewith.
A volute housing 34 is attached to the endshield 26 and encircles
the volute 30. The volute housing 34 comprises a fluid inlet 36 and
a fluid outlet 38. In operation, the impeller 32 rotates with the
rotor 24 and draws fluid into the volute 30 via the fluid inlet 36
of the volute housing 34. The fluid drawn in is then forced against
the wall of the volute 30 by the impeller 32. The volute 30 then
channels the fluid to the fluid outlet 38 of the volute housing
34.
[0028] The rotor shaft 28 extends through a shaft opening 40 formed
through the endshield 26. The shaft opening 40 comprises a pocket
42 that is configured to receive a bearing 44 (shown in FIG. 7).
The pocket 42 has undulations that are configured to properly
position the bearing 44, regardless of the wear of the molds used
to form the endshield 26. These undulations also prevent fluid from
backing up against the front of the bearing 44 by providing a path
for fluid to pass through the shaft opening 40 around the bearing.
As is most clearly shown in FIG. 6, a drainage groove 46 is molded
into the rear face of the endshield 26 and extends downward from
the end of the shaft opening 40. As the drainage groove 46 extends
downward, it also extends toward the front of the electric pump 20.
This allows the pocket 42 of the endshield and the bearing 44 to be
positioned within the stator 22 in a manner that minimizes the
axial length of the electric pump 20. The drainage groove 46 is
relatively narrow such that the cohesion tension of the fluid being
channeled prevents the fluid from dripping straight downward. The
drainage groove 46 terminates at the vertical wall portion 48 of
the endshield 26. From there, fluid is able to travel down against
the vertical wall 48 until is reaches a generally horizontal
surface 48 that is positioned beneath the front end of the stator
22. The horizontal surface 48 serves as a reservoir for any fluid
discharged from the drainage groove 46 by provided a place for such
fluid to pool.
[0029] In use, any fluid that manages to leak past the seals 52 of
the electric pump 20 and migrate toward the stator 22 is able to
pass through the shaft opening 40 of the endshield 26 and may
ultimately reach the drainage groove 46 before evaporating. If it
does, the drainage groove 46 will channel the fluid down to the
generally horizontal surface 50 of the endshield 26 that lies
beneath the front end of the stator 22. Any fluid that collects on
the horizontal surface 50 is exposed to the heat of the stator 22,
which facilitates the evaporation of the fluid. If the amount of
fluid leakage is too excessive for the horizontal surface 50 to
hold, the excess is able to flow over the rear edge of the surface
and drain out of the electric pump 20. At no point does the fluid
make contact with the stator 22 itself.
[0030] In one or more alternative embodiments, the configuration of
the horizontal surface 50 may be altered, modified, or additions
made thereto so that fluid leakage tends collect thereon rather
than flow over the rear edge of the surface and drain out of the
electric pump 20. For example, as depicted in FIG. 8, a recess 55
may be formed in the horizontal surface 50. Although recess 55 is
depicted as being rectangular, such a recess may be of essentially
any appropriately sized configuration or shape. Alternatively, the
generally horizontal surface 50 may be formed to have an incline to
collect fluid leakage by, for example, skewing the parting plane of
a mold from being perpendicular to the rotor axis. Still further, a
barrier to the movement of fluid leakage may be placed onto the
generally horizontal surface 50 at or near the rear edge (e.g., a
strip of foam or a bead of caulk).
[0031] By incorporating the fluid pump volute 30 as an integral
portion of the endshield 26, the overall length of the electric
pump 20 is significantly reduced compared to equally powerful prior
art pumps. This allows the electric pump 20 to be incorporated into
compact appliances.
[0032] In view of the foregoing, it should be appreciated that the
invention achieves the several advantages over prior art electric
pumps.
[0033] As various modifications could be made in the constructions
and methods herein described and illustrated without departing from
the scope of the invention, it is intended that all matter
contained in the foregoing description or shown in the accompanying
drawings shall be interpreted as illustrative rather than limiting.
For example, while the drainage passageway of the embodiment
described above as being an exposed channel or groove, the drainage
passageway could alternatively be cylindrical drill hole
passageway. Thus, the breadth and scope of the present invention
should not be limited by any of the above-described exemplary
embodiments, but should be defined only in accordance with the
following claims appended hereto and their equivalents.
[0034] It should also be understood that when introducing elements
of the present invention in the claims or in the above description
of exemplary embodiments of the invention, the terms "comprising,"
"including," and "having" are intended to be open.sub.iended and
mean that there may be additional elements other than the listed
elements. Additionally, the term "portion" should be construed as
meaning some or all of the item or element that it qualifies.
Moreover, use of identifiers such as first, second, and third
should not be construed in a manner imposing any relative position
or time sequence between limitations. Still further, the order in
which the steps of any method claim that follows are presented
should not be construed in a manner limiting the order in which
such steps must be performed.
* * * * *