U.S. patent application number 15/556179 was filed with the patent office on 2018-02-15 for impeller for centrifugal pumps.
This patent application is currently assigned to Ebara Corporation. The applicant listed for this patent is Ebara Corporation. Invention is credited to Fabio BALBO, Renato GROPPO, So KUROIWA, Mariano MATTEAZZI, Masashi OBUCHI, Dai SAKIHAMA.
Application Number | 20180045213 15/556179 |
Document ID | / |
Family ID | 53177841 |
Filed Date | 2018-02-15 |
United States Patent
Application |
20180045213 |
Kind Code |
A1 |
GROPPO; Renato ; et
al. |
February 15, 2018 |
IMPELLER FOR CENTRIFUGAL PUMPS
Abstract
An impeller for centrifugal pumps has a first disk element,
functionally arranged toward the inlet, which is coaxial to and
faces a second disk element, which is functionally arranged toward
the delivery and is connected rigidly to the first disk element by
virtue of a series of angularly spaced vanes and is provided
centrally with a means for fixing to a transmission shaft. The
particularity of the present invention resides in that the impeller
includes a series of openings formed in the substantially
peripheral region of the second disk element, between pairs of
adjacent vanes, substantially at the areas subjected to the
greatest axial thrust.
Inventors: |
GROPPO; Renato; (Cles
(Trento), IT) ; BALBO; Fabio; (Cles (Trento), IT)
; MATTEAZZI; Mariano; (Cles (Trento), IT) ;
OBUCHI; Masashi; (Tokyo, JP) ; SAKIHAMA; Dai;
(Tokyo, JP) ; KUROIWA; So; (Tokyo, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Ebara Corporation |
Tokyo |
|
JP |
|
|
Assignee: |
Ebara Corporation
Tokyo
JP
|
Family ID: |
53177841 |
Appl. No.: |
15/556179 |
Filed: |
March 18, 2016 |
PCT Filed: |
March 18, 2016 |
PCT NO: |
PCT/JP2016/059789 |
371 Date: |
September 6, 2017 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F04D 29/30 20130101;
F04D 17/08 20130101; F04D 29/2266 20130101; F04D 1/06 20130101 |
International
Class: |
F04D 29/22 20060101
F04D029/22; F04D 29/30 20060101 F04D029/30 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 20, 2015 |
IT |
102015902339796 |
Claims
1. An impeller for centrifugal pumps comprising a first disk
element, functionally arranged toward the inlet, which is coaxial
to and faces a second disk element, which is functionally arranged
toward the delivery; said second disk element being connected
rigidly to said first disk element by angularly spaced vanes and
being centrally provided with a fastening means for fastening to a
transmission shaft; said impeller being characterized in that it
comprises openings formed in the substantially peripheral region of
said second disk element, between pairs of adjacent vanes,
substantially at the areas subjected to the greatest axial
thrust.
2. The impeller according to claim 1, characterized in that the
radially peripheral side of each of said openings extends at a
distance that is shorter than that of the peripheral edge of said
second disk element, with respect to the rotation axis of said
impeller.
3. The impeller according to claim 1, characterized in that said
openings are constituted by contoured slots that are formed in the
substantially peripheral region of said second disk element,
between pairs of adjacent vanes; the radially peripheral side of
each of said contoured slots having an arc-like profile with a
convexity facing said rotation axis.
4. The impeller according to claim 3, characterized in that each of
said contoured slots has a contoured profile that is opposite with
respect to said arc-like profile.
5. The impeller according to claim 4, characterized in that said
contoured profile has a curved portion with a convexity facing said
rotation axis.
6. The impeller according to claim 4, characterized in that said
contoured profile has a curved portion with a convexity facing the
outside of said second disk element.
7. The impeller according to claim 4, characterized in that said
arc-like profile and said contoured profile are joined by at least
one substantially radially extended tab.
8. The impeller according to claim 1, characterized in that said
openings are constituted by through holes formed in the
substantially peripheral region of said second disk element,
between pairs of adjacent vanes.
9. The impeller according to claim 1, characterized in that the
centers of said through holes are formed substantially along a
circular arc that is centered with respect to said rotation
axis.
10. The impeller according to claim 1, characterized in that the
centers of said through holes are formed substantially along two or
more circular arcs that are concentric and centered with respect to
said rotation axis.
11. The impeller according to claim 1, characterized in that the
centers of said through holes are formed substantially along
circular arcs, the center of which is located outside said second
disk element.
12. The impeller according to claim 1, characterized in that said
fastening means comprises a hub mechanically associated with said
transmission shaft; said hub being opposite with respect to a
collar having a larger diameter than the diameter of said rotation
axis; said collar being provided on said first disk element.
