U.S. patent application number 11/730956 was filed with the patent office on 2007-10-11 for pump and manufacturing method thereof.
This patent application is currently assigned to Matsushita Electric Works, Ltd.. Invention is credited to Takuya Akiyoshi.
Application Number | 20070237660 11/730956 |
Document ID | / |
Family ID | 38575494 |
Filed Date | 2007-10-11 |
United States Patent
Application |
20070237660 |
Kind Code |
A1 |
Akiyoshi; Takuya |
October 11, 2007 |
Pump and manufacturing method thereof
Abstract
A pump includes a pump unit having an impeller for sucking
and/or discharging liquid; a motor unit for driving the pump unit;
a case for accommodating the pump unit; a partition plate for
isolating the motor unit from the pump unit; and a mold resin
integrally formed with the motor unit to protect the motor unit.
Further, a bottom portion of a cylindrical portion projecting from
the partition plate to the motor unit has a liquid-free surface
having a convex spherical shape. Moreover, a method of
manufacturing a pump, the method includes the steps of installing a
partition plate at a lower half; installing a stator and a
controlling part at the partition plate; closing the lower half
with an upper half; curing resin after filling the resin into a
cavity formed between the lower and the upper half; opening a mold;
and extracting a molded motor product.
Inventors: |
Akiyoshi; Takuya; (Fukuoka,
JP) |
Correspondence
Address: |
BACON & THOMAS, PLLC
625 SLATERS LANE, FOURTH FLOOR
ALEXANDRIA
VA
22314
US
|
Assignee: |
Matsushita Electric Works,
Ltd.
Osaka
JP
|
Family ID: |
38575494 |
Appl. No.: |
11/730956 |
Filed: |
April 5, 2007 |
Current U.S.
Class: |
417/423.11 ;
310/86; 310/87; 417/423.3 |
Current CPC
Class: |
F04D 13/0626 20130101;
F04D 29/628 20130101 |
Class at
Publication: |
417/423.11 ;
417/423.3; 310/86; 310/87 |
International
Class: |
F04B 17/00 20060101
F04B017/00 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 7, 2006 |
JP |
2006-106481 |
Claims
1. A pump comprising: a pump unit having an impeller for sucking
and/or discharging liquid; a motor unit for driving the pump unit;
a case for accommodating the pump unit; a partition plate for
isolating the motor unit from the pump unit; and a mold resin
integrally formed with the motor unit to protect the motor unit,
wherein a bottom portion of a cylindrical portion projecting from
the partition plate to the motor unit has a liquid-free surface
having a convex spherical shape.
2. The pump of claim 1, wherein a liquid contact surface of the
bottom portion of the cylindrical portion has a concave spherical
shape.
3. A method of manufacturing a pump, the method comprising the
steps of: installing a partition plate at a lower half; installing
a stator and a controlling part at the partition plate; closing the
lower half with an upper half; curing resin after filling the resin
into a cavity formed between the lower and the upper half; opening
a mold; and extracting a molded motor product.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to a pump driven by a motor
for sucking and discharging liquid, and a manufacturing method
thereof.
BACKGROUND OF THE INVENTION
[0002] In general, a pump includes a motor unit having a stator for
generating a magnetic field and a controller for controlling the
stator, a pump unit having an impeller driven by the magnetic field
generated from the stator and sucking/discharging liquid such as
liquid etc., and a partition plate for isolating the motor unit
from the pump unit.
[0003] Particularly, in order to prevent corrosion of the motor
unit due to intrusion of liquid leaked from the pump unit or high
humidity in pump installation environment, resin is applied to the
motor unit for protection.
[0004] In the above described pump, since the partition plate can
be deformed toward the outside of the pump due to a pressure
generated during operation of the pump, a bottom surface of the
partition plate should have a large thickness. In addition, use of
a large amount of resin may cause increase in manufacturing cost of
the pump (see, for example, Japanese Patent Laid-open Publication
No. 2004-60620).
