U.S. patent application number 15/505284 was filed with the patent office on 2017-09-21 for impeller for fluid pump.
This patent application is currently assigned to TBK Co., Ltd.. The applicant listed for this patent is TBK Co., Ltd.. Invention is credited to Satoshi Nagao, Makoto Osawa, Jea woong Seok.
Application Number | 20170268526 15/505284 |
Document ID | / |
Family ID | 55398877 |
Filed Date | 2017-09-21 |
United States Patent
Application |
20170268526 |
Kind Code |
A1 |
Seok; Jea woong ; et
al. |
September 21, 2017 |
IMPELLER FOR FLUID PUMP
Abstract
An impeller (100) for a fluid pump according to the present
invention comprises a shroud (150) that has a disk shape and is
drivingly rotated about a center axis, and a cover (110) comprising
a cover main body (120) having a truncated cone shape with an inlet
port (123) for a fluid formed at a center and a plurality of blades
(130) arranged around a center axis of the cover main body (120).
The cover (110) and the shroud (150) are joined to each other with
a welding contacting portion (135) and a welding contacted portion
(177) welded to each other in a center axis direction, in a state
where another end surface of the shroud (150) and a distal end
portion (131) of the blades (130) are in parallel with each
other.
Inventors: |
Seok; Jea woong;
(Machida-shi, JP) ; Nagao; Satoshi;
(Hiratsuka-shi, JP) ; Osawa; Makoto;
(Yokohama-shi, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
TBK Co., Ltd. |
Machida-shi Tokyo |
|
JP |
|
|
Assignee: |
TBK Co., Ltd.
Machida-shi Tokyo
JP
|
Family ID: |
55398877 |
Appl. No.: |
15/505284 |
Filed: |
August 28, 2014 |
PCT Filed: |
August 28, 2014 |
PCT NO: |
PCT/JP2014/004421 |
371 Date: |
February 21, 2017 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F04D 29/242 20130101;
F04D 29/4293 20130101; F04D 29/2216 20130101; F04D 29/2222
20130101; F05D 2230/232 20130101; F04D 29/24 20130101 |
International
Class: |
F04D 29/22 20060101
F04D029/22; F04D 29/42 20060101 F04D029/42; F04D 29/24 20060101
F04D029/24 |
Claims
1. An impeller for a fluid pump, the impeller comprising: an
impeller main body member that has a disk shape and is drivingly
rotated about a center axis; and an impeller cover member
comprising: a cover main body having a truncated cone shape with an
inlet port for a fluid formed at a center; and a plurality of
blades arranged around a center axis of the cover main body,
wherein the impeller main body member and the impeller cover member
face each other in a center axis direction, the cover main body
comprises an inclined portion extending toward the impeller main
body member in the center axis direction, while being inclined
toward an outer side in a radial direction, the plurality of blades
are disposed on a side of the inclined portion facing the impeller
main body member, the blades each have a distal end portion, facing
the impeller main body member in the center axis direction,
provided with a welding contacting portion, the impeller main body
member comprises: one end surface facing the impeller cover member;
another end surface disposed on an opposite side of the one end
surface in the center axis direction; groove portions that are
formed at positions matching the blades on the one end surface, and
receive the distal end portions of the blades; and a welding
contacted portion that is formed in the groove portions and is
capable of coming into contact with the welding contacting portion,
and the impeller main body member and the impeller cover member are
joined to each other with the welding contacting portion and the
welding contacted portion welded to each other in the center axis
direction, in a state where the other end surface of the impeller
main body member and the distal end portion of the impeller cover
member are in parallel with each other.
2. The impeller for a fluid pump according to claim 1, wherein the
blades each comprise: the distal end potion; a first outer surface
continuing to a rear side of the distal end portion in a rotation
direction; and a second outer surface continuing to a front side of
the distal end portion in the rotation direction, the groove
portions each comprise: a groove bottom portion that faces the
distal end portion in a center axis direction; a first inner
surface that continues to a rear side of the groove bottom portion
in the rotation direction, and comes into contact with the first
outer surface; and a second inner surface that continues to a front
side of the groove bottom portion in the rotation direction, and
faces the first inner surface, the welding contacting portion is
formed in a corner portion between the distal end portion and the
second outer surface of the corresponding blade, and the welding
contacted portion, as an inclined surface, is formed on the second
inner surface of the groove portion.