13. The impeller according to claim 1, characterized in that said
second disk element has a diameter that is substantially equal to,
or smaller than, the diameter of said first disk element.
14. A centrifugal pump comprising a substantially hollow body that
accommodates at least one impeller that is fastened to a
transmission shaft which can rotate about a rotation axis; said
transmission shaft being rotated by a motor means; said impeller
comprising a first disk element, functionally arranged toward the
inlet, which is coaxial to and faces a second disk element, which
is functionally arranged toward the delivery; said second disk
element being connected rigidly to said first disk element by
angularly spaced vanes and being centrally provided with a
fastening means for fastening to a transmission shaft; said
impeller being characterized in that it comprises openings formed
in the substantially peripheral region of said second disk element,
between pairs of adjacent vanes, substantially at the areas
subjected to the greatest axial thrust.
Description
TECHNICAL FIELD
[0001] The present invention relates to an impeller for centrifugal
pumps, particularly of the type with one or more stages.
BACKGROUND ART
[0002] As is known, a centrifugal pumps has an impeller
conventionally made of a pair of shaped disk bodies facing each
other so as to form a gap within which a series of vanes that
connect the two disks are arranged.
[0003] Centrally to each impeller there is a hub, or an equivalent
coupling device, that allows to fasten the impeller to a
transmission shaft that is turned by a motor means.
SUMMARY OF THE INVENTION
Technical Problem
[0004] Although impellers of the known type are widely used, they
have drawbacks; among these, perhaps the most important is linked
to the generation of axial thrusts.
[0005] The impeller of a centrifugal pump is in fact subjected to
different pressures that act on the two faces: a pressure lower
than the atmospheric pressure generally acts on the inlet side,
while a pressure substantially equal to the delivery pressure acts
on the opposite face. This produces an axial thrust which can even
be considerable, such as to create great losses in terms of
efficiency and overloads that damage the bearings of the motor.
[0006] Those problems are emphasized in the case of multistage
pumps.
[0007] In an attempt to solve the problems linked to the generation
of axial thrusts, some manufacturers of multistage pumps key half
of the impellers in the opposite direction with respect to the
remaining ones.
[0008] However, such solution creates significant difficulties in
making the internal passage channels.
[0009] The prior art also includes a impeller for centrifugal pumps
disclosed in the Italian patent application no. VI2014A000271, to
this same applicant. Such impeller effectively solves the problems
described above, but requires the provision of disk elements having
different diameters.
Solution to the Problem
[0010] The aim of the invention is to solve the problems described
above, providing a impeller for centrifugal pumps that allows to
reduce axial thrusts, at the same time ensuring maximum efficiency,
and provides for the use of disk elements with the same
diameter.
[0011] Within the scope of this aim, a particular object of the
invention is to provide an impeller that allows to solve the
problems linked to the traction that is usually generated on the
transmission shaft.
[0012] Another object of the invention is to provide an impeller
that allows to preserve the bearings of the motor.
[0013] Another object of the invention is to provide an impeller
that can be manufactured with a small number of components and is
therefore advantageous also from a purely economic standpoint.
[0014] This aim, these objects and others that will become better
apparent hereinafter are achieved by an impeller for centrifugal
pumps comprising a first disk element, functionally arranged toward
the inlet, which is coaxial to and faces a second disk element,
which is functionally arranged toward the delivery; said second
disk element being connected rigidly to said first disk element by
angularly spaced vanes and being centrally provided with a
fastening means for fastening to a transmission shaft; said
impeller being characterized in that it comprises openings formed
in the substantially peripheral region of said second disk element,
between pairs of adjacent vanes, substantially at the areas
subjected to the greatest axial thrust.
[0015] The present invention also relates to a centrifugal pump
comprising a substantially hollow body that accommodates at least
one impeller that is fastened to a transmission shaft which can
rotate about a rotation axis; said transmission shaft being rotated
by a motor means; said impeller comprising a first disk element,
functionally arranged toward the inlet, which is coaxial to and
faces a second disk element, which is functionally arranged toward
the delivery; said second disk element being connected rigidly to
said first disk element by angularly spaced vanes and being
centrally provided with a fastening means for fastening to a
transmission shaft; said impeller being characterized in that it
comprises openings formed in the substantially peripheral region of
said second disk element, between pairs of adjacent vanes,
substantially at the areas subjected to the greatest axial
thrust.
Advantageous Effects of the Invention
[0016] The impeller according to the invention allows to
considerably reduce the axial thrusts but at the same time ensure
maximum efficiency and head.
[0017] In fact, by emptying the areas that are subjected to the
highest pressure in the second disk element, i.e. by forming the
openings, it is possible to reduce the forces that generate the
axial thrust.
