U.S. patent application number 13/002088 was filed with the patent office on 2011-05-26 for centrifugal pump impeller.
This patent application is currently assigned to SHINMAYWA INDUSTRIES, LTD.. Invention is credited to Junya Enomoto, Kazuki Takeuchi, Nobukazu Tanaka, Motonobu Tarui.
Application Number | 20110123337 13/002088 |
Document ID | / |
Family ID | 41465734 |
Filed Date | 2011-05-26 |
United States Patent
Application |
20110123337 |
Kind Code |
A1 |
Tarui; Motonobu ; et
al. |
May 26, 2011 |
CENTRIFUGAL PUMP IMPELLER
Abstract
An impeller include a substantially cylindrical impeller body
with an internal flow path connecting between an inlet opening
through a first end surface and an outlet opening through a
circumferential surface; and a balance weight embedded in the
impeller body. The balance weight has a vertically-elongated shape
in which its height in a cylindrical axis direction is larger than
its thickness in a radial direction. The vertically-elongated
balance weight is embedded in a circumferential section of the
cylindrical impeller body.
Inventors: |
Tarui; Motonobu; (Hyogo,
JP) ; Takeuchi; Kazuki; (Hyogo, JP) ; Enomoto;
Junya; (Hyogo, JP) ; Tanaka; Nobukazu; (Hyogo,
JP) |
Assignee: |
SHINMAYWA INDUSTRIES, LTD.
Hyogo
JP
|
Family ID: |
41465734 |
Appl. No.: |
13/002088 |
Filed: |
July 6, 2009 |
PCT Filed: |
July 6, 2009 |
PCT NO: |
PCT/JP2009/003127 |
371 Date: |
January 7, 2011 |
Current U.S.
Class: |
416/144 |
Current CPC
Class: |
F04D 7/04 20130101 |
Class at
Publication: |
416/144 |
International
Class: |
F04D 29/00 20060101
F04D029/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 4, 2008 |
JP |
2008-175629 |
Claims
1. A centrifugal pump impeller, comprising: an impeller body having
a substantially cylindrical shape with first and second end
surfaces facing each other in a cylindrical axis direction, and
with a circumferential surface interposed between the first and
second end surfaces, and including an internal flow path which
connects between an inlet opening through the first end surface and
an outlet opening through the circumferential surface; and a
balance weight embedded in the impeller body, wherein the balance
weight has a vertically-elongated shape in which its height in the
cylindrical axis direction is larger than its thickness in a radial
direction, and the vertically-elongated balance weight is embedded
in a circumferential section of the cylindrical impeller body.
2. The centrifugal pump impeller of claim 1, wherein one end
section of the impeller body serves as a relatively-thin wear ring
section provided so as to surround the inlet; and the balance
weight is embedded in the wear ring section.
3. The centrifugal pump impeller of claim 2, wherein a lower end
surface of the balance weight embedded in the wear ring section is
exposed in the first end surface of the impeller body, and a
though-hole passing through the balance weight in a thickness
direction or a notch recessed in the lower end surface is formed in
the balance weight; and the impeller body includes a retaining
section of the balance weight, which is formed by filling the
through-hole or the notch of the balance weight with resin when
forming the impeller body by molding.
4. The centrifugal pump impeller of claim 1, wherein a plurality of
positioning holes are formed in the balance weight; and a
positioning pin for positioning the balance weight in a
predetermined section inside a mold when forming the impeller body
by molding is inserted into each of the positioning holes.
Description
TECHNICAL FIELD
[0001] A technique disclosed herein relates to a centrifugal pump
impeller.
BACKGROUND ART
[0002] Conventionally, a centrifugal pump has been used for
delivering, e.g., drainage. Among various impellers attached to the
centrifugal pump, a non-clog impeller in which a flow path
connecting between an inlet opening through a first end surface and
an outlet opening through a circumferential surface is formed has
been known as an impeller in which it is less likely to cause
clogging of, e.g., drainage containing solid substances such as
impurities (see, e.g., Patent Document 1).
[0003] The non-clog impeller has a single vane, and therefore is
formed in non-symmetric shape about a rotation axis. Thus, in the
impeller disclosed in Patent Document 1, a balance weight is
provided in order to achieve static balance at rest and dynamic
balance during rotation in air (hereinafter collectively referred
to as "mechanical balance"), and to achieve balance during rotating
the impeller in water (hydraulic balance). Specifically, in the
impeller disclosed in Patent Document 1, a flat balance weight
extending in a radial direction is attached to each of an upper
surface of an upper flange section and a lower surface of a lower
flange section which outwardly protrude in the radial direction
around an entire circumference, with bolts.