Description
TECHNICAL FIELD
[0001] The present invention relates to an impeller used in a fluid
pump examples of which including a water pump.
TECHNICAL BACKGROUND
[0002] Centrifugal fluid pumps have conventionally been known in
which a fluid, sucked in from an inlet port by rotating an impeller
with a plurality of blades formed thereon, is pressurized and then
is discharged through a discharge port. The impeller includes an
open impeller and a closed impeller. The open impeller includes a
disk portion provided on only one end portion of the blade, whereas
the closed impeller includes the disk portions provided on both end
portions to sandwich the blade from both sides (see, for example,
Patent Document 1). The closed impeller incorporates a closed space
defined by both disk portions to prevent the fluid from flowing
out, and thus can be regarded as having a higher pump efficiency
than the open impeller.
PRIOR ARTS LIST
Patent Document
[0003] Patent Document 1: Japanese Laid-Open Patent Publication No.
2011-252481(A)
SUMMARY OF THE INVENTION
Problems to be Solved by the Invention
[0004] The closed impeller has the configuration featuring a shape
with both ends of the blades coupled with each other via the disk
portions. Thus, when the closed impeller is integrally molded as an
injection molded member for example, demolding involves what is
known as an undercut portion making the mass production difficult.
In view of this, in recent years, it has been a common practice to
form an integral closed impeller with one disk portion and the
other disk portion, with the plurality of blades formed thereon,
separately molded, and then joined together via the plurality of
blades. However, this technique has a problem in that an impeller
with sufficient joining strength is difficult to form.
[0005] The present invention is made in view of the problem
described above, and an object of the present invention is to
provide an impeller, for a fluid pump, having a simple structure
that can achieve high joining strength.
Means to Solve the Problems
[0006] To solve the problem described above, an impeller for a
fluid pump according to the present invention comprises an impeller
main body member that has a disk shape and is drivingly rotated
about a center axis; and an impeller cover member comprising: a
cover main body having a truncated cone shape with an inlet port
for a fluid formed at a center; and a plurality of blades arranged
around a center axis of the cover main body. The impeller main body
member and the impeller cover member face each other in a center
axis direction. The cover main body comprises an inclined portion
extending toward the impeller main body member in the center axis
direction, while being inclined toward an outer side in a radial
direction. The plurality of blades are disposed on a side of the
inclined portion facing the impeller main body member. The blades
each have a distal end portion, facing the impeller main body
member in the center axis direction, provided with a welding
contacting portion. The impeller main body member comprises: one
end surface facing the impeller cover member; another end surface
disposed on an opposite side of the one end surface in the center
axis direction; groove portions that are formed at positions
matching the blades on the one end surface, and receive the distal
end portions of the blades; and a welding contacted portion that is
formed in the groove portions and is capable of coming into contact
with the welding contacting portion. The impeller main body member
and the impeller cover member are joined to each other with the
welding contacting portion and the welding contacted portion welded
to each other in the center axis direction, in a state where the
other end surface of the impeller main body member and the distal
end portion of the impeller cover member are in parallel with each
other. The entire distal end portions of the blades are not
necessarily in parallel with the other end surface of the impeller
main body member, and it is sufficient if at least a part of the
welding contacting portions of the distal end portions of the
blades is in parallel with the other end surface of the impeller
main body member.
[0007] Preferably, in the impeller for a fluid pump according to
the present invention, the blades each comprise: the distal end
potion; a first outer surface continuing to a rear side of the
distal end portion in a rotation direction; and a second outer
surface continuing to a front side of the distal end portion in the
rotation direction, the groove portions each comprise: a groove
bottom portion that faces the distal end portion in a center axis
direction; a first inner surface that continues to a rear side of
the groove bottom portion in the rotation direction, and comes into
contact with the first outer surface; and a second inner surface
that continues to a front side of the groove bottom portion in the
rotation direction, and faces the first inner surface, the welding
contacting portion is formed in a corner portion between the distal
end portion and the second outer surface of the corresponding
blade, and the welding contacted portion, as an inclined surface,
is formed on the second inner surface of the groove portion. In
this case, at least a ridgeline of the corner portion of the
welding contacting portion is in parallel with the other end
surface of the impeller main body member.
