Note: Descriptions are shown in the official language in which they were submitted.
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DESCRIPTION
CENTRIFUGAL PUMP IMPELLER
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, a part of the impeller disclosed in Patent
Document I is
removed in order to achieve static balance at rest and dynamic balance during
rotation in air
(hereinafter collectively referred to as "mechanical balance"). In a second
end surface of the
substantially cylindrical impeller, which is on an opposite side to the first
end surface in
which the inlet is formed, such removal allows formation of a recessed section
which opens
through the second end surface, and which is recessed in a cylindrical axis
direction in the
second end surface. As in the foregoing impeller, in an impeller made of
synthetic resin, a
recessed section which opens through a second end surface, and which is
recessed in a
cylindrical axis direction in the second end surface may be formed in order to
reduce or
prevent shrinkage caused when forming the impeller due to the substantially
constant
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thickness of the impeller.
[0004] However, the opening of the recessed section is exposed, resulting in a
power loss
due to fluid turbulence. Thus, in the impeller disclosed in Patent Document 1,
a lid is
attached to the second end surface, and the opening of the recessed section is
covered by the
lid. Consequently, the flat second end surface of the impeller is defined.
CITATION LIST
PATENT DOCUMENT
[0005] PATENT DOCUMENT 1: Japanese Patent Publication No. 2006-291937
SUMMARY OF THE INVENTION
TECHNICAL PROBLEM
[0006] In the conventional impeller disclosed in Patent Document 1, the lid is
fixed to an
impeller body with bolts. Thus, its assembly process is complicated. In
addition, in the
impeller disclosed in Patent Document 1, a balance weight is attached to a
back-side surface
of the lid with the bolts in order to achieve the mechanical balance and
balance during
rotating the impeller in water (hydraulic balance). Thus, there is a
disadvantage that not
only a lid attachment process but also a balance weight attachment process are
separately
required.
[0007] The centrifugal pump impeller disclosed herein is an advantageous
impeller for
simplifying an attachment structure of a lid attached to an impeller body, and
simplifying an
assembly process.
SOLUTION TO THE PROBLEM
[0008] Inventors of the present invention have focused on an engagement
structure
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between an impeller body and a lid; and have arrived at a configuration in
which an
engagement between the impeller body and the lid is facilitated through an
engagement
section, and a balance weight is sandwiched between the lid engaged with the
impeller body
and the impeller body to fix the balance weight to the impeller body.
[0009] 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 in the first end surface and an outlet opening in the circumferential
surface, and a
recessed section which opens in the second end surface, and which is recessed
in the
cylindrical axis direction in the second end surface; a lid which is attached
to the second end
surface of the impeller body, and which covers the opening of the recessed
section so that the
second end surface of the impeller body defines a flat surface; and a balance
weight arranged
between the impeller body and the lid. The lid is attached and fixed to the
impeller body
through an engagement section, and holding sections of the balance weight are
formed in a
back-side surface. When the lid is attached and fixed to the impeller body,
the balance
weight is sandwiched between the holding section of the lid and the impeller
body, and is
fixed by the holding section of the lid and the impeller body.
ADVANTAGES OF THE INVENTION
[0010] According to the foregoing configuration, the lid is attached and fixed
to the
impeller body through the engagement section. By attaching and fixing the lid
to the
impeller body, the balance weight is sandwiched between the holding section of
the lid and
the impeller body, and then the balance weight is attached and fixed to the
impeller body.
That is, the lid and the balance weight are simultaneously attached to the
impeller body,
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thereby simplifying an assembly process of the impeller.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] [FIG. 1] FIG. 1 is a cross-sectional view of a submersible pump
including a
centrifugal pump impeller which is illustrated as an example.
[FIG. 2] FIG. 2 is a perspective view of the impeller.
[FIG. 3] FIG. 3 is a front view of the impeller.
[FIG. 4] FIG. 4 is a bottom view of the impeller.
[FIG. 5] FIG. 5 is a V-V cross-sectional view of FIG. 4.
[FIG. 6] FIG. 6 is a plan view of an impeller body in a state in which a lid
is
removed.
[FIG. 7] FIG. 7 is a view illustrating a back-side surface of the lid.
[FIG. 8] FIG. 8 is a VIII-VIII cross-sectional view of FIG. 7.
[FIG. 9] FIG. 9 is an enlarged plan view around a boss section of the impeller
body.
[FIG. 10] FIG. 10 is an enlarged cross-sectional view around the boss section
of
the impeller body.
[FIG. 11] FIG. 11 is a perspective view of an upper balance weight.
[FIG. 12] FIG. 12 is a perspective view of a lower balance weight.
DESCRIPTION OF EMBODIMENTS
[0012] 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
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opening in the first end surface and an outlet opening in the circumferential
surface, and a
recessed section which opens in the second end surface, and which is recessed
in the
cylindrical axis direction in the second end surface; a lid which is attached
to the second end
surface of the impeller body, and which covers the opening of the recessed
section so that the
second end surface of the impeller body defines a flat surface; and a balance
weight arranged
between the impeller body and the lid. The lid is attached and fixed to the
impeller body
through an engagement section, and holding sections of the balance weight are
formed in a
back-side surface. When the lid is attached and fixed to the impeller body,
the balance
weight is sandwiched between the holding section of the lid and the impeller
body, and is
fixed by the holding section of the lid and the impeller body.