CITATION LIST
[0004] PATENT DOCUMENT 1: Japanese Patent Publication No.
10-238495
SUMMARY OF THE INVENTION
Technical Problem
[0005] Considering reduction in power of a submersible pump, the
diameter of the impeller is desirably reduced. Meanwhile, if the
diameter of particle passing through the impeller (the maximum
diameter of particle which can pass through the flow path) is
increased to enhance particle transmission, the diameter of the
flow path formed in the impeller should be increased. Inventors of
the present invention have recognized that, in order to realize
both of the reduction in power of the submersible pump and the high
particle transmission, the width of the radially-extending
protrusion of the flange section of the impeller should be reduced.
However, if the protrusion width of the flange section is reduced
as described above, there is almost no lower surface region
particularly in the lower flange section. As a result, the balance
weight having a sufficient weight cannot be attached to such a
section.
[0006] The centrifugal pump impeller disclosed herein is an
advantageous impeller for achieving the mechanical balance and the
hydraulic balance by attaching a balance weight to an impeller
body, and realizing the enhancement of the particle transmission by
increasing a flow path diameter and the reduction in power by
reducing an impeller diameter.
Solution to the Problem
[0007] The inventors of the present invention have focused on a
balance weight embedded in an impeller body. An example of a
centrifugal pump impeller includes an impeller body having a
substantially cylindrical shape with first and second end surfaces
facing each other in a cylindrical axis direction, and with a
circumferential surface interposed between the first and second end
surfaces, and including an internal flow path which connects
between an inlet opening through the first end surface and an
outlet opening through the circumferential surface; and a balance
weight embedded in the impeller body. The balance weight has a
vertically-elongated shape in which its height in the cylindrical
axis direction is larger than its thickness in a radial direction,
and the vertically-elongated balance weight is embedded in a
circumferential section of the cylindrical impeller body.
ADVANTAGES OF THE INVENTION
[0008] The vertically-elongated balance weight can be embedded in
the circumferential section of the impeller body, which is
relatively thin in the radial direction. The balance weight is
embedded in the impeller body, and therefore it is not necessary to
attach the balance weight to, e.g., a flange section. That is, by
embedding the balance weight, the mechanical balance and the
hydraulic balance can be achieved, and an increase in flow path
diameter and a reduction in impeller diameter can be simultaneously
realized.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] FIG. 1 is a cross-sectional view of a submersible pump
including a centrifugal pump impeller which is illustrated as an
example.
[0010] FIG. 2 is a perspective view of the impeller.
[0011] FIG. 3 is a front view of the impeller.
[0012] FIG. 4 is a bottom view of the impeller.
[0013] FIG. 5 is a V-V cross-sectional view of FIG. 4.
[0014] FIG. 6 is a plan view of an impeller body in a state in
which a lid is removed.
[0015] FIG. 7 is a view illustrating a back-side surface of the
lid.
[0016] FIG. 8 is a VIII-VIII cross-sectional view of FIG. 7.
[0017] FIG. 9 is an enlarged plan view around a boss section of the
impeller body.
[0018] FIG. 10 is an enlarged cross-sectional view around the boss
section of the impeller body.
[0019] FIG. 11 is a perspective view of an upper balance
weight.
[0020] FIG. 12 is a perspective view of a lower balance weight.
DESCRIPTION OF EMBODIMENTS
[0021] An example of a centrifugal pump impeller includes an
impeller body having a substantially cylindrical shape with first
and second end surfaces facing each other in a cylindrical axis
direction, and with a circumferential surface interposed between
the first and second end surfaces, and including an internal flow
path which connects between an inlet opening through the first end
surface and an outlet opening through the circumferential surface;
and a balance weight embedded in the impeller body. The balance
weight has a vertically-elongated shape in which its height in the
cylindrical axis direction is larger than its thickness in a radial
direction, and the vertically-elongated balance weight is embedded
in a circumferential section of the cylindrical impeller body.
[0022] According to the foregoing configuration, the balance weight
has the vertically-elongated shape. This allows the balance weight
to be embedded in the circumferential section of the impeller body,
which is relatively thin in the radial direction. The balance
weight is embedded in the impeller body, and therefore it is not
necessary to attach the balance weight to, e.g., a flange section.