Advantageous Effects of the Invention
[0008] In the impeller for a fluid pump according to the present
invention, the welding contacting portion of the impeller cover
member and the welding contacted portion of the impeller main body
member are welded to each other with the distal end portions of the
blades of the impeller cover member arranged in parallel with the
other end surface of the impeller main body member, and pressure
and vibrations applied to the impeller cover member and the
impeller main body member with the other end surface side of the
impeller main body member serving as the surface to be in contact
with an ultrasonic horn. Thus, a lower vibration transmission loss
(energy loss in vibration transmission) can be achieved with a
pressing surface of the ultrasonic horn being in parallel with a
welded portion of the blades and the impeller main body member,
whereby stable quality can be achieved with high joining strength.
All things considered, the impeller (closed impeller),
manufacturing of which including welding for joining between the
impeller cover member and the impeller main body member, can
achieve higher joining strength to achieve higher pump performance,
with a simple structure and with no cost increase. The
configuration further has a potential of achieving a complex blade
shape and a large capacity pump.
[0009] In the impeller for a fluid pump according to the present
embodiment, a welded portion between the welding contacting portion
and the welding contacted portion is formed as a share joint. The
first inner surface serves as a guiding surface when the welding
contacting portion is pressed toward the welding contacted portion.
The inclined surface of the welding contacted portion might cause
the welding contacting portion to move in a separating direction
(toward the first inner surface). Still, the first outer surface
and the first inner surface are in contact with each other, so that
the movement of the welding contacting portion in the separating
direction can be restricted. Thus, on the rear side in the rotation
direction of the blades, the first outer surface and the first
inner surface are in a slidable contact state, whereby a higher
positioning accuracy between the welding contacting portion and the
welding contacted portion can be achieved at the time of welding.
Furthermore, on the front side in the rotation direction of the
blades, the welded portion between the welding contacting portion
and the welding contacted portion is formed as a share joint,
ensuring a large welding area. Thus, even higher joining strength
can be achieved between the impeller cover member and the impeller
main body member. Furthermore, with this configuration, air is less
likely to be mixed at the time of welding, whereby defects such as
a void can be prevented.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] FIG. 1 is a front view illustrating a water pump including
an impeller according to the present embodiment.
[0011] FIG. 2 is a cross-sectional view illustrating the water
pump.
[0012] FIG. 3 is a block diagram illustrating a circulation path of
a cooling water that is circulated by the water pump.
[0013] FIG. 4 is a perspective view illustrating an impeller
according to the present embodiment.
[0014] FIG. 5A is a front view illustrating the impeller, and FIG.
5B is a cross-sectional view illustrating the impeller taken along
an arrow A-A.
[0015] FIG. 6A is a front view illustrating a cover of the
impeller, and FIG. 6B is a rear view illustrating the cover.
[0016] FIG. 7A is a cross-sectional view illustrating the cover
taken along an arrow B-B, and FIG. 7B is a cross-sectional view
illustrating a blade of the cover taken along an arrow C-C.
[0017] FIG. 8A is a front view illustrating a shroud of the
impeller, and FIG. 8B is a front view illustrating a long groove of
the shroud.
[0018] FIG. 9A is a cross-sectional view of the shroud, and FIG. 9B
is a cross-sectional view of the long groove taken along an arrow
D-D.
[0019] FIG. 10 is a cross-sectional view illustrating a method
(welding method) of manufacturing the impeller.
[0020] FIG. 11A is a cross sectional view illustrating a state
where a welding contacting portion of a blade is in contact with a
welding contacted portion of a long groove, and FIG. 11B is a
cross-sectional view illustrating a state where a welding
contacting portion of a blade and a welding contacted portion of a
long groove are welded.
DESCRIPTION OF THE EMBODIMENTS
[0021] A preferred embodiment of the present invention is described
below with reference to the drawings. A water pump (fluid pump)
according to one embodiment of the present invention is disposed in
a cooling water circulation path of an engine, and causes forcible
circulation of cooling water. First of all, an overall
configuration of the water pump is described with reference to
FIGS. 1 to 3.