[0018] Also, head and efficiency are not reduced because the
profile of these openings is fully included within the second disk
element.
[0019] The impeller according to the present invention allows to
solve the problems linked to the traction that is usually generated
on the transmission shaft of centrifugal pumps with one or more
stages. This allows, for example, to avoid damage to the bearings
of the motor.
BRIEF DESCRIPTION OF THE DRAWINGS
[0020] Further characteristics and advantages will become better
apparent from the description of preferred but not exclusive
embodiments of a impeller according to the invention, illustrated
by way of nonlimiting example in the accompanying drawings,
wherein:
[0021] FIG. 1 is a front view of an impeller according to the
invention;
[0022] FIG. 2 is a rear view of an impeller according to the
invention;
[0023] FIG. 3 is a sectional side view of the impeller according to
the invention;
[0024] FIG. 4 is a front view of an impeller according to a further
embodiment of the invention;
[0025] FIG. 5 is a rear view of the impeller of FIG. 4;
[0026] FIG. 6 is a sectional side view of the impeller of FIGS. 4
and 5;
[0027] FIG. 7 is a front view of an impeller according to a further
embodiment of the invention;
[0028] FIG. 8 is a rear view of the impeller of FIG. 7;
[0029] FIG. 9 is a sectional side view of the impeller of FIGS. 7
and 8;
[0030] FIG. 10 is a front view of an impeller according to a
further embodiment of the invention;
[0031] FIG. 11 is a rear view of the impeller of FIG. 10;
[0032] FIG. 12 is a sectional side view of the impeller of FIGS. 10
and 11;
[0033] FIG. 13 is a front view of an impeller according to a
further embodiment of the invention;
[0034] FIG. 14 is a rear view of the impeller of FIG. 13;
[0035] FIG. 15 is a sectional side view of the impeller of FIGS. 13
and 14;
[0036] FIG. 16 is a front view of an impeller according to a
further embodiment of the invention;
[0037] FIG. 17 is a rear view of the impeller of FIG. 16;
[0038] FIG. 18 is a sectional side view of the impeller of FIGS. 16
and 17.
DESCRIPTION OF THE EMBODIMENTS
[0039] FIGS. 1 to 3 illustrate an impeller for a centrifugal pumps,
globally designated by the reference numeral 1, according to the
invention.
[0040] The example illustrated herein relates to the case in which
the impeller 1 is used in a multistage centrifugal pump; however,
it is evident to the person skilled in the art that the impeller
according to the present invention can also be fitted on pumps of
another type.
[0041] The multistage centrifugal pump, which is per se known and
is not shown in the figures, is constituted by a substantially
hollow body that accommodates a set of impellers provided according
to the present invention, which are coaxially fastened to a
transmission shaft that is turned by a motor means.
[0042] The impeller 1 includes a first disk element 2, which is
functionally arranged towards the inlet, and a second disk element
3, which is functionally arranged towards the delivery.
[0043] The diameter of the second disk element 3 is substantially
equal to, or slightly smaller than, the diameter of the first disk
element 2.
[0044] The two disk elements 2 and 3 are coaxial to a rotation axis
1000 and face each other so as to form a substantially cylindrical
interspace.
[0045] Vanes 4 are arranged within the interspace and rigidly
connect the first disk element 2 to the second disk element 3.
[0046] The vanes 4, which are angularly distributed around the
rotation axis 1000, extend from the center toward the peripheral
region of the two disk elements 2 and 3, without protruding
outward, following an adapted profile.
[0047] In the illustrated solution, for example, the vanes 4 are
curved so as to form ducts that diverge and are arranged
radially.
[0048] Advantageously, the second disk element 3 is fastened to a
transmission shaft by means of a fastening means. The transmission
shaft, which is not shown in the figures, rotates about the
rotation axis 1000.
[0049] The fastening means comprises a hub 5, which can be
associated mechanically with the transmission shaft, provided at
the center of the second disk element 3.
[0050] A through hole 6 is centrally provided on the first disk
element 2, opposite to the hub 5; the through hole 6 has a diameter
that is larger than that of the transmission shaft.
[0051] The through hole 6 is connected to a collar 7 that protrudes
from the first disk element 2.
[0052] In practice, when the impeller 1 is mounted on the
transmission shaft, the collar 7 surrounds the shaft, forming an
annular opening that constitutes the intake of the impeller.
[0053] According to the present invention, the impeller 1 includes
a series of openings formed in the substantially peripheral region
of the second disk element 3, between pairs of adjacent vanes 4, in
which it is possible to identify the areas of the disk that are
subject to the greatest axial thrust.