Thus, an increase in flow path diameter and a reduction in impeller
diameter can be simultaneously realized.
[0023] One end section of the impeller body may serve as a
relatively-thin wear ring section provided so as to surround the
inlet, and the balance weight may be embedded in the wear ring
section.
[0024] The flange section of the impeller body is positioned inside
a volute chamber of a casing, and therefore the balance weight can
be attached to, e.g., an outer circumferential surface of the
flange section. On the other hand, the wear ring section faces a
liner ring of the casing with a slight clearance therebetween, and
therefore the balance weight cannot be attached to, e.g., an outer
circumferential surface of the wear ring section. The configuration
in which the balance weight is embedded in the impeller body is
advantageous particularly when embedding the balance weight in the
wear ring section.
[0025] A lower end surface of the balance weight embedded in the
wear ring section may be exposed in the first end surface of the
impeller body, and a though-hole passing through the balance weight
in a thickness direction or a notch recessed in the lower end
surface may be formed in the balance weight. The impeller body
includes a retaining section of the balance weight, which is formed
by filling the through-hole or the notch of the balance weight with
resin when forming the impeller body by molding.
[0026] There is a possibility that the balance weight is disengaged
during use of the impeller. However, the lower end surface of the
balance weight is exposed in the first end surface of the impeller
body, and therefore the retaining section reduces or prevents such
disengagement. In addition, a simple technique is used, in which
the through-hole or the notch is provided in the balance weight to
form the impeller body by molding. Thus, the disengagement of the
balance weight can be reduced or prevented.
[0027] A plurality of positioning holes may be formed in the
balance weight. A positioning pin for positioning the balance
weight in a predetermined section inside a mold when forming the
impeller body by molding may be inserted into each of the
positioning holes.
[0028] In such a manner, the balance weight is accurately
positioned in the predetermined section inside the mold, thereby
ensuring the balance weight embedded in the circumferential section
of the impeller body.
[0029] An embodiment of the impeller will be described below with
reference to the drawings. Note that the embodiment below has been
set forth merely for purposes of a preferred example in nature.
FIG. 1 illustrates a submersible pump 1 including an impeller which
is illustrated as an example. The submersible pump 1 includes a
pump section 21 with an impeller 6, and a motor section 22 with a
motor 3 for driving the impeller 6. In the submersible pump 1, the
pump section 21 is arranged below an oil casing 23, and the motor
section 22 is arranged above the oil casing 23. That is, the pump
section 21 and the motor section 22 are arranged one above the
other. The submersible pump 1 is a lightweight pump in which a head
cover 34 and a pump casing 4 which will be described later are made
of predetermined resin material.
[0030] The motor section 22 includes the motor 3 with a stator 31
and a rotor 32; a stator casing 33 covering the stator 31 of the
motor 3; and the head cover 34 attached to an upper end of the
stator casing 33. A rotating shaft 35 of the motor 3 vertically
extends.
[0031] The stator casing 33 is formed in substantially cylindrical
shape with upper and lower openings. The upper opening of the
stator casing 33 is closed with a motor cover 36, and a bearing 35a
rotatably supporting an upper end section of the rotating shaft 35
is provided on a lower surface of the motor cover 36.
[0032] The head cover 34 is attached to the upper end of the stator
casing 33. The head cover 34 has an upper wall and a
circumferential wall which downwardly extends from a
circumferential section of the upper wall, and which is fixed to an
upper end section of the stator casing 33. In addition, the head
cover 34 has an inverted U-shaped cross section. Thus, the head
cover 34 and the motor cover 36 defines a housing space 34a in
which various electric components are housed. A cable boot into
which a power feeding cable for feeding power to the motor 3 is
inserted is attached so as to pass through the upper wall of the
head cover 34, and a handle 34b is attached to a center section of
an upper surface of the upper wall. The head cover 34 is fixed to
the oil casing 23 with a plurality of bolts 37 (only one bolt is
illustrated in the figure) arranged at predetermined interval in
the circumferential direction. That is, the bolt 37 inserted into a
through-hole formed in a circumferential section of the head cover
34 passes through the motor cover 36. Then, the bolt 37 downwardly
extends along an inner circumferential surface of the stator casing
33, and is screwed into a circumferential section of the oil casing
23. In such a manner, in the submersible pump 1, the long
vertically-extending bolt 37 fixes the head cover 34, the stator
casing 33, and the motor cover 36 to the oil casing 23 at one time.