Configuration of Water Pump
[0022] A water pump 1 is assembled based on a pump base 10 disposed
in a cylinder block of an engine EG. The pump base 10 is provided
with an inlet port 11 and discharge ports 12 and 13. The inlet port
11 is connected to a return flow path L2 of the cooling water. The
discharge ports 12 and 13 are connected to a discharge flow path L1
of the cooling water leading to a water jacket WJ. The ports 11,
12, and 13 are each open on a front surface side of the pump base
10.
[0023] The pump base 10 has a back surface side on which a pump
body 20 is detachably attached with a plurality of bolts 21, and
thus a pump chamber 2 is formed as a space defined by the pump base
10 and the pump body 20. An O ring 22 is disposed between surfaces
of the pump base 10 and the pump body 20 facing each other, to
guarantee sealing of the pump chamber 2. The pump base 10 and the
pump body 20 form a pump casing.
[0024] A pump pulley 40 is attached on an outer circumference side
of the pump body 20 via a driving shaft 30. The pump pulley 40 has
an outer circumference surface provided with a belt groove 41 by
which a drive belt DB, connected to a crank shaft CS of the engine
EG, is spanned. The pump pulley 40 is drivingly rotated by
receiving rotational force of the crank shaft CS transmitted
thereto via the drive belt DB spanned around the belt groove
41.
[0025] The driving shaft 30 has a base end portion being
press-fitted to the pump body 20, extends through an opening
portion 23 of the pump body 20 to the pump chamber 2, and has a
rotational axis matching that of the pump pulley 40. The driving
shaft 30 is rotatably supported by the pump body 20 via a bearing
31 being fitted to the pump body 20. The driving shaft 30 has a
distal end portion to which an impeller 100, disposed in the pump
chamber 2, is coaxially attached. The pump pulley 40, the driving
shaft 30, and the impeller 100 can integrally and coaxially rotate.
A mechanical seal 24 seals between the opening portion 23 of the
pump body 20 and the driving shaft 30, to achieve the sealing of
the pump chamber 2.
[0026] As illustrated in FIG. 3, the pump pulley 40 of the water
pump 1 is drivingly rotated by the crank shaft CS of the engine EG,
via the drive belt DB. Thus, the driving shaft 30, integrally
coupled with the pump pulley 40, rotates together with the impeller
100. The rotation of the impeller 100 causes the cooling water in
the return flow path L2 to be sucked into the inlet port 11 and
then receive centrifugal force in the pump chamber 2 to be
discharged to the discharge flow path L1 through the discharge
ports 12 and 13. The cooling water discharged to the discharge flow
path L1 is pumped to the water jacket WJ to cool a cylinder and the
like of the engine EG, flows to a radiator RD through a connection
flow path CL to be radiated, and then returns to the water pump 1
through the return flow path L2 and thus circulates in this manner.
The connection flow path CL is provided with a switching valve SV
that operates in accordance with a thermostat in such a manner that
the cooling water with temperature higher than a predetermined set
temperature flows to the radiator RD and the cooling water with
temperature lower than the predetermined set temperature flows to a
bypath flow path BL. The bypass flow path BL is connected to the
return flow path L2, and thus allows the cooling water flowing
therein to be directly sucked into the water pump 1 without flowing
in the radiator RD. In this manner, the water pump 1 causes the
cooling water to forcibly circulate in the water jacket WJ.
Configuration of Impeller
[0027] The impeller 100 according to the present embodiment is
described by further referring to FIG. 4, FIGS. 5A and 5B, FIGS. 6A
and 6B, FIGS. 7A and 7B, FIGS. 8A and 8B and FIGS. 9 and 9B. An
upper side and a lower side in an axial direction (center axis
direction) are hereinafter also referred to as a "one end side" and
a "the other end side", based on an orientation of the impeller 100
arranged as illustrated in FIG. 5B, for the sake of description. In
FIG. 4, FIGS. 5A and 5B, FIGS. 6A and 6B, FIGS. 7A and 7B, FIGS. 8A
and 8B and FIGS. 9 and 9B, a hatching of a cross-sectional portion
is omitted for the sake of illustration. In each figure, a rotation
direction of the impeller 100 is indicated by an arrow
[0028] As illustrated in FIG. 4 and FIGS. 5A and 5B, the impeller
100 is what is known as a closed impeller mainly including: a cover
110 on which a plurality of blades 130 are integrally formed; and a
shroud 150 joined to the cover 110. The impeller 100 rotates in
synchronization with the driving shaft 30 described above, to suck
the cooling water through an inlet port 123 formed on the cover 110
and to discharge the cooling water through a discharge port 139 as
a space between blades 130.