[0013] The lid is attached and fixed to the impeller body through the
engagement section,
thereby sandwiching the balance weight between the holding section of the lid
and the
impeller body. Consequently, the balance weight is attached and fixed to the
impeller body.
As described above, the lid and the balance weight are simultaneously attached
to the impeller
body, thereby facilitating an assembly process of the impeller.
[0014] The engagement section may include engagement grooves formed in the
impeller
body or the lid; and engagement claws which are formed in the lid or the
impeller body, and
which are engaged with the engagement grooves by elastically deforming when
attaching the
lid to the impeller body.
[0015] The engagement groove and the engagement claw can be engaged with each
other
without using, e.g., tools. Thus, the tools etc. are not required when
attaching the lid to the
impeller body, thereby further simplifying the assembly process of the
impeller.
[0016] A plurality of pins may be formed so as to protrude from the back-side
surface of
the lid; and a plurality of pinholes into which the pins are fitted may be
formed so as to open
through the second end surface of the impeller body.
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[0017] Positions of the pin and the pinhole are adjusted to each other, and
the position of
the lid is determined on the impeller body. In combination with the engagement
in the
engagement section, the fitting of the pin into the pinhole allows the lid to
be more firmly
fixed to the impeller body.
[0018] Each of the pinholes may be formed in a boss section provided in the
second end
surface of the impeller body. A plurality of protrusions may be formed with
spacing in a
circumferential direction in a circumferential surface of the boss section.
Fitting holes
which have a larger diameter than that of the boss section, and which have a
smaller diameter
than that of a circle defined by connecting tip ends of the plurality of
protrusions may be
formed in the balance weight; and, in order to fix the balance weight to the
impeller body,
the fitting holes of the balance weight may be fitted onto the boss sections
with the
protrusions being pressed against the boss sections. The holding section of
the lid is formed
in circular shape so as to surround the pin, and holds the balance weight in a
section around
the fitting hole.
[0019] The fitting hole of the balance weight is fitted onto the boss section
of the impeller
body, and therefore the balance weight can be correctly positioned on a
predetermined section
of the impeller body. In addition, the fitting hole of the balance weight is
fitted onto the boss
section of the impeller body, and the holding section of the lid presses
against the section
around the fitting hole. This reduces or prevents occurrence of rattling of
the balance
weight, and firmly fixes the balance weight to the impeller body.
[0020] A plurality of reinforcement ribs extending in a radial direction may
be formed
inside the recessed section of the impeller body, and an end surface of the
reinforcement rib
in the cylindrical axis direction may be a mounting surface on which the
balance weight is
mounted. The boss section may be integrally formed with the reinforcement rib
in the
mounting surface of the reinforcement rib.
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[0021] The reinforcement rib improves a strength of the impeller body. In
addition, the
boss section is integrally formed with the reinforcement rib, thereby
improving stiffness of the
boss section. The balance weight is more stably fixed to the impeller body.
[0022] 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. I illustrates a submersible pump I 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.
[0023] 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.
[0024] 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.
[0025] 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
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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.
[0026] 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.
[0027] 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
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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 l is reduced.
[0028] 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.
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[0029] 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.
[0030] 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
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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.
[0031] 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.
[0032] 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.
[0033] 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,
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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).
[0034] 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.
[0035] 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.
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[0036] 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.
[0037] 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
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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.
[0038] 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.
[0039] 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
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the impeller body 61.
[0040] 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.
[0041] 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.
[0042] Next, a manufacturing process of the impeller body 61 will be briefly
described.
CA 02729815 2010-12-31
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.
[0043] 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.
[0044] 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 63 1.
[0045] 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.
[0046] As described above, in the impeller 6 having the foregoing
configuration, the
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CA 02729815 2010-12-31
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.
Consequently, the assembly process of the impeller 6 is further facilitated.
[0047] 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.
[0048] 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.
[00491 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.
[0050] The reinforcement rib 612 improves the strength of the impeller body 61
itself. In
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CA 02729815 2010-12-31
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.
[0051] 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.
[0052] 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
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CA 02729815 2010-12-31
case, the retaining section is not required.
[0053] 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.
[0054] 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.
[0055] The impeller is not limited to the impeller made of synthetic resin.
DESCRIPTION OF REFERENCE CHARACTERS
1 Submersible Pump
6 Impeller
601 Inlet
602 Outlet
603 Internal Flow Path
61 Impeller Body
611 Recessed Section
612 Reinforcement Rib
613 Boss Section
615 Pinhole
616 Protrusion
62 Lid
622 Engagement Claw
623 Pin
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CA 02729815 2010-12-31
624 Holding Section
63 Upper Balance Weight
631 Fitting Hole
683 Engagement Groove