Such a configuration allows reduction in the number of components
and the number of assembly steps of the submersible pump 1.
[0033] The oil casing 23 is attached to a lower end of the stator
casing 33, and the lower opening of the stator casing 33 is closed
with the oil casing 23. The pump casing 4 is attached to a lower
side of the oil casing 23, and therefore the oil casing 23 and the
pump casing 4 define an oil chamber 53 filled with lubricating oil.
A through-hole into which the rotating shaft 35 of the motor 3 is
inserted is formed in the oil casing 23, and a bearing 35b
rotatably supporting a middle section of the rotating shaft 35 is
attached to an upper surface of the oil casing 23. In the oil
chamber 53 defined by the oil casing 23 and the pump casing 4, the
rotating shaft 35 is sealed by a mechanical seal 51, and a circular
wall 52 is provided, which surround a substantially entire outer
circumferential section of the mechanical seal 51.
[0034] The pump section 21 includes the impeller 6 attached to a
lower end of the rotating shaft 35 of the motor 3, and the pump
casing 4. The submersible pump 1 is a centrifugal pump. A first
pump casing 41 on an upper side, which defines the oil chamber 53
together with the oil casing 23, and a second pump casing 42 on a
lower side are integrated by welding, thereby forming the pump
casing 4. The first pump casing 41 and the second pump casing 42
are integrated by welding as described above, and therefore a
flange is not required, which is required, e.g., when integrating
two pump casings with a bolt-nut fastening means. Consequently, the
size of the submersible pump 1 is reduced.
[0035] A through-hole into which the rotating shaft 35 is inserted
is formed in an upper section of the pump casing 4, and a volute
chamber 43 in which the impeller 6 is housed is formed inside the
pump casing 4. The pump casing 4 has a lower opening, and a liner
ring 44 with an opening 44a, which supports a wear ring section 692
which is a lower end section of the impeller 6 is attached to such
an opening. A discharge section 45 which laterally protrudes, and
which is upwardly curved is integrally formed with a side section
of the pump casing 4. The discharge section 45 communicates with
the volute chamber 43, and has a discharge port 45a with an upper
opening. The discharge port 45a is connected to an outlet pipe
which is not shown in the figure. Four downwardly-extending legs 46
(only three legs 46 are illustrated in FIG. 1) are arranged in a
lower section of the pump casing 4 in a predetermined pattern, and
lower ends of the legs 46 are attached and fixed to a seat 7. The
seat 7 includes a body section 71 made of synthetic resin; and a
cover 72 which covers a lower side of the body section 71, and
which is made of rubber. Inserting sections 73 into which the lower
ends of the legs 46 are inserted, and in which the lower ends of
the legs 46 are fastened with screws are integrally formed with the
body section 71 so as to upwardly protrude. A damping rubber member
or damping steel plate 74 is interposed between a lower surface of
the leg 46 and the inserting section 73. The seat 7 functions to
reduce or prevent displacement of a position where the submersible
pump 1 is arranged due to the cover 72, and to control vibration by
the damping rubber member or damping steel plate 74 when driving
the submersible pump 1.
[0036] As illustrated in FIGS. 2-5, the impeller 6 is a non-clog
impeller having a substantially cylindrical shape, and is fixed to
the lower end of the rotating shaft 35 so that a cylindrical axis
of the impeller 6 is coaxial to the rotating shaft 35 (see FIG. 1).
The impeller 6 includes an impeller body 61, and a lid 62 attached
to an upper end surface of the impeller body 61. In addition, in
order to achieve mechanical and hydraulic balance, the impeller 6
also includes an upper balance weight 63 and a lower balance weight
64. Although details will be described later, the upper balance
weight 63 is arranged and fixed between the impeller body 61 and
the lid 62, and the lower balance weight 64 is embedded in the wear
ring section 692 of the impeller body 61 as illustrated in FIG.
5.
[0037] The impeller body 61 has a substantially cylindrical shape.