[0029] As illustrated in FIGS. 6A and 6B and FIGS. 7A and 7B, the
cover 110 is an integrally molded member made of resin (preferably
made of PPS resin), and has a configuration in which the plurality
of blades 130 are integrally provided on a cover main body 120.
[0030] The cover main body 120 has a truncated cone shape
(substantially umbrella shape) with a diameter increasing from the
one end side to the other end side. The inlet port 123 having a
circular hole shape, through which the cooling water from the inlet
port 11 is introduced, is formed through the center of the cover
main body 120 in the axial direction. The cover main body 120 has a
front surface 121 facing an inner surface of the pump base 10, and
has a back surface 122 provided with the plurality of blades (seven
blades in the present embodiment) 130 arranged at an equal interval
along a circumference direction. The cover main body 120 has a
tapered shape (substantially umbrella shape), so that the cooling
water can smoothly flow along the back surface 122 of the cover
main body 120.
[0031] A circumference edge portion 124 of the inlet port 123 in
the cover main body 120 is formed to be shorter in the axial
direction compared with a conventional configuration as illustrated
in FIG. 2. The circumference edge portion 124 has an end surface
(left surface in FIG. 2) facing an end surface of a pipe 14 of the
inlet port 11 (right surface in FIG. 2) with a slight gap in
between. Thus, the closed impeller can be formed with the impeller
100 accommodated in the pump chamber 2 while protruding in the
axial direction (left direction in FIG. 2), by a length
corresponding to the thickness of the cover main body 120, without
increasing the volume of the pump chamber 2, even when an existing
pump casing is used. Furthermore, a reverse flow of the cooling
water through the gap between the cover main body 120 and the pump
base 10 can be reduced.
[0032] Each of the blades 130 is formed to have a plate shape
curved along a center line including a line curved on one side and
a line curved on the opposite side that are continuously connected
to each other. The plurality of blades 130 are radially arranged
about the axis, with a distance between adjacent blades 130 in the
circumference direction gradually increasing from the inner side in
a radial direction toward the outer side in the radial direction
(that is, in a discharge direction). The blades 130 are each
inclined to have a height reducing from the inner side toward the
outer side in the radial direction, to conform with the tapered
shape of the cover main body 120. Thus, adjacent ones of the blades
130 each have the cross-sectional area set to be substantially the
same between an opening on the inner side in the radial direction
(suction side) and an opening on the outer side in the radial
direction (discharge side), whereby a uniform inner flowrate can be
achieved.
[0033] The blades 130 each include: a distal end portion 131 facing
the shroud 150; a rear side outer surface 132 formed on a rear side
in the rotation direction; and a front side outer surface 133
formed on a front side in the rotation direction. The rear side
outer surface 132 and the front side outer surface 133 are formed
as inclined surfaces and each extend from the one end side toward
the other end side in the axial direction while being inclined
toward the counterpart by about 2.degree.. Thus, the blade 130 has
a shape slightly tapered from the one end side toward the other end
side, in a cross-sectional view. The blades 130 are each formed in
such a manner that a side on the distal end portion 131 can be
received in a corresponding one of long grooves 170 formed on the
shroud 150. A corner portion between the distal end portion 131 and
the front side outer surface 133 of the blade 130 is formed as a
portion (welding contacting portion 135) to be welded with the
shroud 150.
[0034] As illustrated in FIGS. 8A and 8B and FIGS. 9 and 9B, the
shroud 150 includes: a shroud main body 160 formed as an integrally
molded member made of resin (preferably, made of PPS resin); and a
bush 180 made of metal that is inserted molded in the shroud main
body 160.