[0054] The radially peripheral side of each opening extends for a
distance that is shorter than that of the peripheral edge of the
second disk element 3, with respect to the rotation axis 1000.
[0055] In other words, the openings are completely included within
the profile of the second disk element 3.
[0056] In the embodiment shown in FIGS. 1 to 3, the openings are
constituted by shaped slots 8 provided in the peripheral region of
the second disk element 3, between pairs of adjacent vanes 4.
[0057] Each contoured slot 8 has an arc-like profile 9, at the
radially peripheral side; the arc-like profile 9 has a convexity
facing the rotation axis 1000.
[0058] The arc-like profile 9 is connected with an opposite
contoured profile 10, which, in the example shown in FIGS. 1 to 3,
has a curved portion, with the convexity facing the rotation axis
1000.
[0059] FIGS. 4 to 6 show an impeller, generally designated by the
reference numeral 101, which is similar to the impeller 1 but is
provided with contoured profiles 110 with the convexity facing the
outside of the second disk element 3.
[0060] According to the embodiment shown in FIGS. 7 to 9, in which
the impeller according to the invention is generally designated by
the reference numeral 201, the arc-like profiles 9 and the
contoured profiles 10, or likewise the contoured profiles 110, of
the contoured slots 8 are joined by one or more radially extended
tabs 211 that have the function of stiffening the structure.
[0061] According to the embodiment illustrated in FIGS. 10 to 12,
in which the impeller according to the invention is designated by
the reference numeral 301, the openings are constituted by through
holes 308 provided in the substantially peripheral region of the
second disk element 3, between pairs of adjacent vanes 4.
[0062] In the example shown in FIGS. 10 to 12, the centers of the
through holes 308 are arranged substantially along an arc of a
circumference that is centered on the rotation axis 1000; however,
it is evident to the person skilled in the art that the through
holes might be arranged in other equivalent manners.
[0063] For example, FIGS. 13 to 15 show a impeller, designated by
the reference numeral 401, which is similar to the impeller 301 but
has through holes 408 that are formed substantially along multiple
arcs which are concentric and centered with respect to the rotation
axis 1000.
[0064] FIGS. 16 to 18 show an impeller, according to the invention,
generally designated by the reference numeral 501, which includes
through holes 508 provided in the second disk element 3, between
pairs of adjacent vanes 4, and arranged substantially along arcs of
a circumference the center of which is arranged outside the
disk.
[0065] In the embodiments shown in FIGS. 4 to 18, the elements that
correspond to the elements that have already been described with
reference to the embodiment shown in FIGS. 1 to 3 have been
designated by the same reference numerals.
[0066] The impeller according to the invention may be manufactured
by means of various techniques, by using metallic materials such
as, for example, steel, stainless steel, die-cast steel, cast iron,
brass, and the like, or other materials provided with the necessary
technological characteristics, such as for example some
techno-polymers.
[0067] Also, it should be noted that the details of construction of
the contoured slots 8 and/or of the through holes 308, 408 or 508
can in any case vary in a substantially equivalent manner in the
shape, dimensions, proportions and arrangements, without however
abandoning the scope of the inventive concept.
[0068] As regards the operation of the impeller according to the
invention, experimental tests and careful analysis of the results
have allowed to observe that the openings provided in the second
disk element 3 entail a higher fluid-dynamics efficiency and a good
head for an equal reduction of axial thrusts.
[0069] In practice it has been found that the impeller for
centrifugal pumps, according to the invention, fully achieves the
intended aim, since it allows to reduce considerably the axial
thrusts but at the same time ensure maximum efficiency and
head.
[0070] In fact, by emptying the areas that are subjected to the
highest pressure in the second disk element, i.e., by forming the
openings, it is possible to reduce the forces that generate the
axial thrust.
[0071] Also, head and efficiency are not reduced because the
profile of these openings is fully included within the second disk
element.
[0072] The impeller according to the present invention therefore
allows to solve the problems linked to the traction that is usually
generated on the transmission shaft of centrifugal pumps with one
or more stages. This allows, for example, to avoid damage to the
bearings of the motor.
[0073] The impeller for centrifugal pumps, and the centrifugal pump
thus conceived are susceptible of numerous modifications and
variations, all of which are within the scope of the inventive
concept; all the details may furthermore be replaced with other
technically equivalent elements.
[0074] In practice, the materials used, so long as they are
compatible with the specific use, as well as the contingent shapes
and dimensions, may be any according to the requirements of the
state of the art.
[0075] This application claims the priority of Italian Patent
Application No. VI2015A000081, filed on Mar. 20, 2015, the subject
matter of which is incorporated herein by reference.
* * * * *