An inlet 601 opening at the bottom of the impeller body 61 is
formed in a lower end surface of the impeller body 61, and an
outlet 602 opening through a side of the impeller body 61 is formed
in a predetermined section of a circumferential surface of the
impeller body 61. An internal flow path 603 extending in the
cylindrical axis direction is formed inside the impeller 6, and the
internal flow path 603 connects between the inlet 601 and the
outlet 602. An external flow path 604 inwardly recessed in the
radial direction is formed in an outer circumferential surface of
the impeller body 61. The external flow path 604 is not a flow path
extending in the cylindrical axis direction, and the center of the
flow path is positioned on a plane perpendicular to the cylindrical
axis of the impeller body 61. The external flow path 604 reaches a
downstream side of the internal flow path 603 at the outlet 602,
and extends across a substantially entire perimeter of the impeller
6. The external flow path 604 is defined by a vane 605. The vane
605 is a so-called "single radial-flow vane (centrifugal vane), and
the centrifugal vane 605 increases the pressure of water in the
external flow path 604, and then discharges such water to an outer
circumferential side (outer side in the radial direction). A first
flange section 681 outwardly protruding in the radial direction
around an entire circumference is formed above the external flow
path 604 of the impeller body 61. In addition, a second flange
section 682 outwardly protruding in the radial direction around the
entire circumference is also formed below the external flow path
604. The second flange section 682 horizontally divides the
impeller 6 into a lower section where the inlet 601 is formed, and
an upper section where the outlet 602 is formed. That is, the
impeller 6 is a closed-type impeller in which the second flange
section 682 divides between the inlet 601 and the outlet 602.
[0038] A shaft support section 691 is formed so as to upwardly
protrude in the center of the upper end surface of the impeller
body 61, which is above the first flange section 681. The shaft
support section 691 is made of predetermined metal material, and is
provided with an attachment hole into which the rotating shaft 35
of the motor 3 is inserted to be fixed. In addition, the
downwardly-protruding wear ring section 692 inserted into the
opening 44a of the pump casing 4 is formed below the second flange
section 682 of the impeller body 61.
[0039] In order to reduce power of the submersible pump 1, the
first and second flange sections 681 and 682 are set to a smaller
diameter so that the diameter of the impeller body 61 becomes as
small as possible. Thus, as illustrated in FIGS. 3 and 5, the
impeller body 61 is designed with almost no step between the second
flange section 682 and the wear ring section 692. The diameters of
the first and second flange sections 681 and 682 may be further
reduced in order to, e.g., eliminate such a step. Conversely, the
diameter of the wear ring section 692 is increased so that the
diameter of the inlet 601 is increased, thereby eliminating the
step between the second flange section 682 and the wear ring
section 692.
[0040] The impeller body 61 is made of synthetic resin. As
illustrated in FIGS. 5 and 6, a recessed section 611 recessed in
the cylindrical axis direction in the upper end surface of the
impeller body 61 is formed in order to reduce or prevent shrinkage
caused when forming the impeller due to the substantially constant
thickness of the impeller. As illustrated in FIG. 6, the recessed
section 611 extends substantially three-fourths of the entire
perimeter from an opening side of the outlet 602 (upper side as
viewed in FIG. 6), in the counterclockwise and circumferential
directions. In addition, as illustrated in FIG. 5, the recessed
section 611 is formed so that the depth is relatively shallow on
the opening side of the outlet 602 (right side as viewed in FIG.
5), and the depth is relatively deep on a side opposite to the
opening side of the outlet 602 (left side as viewed in FIG. 5).
[0041] Reinforcement ribs 612 extending in the radial direction,
and connecting between the shaft support section 691 and a
circumferential section of the impeller body 61 are formed in an
upper end section of the impeller body 61. In the present
embodiment, in the impeller body 61 illustrated in FIG. 6, three
reinforcement ribs 612 are formed at predetermined angles in an
upper half region corresponding to the opening side of the outlet
602, and a single reinforcement rib 612 is formed in a lower half
region corresponding to the side opposite to the opening side of
the outlet 602. Three of the four reinforcement ribs 612 are
arranged inside the recessed section 611. As illustrated in, e.g.,
FIG. 10, the three reinforcement ribs 612 arranged on the opening
side of the outlet 602 are also used as a mounting section on which
the upper balance weight 63 is mounted. That is, an upper end
surface of each of the reinforcement ribs 612 serves as a mounting
surface 614 on which the upper balance weight 63 is mounted.
Further, a boss section 613 for fixing the upper balance weight 63
is formed in the substantially center of the reinforcement rib 612
in the radial direction.