[0035] The shroud main body 160 includes: a boss portion 161 having
a cylindrical shape; and a disk portion 165 formed to have
substantially the same diameter as the cover 110. The bush 180,
having a hollow shape, is buried in the center of the boss portion
161, and is connected to the driving shaft 30 in an integrally
rotatable manner. The disk portion 165 has a side of a front
surface 166 on which the plurality of blades 130 are welded and
thus joined, and has a side of a back surface 167 serving as a
surface to be in contact with an ultrasonic horn H at the time of
welding (see FIG. 10). Circular balance holes 168 are formed
through the front and the back surfaces at three portions of the
disk portion 165.
[0036] The long grooves 170 are formed at positions matching those
of the blades 130, and radially extend from a portion close to the
outer circumference surface of the boss portion 161, on the front
surface 166 of the disk portion 165. The long grooves 170 each have
one end side facing the cover 110 open, and thus can receive the
side of the distal end portion 131 of the blade 130.
[0037] The long grooves 170 each include: a groove bottom portion
171; a rear side inner surface 172 formed on the rear side in the
rotation direction; and a front side inner surface 173 formed on
the front side in the rotation direction.
[0038] The rear side inner surface 172 is formed as an inclined
surface extends from the other end side toward the one end side in
the axial direction, while being inclined by about 2.degree. toward
a side opposite to the front side inner surface 173.
[0039] The front side inner surface 173 includes a first front side
inner surface 174, a second front side inner surface 175, and a
third front side inner surface 176 that are arranged in this order
from a bottom surface side. The first front side inner surface 174
and the rear side inner surface 172 face each other while being
separated from each other by a first groove width. The first front
side inner surface 174 is formed as an inclined surface that
extends from the other end side to the one end side in the axial
direction, while being inclined by about 2.degree. toward the side
opposite to the rear side inner surface 172. The third front side
inner surface 176 and the rear side inner surface 172 face each
other while being separated from each other by a second groove
width that is larger than the first groove width. The second front
side inner surface 175 connects between the first front side inner
surface 174 and the third front side inner surface 176 and is
formed as an inclined surface that extends from the other end side
to the one end side in the axial direction, while being inclined by
about 45.degree. toward the side opposite to the rear side inner
surface 172. The rear side inner surface 172 serves as a portion
that may be in contact with the rear side outer surface 132 of the
blade 130. The second front side inner surface 175 serves as a
portion (welding contacted portion 177) to be welded with the
welding contacting portion 135 of the blade 130.
[0040] The excess amount of molten resin produced when the welding
contacting portion 135 and the welding contacted portion 177 are
welded is stored in a portion, in the long groove 170, close to the
groove bottom portion 171 and the third front side inner surface
176. More specifically, a gap between the groove bottom portion 171
of the long groove 170 and the distal end portion 131 of the blade
130, a gap between the third front side inner surface 176 of the
long groove 170 and the front side outer surface 133 of the blade
130, and the like function as a resin reservoir for the
welding.
[0041] In the present embodiment, the distal end portion 131 of the
blade 130 and the long groove 170 of the shroud 150 are welded to
each other only on the front side in the rotation direction.
Alternatively, a method of welding the distal end portion 131 of
the blade 130 and the long groove 170 of the shroud 150 to each
other on both front and rear sides in the rotation direction may be
employed. However, this method involves a risk of producing large
residual stress due to the difference in the melting timing between
the front and rear sides in the rotation direction. Thus, the
welding is preferably performed only on one side (the front side or
the rear side) in the rotation direction.
Method of Manufacturing Impeller
[0042] Next, a method of manufacturing the impeller 100 according
to the present embodiment will be described by further referring to
FIG. 10 and FIGS. 11A and 11B. In FIGS. 11A and 11B, the welding
contacting portion 135 and the welding contacted portion 177 are
illustrated in an upside-down positional relationship to facilitate
the understanding of the welding process.
[0043] In the present embodiment, the impeller 100 is manufactured
by joining the cover 110 and the shroud 150, both made of resin, by
ultrasonic welding.