[0042] As illustrated in FIGS. 9 and 10, the boss section 613 is
formed in circular shape as viewed in plan, which has a diameter
larger than the width of the reinforcement rib 612. An
upwardly-opening pinhole 615 which extends in the cylindrical axis
direction is formed in the center of the boss section 613. In an
outer circumferential surface of the boss section 613, three
protrusions 616 outwardly protruding in the radial direction are
integrally formed with the boss section 613 at equal interval in
the circumferential direction.
[0043] As illustrated in FIG. 11, the upper balance weight 63 made
of predetermined metal material is formed in substantially fan-like
shape by cutting a section corresponding to a predetermined angular
range from an annular disk-like member having a predetermined
thickness. The upper balance weight 63 has a flattened shape in
which the width of the upper balance weight 63 in the radial
direction is larger than the thickness of the upper balance weight
63 in the cylindrical axis direction (vertical direction). As
illustrated in FIG. 6, the upper balance weight 63 is arranged
between the shaft support section 691 and the circumferential
section of the impeller body 61. Thus, the inner diameter of the
upper balance weight 63 is set so as to be larger than the diameter
of the shaft support section 691, and the outer diameter of the
upper balance weight 63 is set so as to be smaller than the
diameter of the circumferential section of the impeller body 61.
The shape of the upper balance weight 63 is not limited, and may be
suitably set so that a required weight can be ensured under a
condition where the upper balance weight 63 is arranged between the
impeller body 61 and the lid 62. In the upper balance weight 63,
three holes 631 passing through the upper balance weight 63 in a
thickness direction are formed corresponding to the three boss
sections 613. Each of such holes is a fitting hole 631 fitted onto
the boss section 613. As hypothetically illustrated in FIG. 9, the
diameter of such a hole is set so as to be larger than that of the
boss section 613, and to be smaller than that of a circle defined
by connecting tip ends of the protrusions 616.
[0044] As illustrated in enlarged views of FIGS. 9 and 10, the
upper balance weight 63 is mounted on the mounting surface 614 of
the reinforcement rib 612 so that each of the fitting holes 631 is
fitted onto the boss section 613. Thus, the upper balance weight 63
is positioned in a predetermined section of the upper end surface
of the impeller body 61 on the opening side of the outlet 602. The
fitting hole 631 of the upper balance weight 63 is set so as to
have the diameter larger than that of the boss section 613, and
smaller than that of the circle defined by connecting the tip ends
of the protrusions 616. Thus, a part of the protrusions 616 is
pressed against the boss section 613, thereby fitting the fitting
hole onto the boss section 613. This reduces the rattling of the
upper balance weight 63.
[0045] As illustrated in FIGS. 7 and 8, the lid 62 has a circular
disk-like shape, and a through-hole 621 into which the shaft
support section 691 of the impeller body 61 is inserted is formed
in the center of the lid 62. The lid 62 is made of synthetic rein.
A front-side surface of the lid 62 is flat. On each of a side
corresponding to the opening of the outlet 602 and its opposite
side with respect to the cylindrical axis in the circumferential
section of the lid 62, two engagement claws 622 are integrally
formed with the lid 62 at predetermined interval in the
circumferential direction. The engagement claw 622 is a claw to be
engaged with an engagement groove 683 formed at a circumference of
the upper end section of the impeller body 61, and the engagement
claw 622 and the engagement groove 683 serve as an engagement means
for attaching and fixing the lid 62 to the impeller body 61.
[0046] In positions of a back-side surface of the lid 62
corresponding to the boss sections 613 of the impeller body 61,
three pins 623 are formed so as to protrude from the back-side
surface. As illustrated in FIG. 10, when attaching the lid 62 to
the impeller body 61, each of the pins 623 is fitted into the
pinhole 615 formed in the boss section 613. In addition to the
engagement of the engagement claw 622 with the engagement groove
683, the fitting of the pin 623 into the pinhole 615 allows the lid
62 to be more stably attached and fixed to the impeller body 61.
Holding sections 624 for holding the upper balance weight 63 are
further formed so as to protrude from the back-side surface of the
lid 62. The holding section 624 is formed in circular shape so as
to surround the pin 623. As illustrated in FIG. 10, when attaching
and fixing the lid 62 to the impeller body 61, a lower surface of
the holding section 624 downwardly presses against an upper surface
of the upper balance weight 63 around the boss section 613. Thus,
the upper balance weight 63 is sandwiched between the lid 62 and
the impeller body 61.
[0047] In the lid 62, two through-holes 625 are formed on each of
the opening side of the outlet 602 and its opposite side. Such
through-holes are air vent holes 625 through which air is vented
from the recessed section 611 of the impeller body 61 to fill the
recessed section 611 with water. Air vent holes may be formed in
the upper balance weight 63. In such a case, such air vent holes
are desirably formed in the same positions as those of the air vent
holes 625 formed in the lid 62. The air vent holes 625 are provided
in the lid 62 to fill the recessed section 611 with water as
described above. Thus, this reduces or prevents a loss of
mechanical balance of the impeller 6 due to remaining air in the
recessed section 611, and reduces occurrence of vibration when
driving the impeller 6.
[0048] As illustrated in FIGS. 3 and 4, the lower balance weight 64
is embedded in the wear ring section 692 on the opening side of the
outlet 602 of the impeller body 61. As illustrated in, e.g., FIG.
12, the lower balance weight 64 made of predetermined metal
material is a plate curved in arc, and has a vertically-elongated
shape in which a height in the cylindrical axis direction is larger
than a thickness in the radial direction. As illustrated in FIG. 4,
the lower balance weight 64 is embedded in the wear ring section
692 so that a lower end surface of the lower balance weight 64 is
exposed in the lower end surface of the impeller body 61. Two
through-holes 641 are formed in predetermined positions of the
lower balance weight 64, and each through-hole 641 serves as a
positioning hole into which a positioning pin 8 of a mold is
inserted. A notch 642 is formed in a center section of a lower end
of the lower balance weight 64. When forming the impeller body 61
by molding, a section corresponding to the notch 642 is filled with
resin, and therefore a retaining section 694 is formed, which
crosses the lower balance weight 64 in the thickness direction as
illustrated in FIG. 4.
[0049] Next, a manufacturing process of the impeller body 61 will
be briefly described. First, the shaft support section 691 and the
lower balance weight 64 are arranged in predetermined positions
inside the mold (not shown in the figure). In such a state, a
position of the lower balance weight 64 in the circumferential
direction, and an inclination of the lower balance weight 64 are
determined by the two positioning pins 8 as illustrated in FIG. 12.
The positioning pin 8 includes a small-diameter section 81 on a tip
end side, and a large-diameter section 82 on a base end side. A
position of the lower balance weight 64 in the radial direction is
also determined by a position of a step defined by such sections
having the different diameters. In such a manner, the lower balance
weight 64 can be accurately positioned in a predetermined section
inside the mold, thereby ensuring the lower balance weight 64
embedded in the thin wear ring section 692 of the impeller body
61.
[0050] Then, the impeller body 61 is formed by a well-known resin
molding. As illustrated in FIGS. 2 and 3, holes 693 are formed in
the wear ring section 692 of the molded impeller body 61 by the
positioning pins 8.
[0051] Next, the separately-prepared upper balance weight 63 is
attached to the upper end surface of the molded impeller body 61.
As described above, in the upper balance weight 63, the fitting
hole 631 of the upper balance weight 63 is fitted onto the boss
section 613 with the protrusions 616 of the boss section 613 being
pressed against the fitting hole 631.
[0052] Subsequently, the separately-molded lid 62 is attached to
the impeller body 61. In such a state, the pin 623 of the lid 62 is
fitted into the pinhole 615 of the impeller body 61, and the
engagement claw 622 of the lid 62 is elastically deformed to be
engaged with the engagement groove 683 of the impeller body 61.
When attaching and fixing the lid 62 to the impeller body 61, the
holding sections 624 of the lid 62 press against the upper balance
weight 63. Thus, attachment of the upper balance weight 63 to the
impeller body 61 is completed.
[0053] As described above, in the impeller 6 having the foregoing
configuration, the fastening means such as bolts is not used to fix
the lid 62 to the impeller body 61, and the engagement claws 622
are engaged with the engagement grooves 683 to attach and fix the
lid 62 to the impeller body 61. Thus, tools etc. are not required
for the assembly process, and the assembly of the impeller 6 is
simplified. In addition, when attaching the lid 62 to the impeller
body 61, the upper balance weight 63 is fixed to the impeller body
61.
[0054] Consequently, the assembly process of the impeller 6 is
further facilitated.