[0044] To manufacture the impeller 100 in this manner, first of
all, the cover 110 and the shroud 150 are separately molded. The
cover 110 is made of synthetic resin and through injection molding
using a predetermined mold. Similarly, the shroud 150 is made of
synthetic resin and through injection molding using a predetermined
mold. In the shroud 150, the bush 180, as a metallic insert member,
is formed by insert molding.
[0045] Next, the cover 110 and the shroud 150 are mounted to a jig
900. The jig 900 has a substantially cylindrical shape and has an
opening portion 901, on an upper side, in which the cover 110 and
the shroud 150 can be mounted. The cover 110 and the shroud 150 are
mounted in the opening portion 901 of the jig 900 in this order and
thus are respectively on a lower side and an upper side. In this
process, the cover 110 and the shroud 150 are positioned in the
circumference direction, so as to be vertically stacked in the
opening portion 901 of the jig 900, with the distal end portions
131 of the blades 130 received in the long grooves 170 of the
shroud 150. A guide pin 910, having a shaft shape, vertically
stands at the center of the jig 900. The guide pin 910 is inserted
through the bush 180 of the shroud 150, and thus the shroud 150 is
coaxially arranged with the jig 900. The outermost circumference
surfaces of the cover 110 and the shroud 150 and an inner
circumference surface of the jig 900 form what is known as a spigot
joint structure with which alignment adjustment of the cover 100
and the shroud 150 can be performed. The jig 900 is in surface
contact with the side of the front surface 121 (lower side in FIG.
10) of the cover 110. Thus, when the cover 110 and the shroud 150
are mounted to the jig 900, the axis of the cover 110 and the axis
of the shroud 150, both extending in the vertical direction,
substantially match.
[0046] Next, the ultrasonic horn H of a welding machine is brought
into contact with the back surface 167 of the shroud 150, and
applies ultrasonic vibrations and pressing force to the cover 110
and the shroud 150 vertically stacked, whereby the ultrasonic
welding of the cover 110 and the shroud 150 is achieved. More
specifically, the pressing force and the ultrasonic vibrations are
applied downward, in a state where the sides of the distal end
portions 131 of the blades 130 are received in the long grooves 170
of the shroud 150 and the welding contacting portions (corner
portions) 135 of the blades 130 are in contact with the welding
contacted portions (inclined surfaces) 177 of the long grooves
170.
[0047] When the shroud 150 is pressed downward by the ultrasonic
horn H, the rear side outer surfaces 132 of the blades 130 come
into contact with (and slide on) the rear side inner surfaces 172
of the long grooves 170. Thus, the rear side inner surfaces 172 and
the rear side outer surfaces 132 serve as guiding surfaces when the
welding contacting portion 135 is pressed toward the welding
contacted portion 177. When the welding contacting portion 135 is
pressed toward the welding contacted portion 177, an effect of the
inclined surface of the welding contacted portion 177 on the
welding contacting portion 135 might cause the blade 130 to
entirely move toward the rear side inner surface 172 in the long
groove 170. Still, the rear side outer surface 132 and the rear
side inner surface 172 are in contact with each other, so that the
welding contacting portion 135 and the welding contacted portion
177 can stay in contact with each other at an appropriate position.
The ultrasonic vibrations produced by the ultrasonic horn H
propagate to be concentrated at a contact portion between the
welding contacting portion (corner portion) 135 of the blade 130
and the welding contacted portion (inclined surface) 177 of the
long groove 170. Thus, frictional heat is generated at the contact
portion between the members. Thus, the contact portion melts,
whereby the cover 110 and the shroud 150 are welded to each
other.
[0048] In this manner, a share joint is formed between the welding
contacting portion 135 and the welding contacted portion 177, so
that a wide welding area can be ensured therebetween, whereby
higher joining strength (mechanical strength) can be achieved
between the cover 110 and the shroud 150. In the share joint, only
the actually melted surfaces of the welding contacting portion 135
and the welding contacted portion 177 are in contact with each
other, whereby air is less likely to be mixed at the time of
welding. Thus, defects such as a void can be prevented.
Furthermore, the joining is achieved with the rear side outer
surface 132 and the rear side inner surface 172 in contact with
each other. Thus, the rear side inner surface 172 functions as a
wall receiving a load acting on the blade 130 while the water pump
1 is in operation.