[0055] The engagement claws 622 are provided in the lid 62, and the
engagement grooves 683 opening toward outside are provided in the
circumferential section of the impeller body 61. Thus, in a state
in which the lid 62 is attached to the impeller body 61, the
engagement sections are not protrude from the front-side surface of
the lid 62, thereby ensuring the flat surface at the upper end of
the impeller 6. This is advantageous to reduce a power loss. Note
that engagement grooves may be provided in the lid 62, and
engagement claws may be provided in the impeller body 61. The
engagement section where the lid 62 is engaged with the impeller
body 61 is not limited to the combination of the engagement claw
622 and the engagement groove 683, and any configuration may be
employed.
[0056] The circumferential section of the lid 62 is fixed to the
impeller body 61 by the engagement claws 622 and the engagement
grooves 683, and the pins 623 provided in the lid 62 are fitted
into the pinholes 615 of the impeller body 61. Thus, an inner
section of the lid 62 in the radial direction can be fixed to the
impeller body 61. Consequently, the inner section of the lid 62 in
the radial direction is not apart from the impeller body 61.
[0057] The fitting hole 631 of the upper balance weight 63 is
fitted onto the boss section 613 of the impeller body 61. Thus, the
upper balance weight 63 can be correctly positioned on the
predetermined section of the impeller body 61, and the occurrence
of the rattling of the upper balance weight 63 can be reduced or
prevented.
[0058] The reinforcement rib 612 improves the strength of the
impeller body 61 itself. In addition, the upper balance weight 63
and the boss section 613 used for the fixing of the lid are
integrally formed with the reinforcement rib 612, thereby improving
the stiffness of the boss section 613. This is advantageous to more
stably fix the upper balance weight 63 and the lid 62 to the
impeller body 61.
[0059] Unlike the upper balance weight 63, the lower balance weight
64 has the vertically-elongated shape, thereby embedding the lower
balance weight 64 in the wear ring section 692 which is thin in the
radial direction. The lower balance weight 64 is embedded in the
impeller body 61, and therefore it is not necessary to attach the
balance weight to the second flange section 682. This allows the
diameter of the inlet 601 of the impeller 6 to be as large as
possible, thereby ensuring predetermined substance passage
properties. In addition, the diameters of the first and second
flange sections 681 and 682 become as small as possible in order to
reduce the diameter of the impeller 6, thereby reducing the power
of the submersible pump 1.
[0060] The lower end surface of the lower balance weight 64
embedded in the wear ring section 692 is exposed in the lower end
surface of the impeller body 61, and therefore there is a
possibility that the lower balance weight 64 is disengaged during
use of the impeller 6. However, the retaining section 694 is
configured by forming the notch 642 at the lower end of the lower
balance weight 64, thereby reducing or preventing the disengagement
of the lower balance weight 64. In the present embodiment, the
retaining section 694 is configured by forming the notch 642 at the
lower end of the lower balance weight 64. However, a through-hole
passing through the lower balance weight 64 in the thickness
direction may be formed in, e.g., a middle section of the lower
balance weight 64 in the height direction, thereby forming a resin
retaining section crossing the lower balance weight 64 in the
thickness direction. Alternatively, the entire lower balance weight
64 may be embedded in the impeller body 61, and therefore the lower
end of the lower balance weight 64 may not be exposed. In such a
case, the retaining section is not required.
[0061] In the foregoing embodiment, the lower balance weight 64 is
embedded in the wear ring section 692. However, e.g., if the height
of the lower balance weight 64 is increased under a condition where
the required weight is ensured, an upper end section of the lower
balance weight 64 may be positioned corresponding to the second
flange section 682.
[0062] The lower balance weight 64 is not limited to the
configuration in which the lower balance weight 64 is embedded in
the wear ring section 692, and the lower balance weight 64 may be
embedded in any parts of the circumferential section of the
impeller body 61.
[0063] The impeller is not limited to the impeller made of
synthetic resin.
DESCRIPTION OF REFERENCE CHARACTERS
[0064] 1 Submersible Pump [0065] 6 Impeller [0066] 601 Inlet [0067]
602 Outlet [0068] 603 Internal Flow Path [0069] 61 Impeller Body
[0070] 64 Lower Balance Weight [0071] 641 Positioning Hole [0072]
642 Notch [0073] 692 Wear Ring Section [0074] 694 Retaining Section
[0075] 8 Positioning Pin
* * * * *