[0049] As described above, in the impeller 100 according to the
present embodiment, the welding contacting portion 135 of the cover
110 and the welding contacted portion 177 of the shroud 150 are
welded to each other with the distal end portion 131 of the blade
130 (more specifically, a ridgeline of the corner portion of the
welding contacting portion 135) arranged in parallel with the back
surface of the shroud 150, and pressure and vibrations applied to
the cover 110 and the shroud 150 with the back surface side of the
shroud 150 serving as the surface to be in contact with the
ultrasonic horn H. Thus, a lower vibration transmission loss
(energy loss in the vibration transmission) can be achieved with
the pressing surface of the ultrasonic horn H being in parallel
with the welded portion of the blade 130 and the shroud 150,
whereby stable quality can be achieved with high joining strength.
All things considered, the impeller (closed impeller) 100,
manufacturing of which including welding for joining between the
cover 110 and the shroud 150, can achieve higher joining strength
to achieve higher pump performance, with a simple structure and
with no cost increase. The configuration further has a potential of
achieving a complex blade shape and a large capacity pump.
[0050] In the impeller 100 according to the present embodiment, the
welded portion between the welding contacting portion 135 and the
welding contacted portion 177 is formed as a share joint. The rear
side inner surface 172 serves as a guiding surface when the welding
contacting portion 135 is pressed toward the welding contacted
portion 177. The inclined surface of the welding contacted portion
177 might cause the welding contacting portion 135 to move in a
separating direction (toward the rear side inner surface 172).
Still, the rear side outer surface 132 and the rear side inner
surface 172 are in contact with each other, so that the movement of
the welding contacting portion 135 in the separating direction can
be restricted. Thus, on the rear side in the rotation direction of
the blade 130, the rear side outer surface 132 and the rear side
inner surface 172 are in a slidable contact state, whereby a higher
positioning accuracy between the welding contacting portion 135 and
the welding contacted portion 177 can be achieved at the time of
welding. Furthermore, on the front side in the rotation direction
of the blade 130, the welded portion between the welding contacting
portion 135 and the welding contacted portion 177 is formed as a
share joint, ensuring a large welding area. Thus, even higher
joining strength can be achieved between the cover 110 and the
shroud 150. Furthermore, with this configuration, air is less
likely to be mixed at the time of welding, whereby the defects such
as a void can be prevented.
[0051] The present invention is not limited to the embodiment
described above and can be refined in various ways without
departing from the gist of the present invention.
[0052] The embodiment is described above with a share joint as an
example. However, the configuration should not be construed in a
limiting sense. The embodiment may be applied to an energy direct
(ED) joint for example. An example of the ED joint has the
following configuration. Specifically, a welding contacting
portion, as a triangular protrusion (corner portion) formed on the
distal end portion of the blade, and a welding contacted portion,
as a flat surface formed in a groove, may be welded to each other.
Alternatively, the welding contacting potion as the flat surface
formed on the distal end portion of the blade and the welding
contacted portion as the triangular protrusion (corner portion) in
the groove may be welded to each other.
[0053] The embodiment is described above with a water pump driving
by an engine as an example. However, this configuration should not
be construed in a limiting sense, and the embodiment may be applied
to an electric water pump. Furthermore, the present invention is
not limited to the water pump, and may be applied to other types of
fluid pumps such as a fuel pump and an oil pump.
EXPLANATION OF NUMERALS AND CHARACTERS
[0054] 1 water pump (fluid pump)
[0055] 2 pump chamber
[0056] 10 pump base
[0057] 20 pump body
[0058] 100 impeller
[0059] 110 cover (impeller cover member)
[0060] 120 cover main body
[0061] 130 blade
[0062] 131 distal end portion
[0063] 132 rear side outer surface (first outer surface)
[0064] 133 front side outer surface (second outer surface)
[0065] 135 welding contacting portion
[0066] 150 shroud (impeller main body member)
[0067] 170 long groove (groove portion)
[0068] 172 rear side inner surface (first inner surface)
[0069] 173 front side inner surface (second inner surface)
[0070] 177 welding contacted portion
[0071] 180 bush
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