[0005] Further, when resin is injected into an injection mold in
order to cover the motor unit with the resin and cure the resin,
the bottom surface of the partition plate is pressed and deformed
by a resin pressure. It is, therefore, difficult to obtain an inner
dimension of the pump unit within a desired tolerance limit. For
this reason, parts related to position precision, for example, an
impeller, etc. disposed in the pump should be machined by a lathe
and so on, thereby increasing the manufacturing cost of the
pump.
SUMMARY OF THE INVENTION
[0006] It is, therefore, an object of the present invention to
provide a pump capable of reducing a material used for a partition
plate, and suppressing deformation of a bottom surface of the
partition plate to increase a dimension stability of product.
[0007] In accordance with an embodiment of the present invention,
there is provided a pump including a pump unit having an impeller
for sucking/discharging liquid, a motor unit for driving the pump
unit, a case for accommodating the pump unit, a partition plate for
isolating the motor unit from the pump unit, and a mold resin
integrally formed with the motor unit to protect the motor unit,
wherein a bottom portion of a cylindrical portion projecting from
the partition plate to the motor unit has a liquid-free surface
having a convex spherical shape surface.
[0008] Here, the bottom portion of the cylindrical portion has a
relatively small area of plate and a high strength.
[0009] As a result, it is possible to reduce a material used for
the partition plate. In addition, it is possible to provide the
pump capable of suppressing deformation of the bottom surface of
the partition plate to increase dimension stability of
products.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] The above and other objects and features of the present
invention will become apparent from the following description of an
embodiment given in conjunction with the accompanying drawings, in
which:
[0011] FIG. 1 is a cross-sectional view of a pump in accordance
with a first embodiment of the present invention;
[0012] FIG. 2 is a cross-sectional view showing a process of
installing parts at a lower half in accordance with the embodiment
of the present invention;
[0013] FIG. 3 is a cross-sectional view showing a process of
closing a mold before forming a molding process in accordance with
the embodiment of the present invention;
[0014] FIG. 4 is a cross-sectional view showing a process of
filling resin into a mold in accordance with the embodiment of the
present invention; and
[0015] FIG. 5 is a cross-sectional view showing a process of
extracting a motor product after the molding process in accordance
with the embodiment of the present invention.
DETAILED DESCRIPTION OF THE EMBODIMENT
[0016] Hereinafter, an embodiment of the present invention will be
described in detail with reference to the accompanying drawings so
that they can be readily implemented by those skilled in the
art.
Embodiment 1
[0017] As shown in FIG. 1, a mold resin 2 formed of heat curable
plastic, etc. is installed at a left side of a pump unit 4 to cover
a motor unit 1 for driving the pump unit 4. A case 3 formed of
plastic such as PPS (polyphenylene sulfide) or a metal such as a
stainless steel is disposed at a right side of the pump unit 4.
[0018] A partition plate 5 formed of plastic such as PPS or a metal
such as a stainless steel is similarly installed between the motor
unit 1 and the case 3 isolating the motor unit 1 from the pump unit
4 to prevent intrusion of circulation liquid into the motor unit 1
from the pump unit 4. In addition, the partition plate 5 projects
at its center adjacent to the motor unit 1 in a cylindrical shape.
That is, the partition plate 5 has a cylindrical portion 5A having
a size sufficient to accommodate the pump unit 4 therein. A flange
in contact with the case 3 and the motor unit 1 is formed around an
opening of the cylindrical portion 5A.
[0019] The motor unit 1 includes a magnetic field generating stator
6 having a hollow cylindrical shape, a controller 6 for controlling
the stator 6, and a mold resin 2 cured to cover the stator 6 and
the controller 7. The stator 6 is disposed on a periphery of the
cylindrical portion 5A of the partition plate 5, and the outside of
the stator 6 is covered with the resin.
[0020] A support plate 8 is connected to a left side of the stator
6, and a controller 7 having electronic parts 16A and 16B, such as
resistors, transistors, and the like, is attached to the support
plate 8.
[0021] Meanwhile, the pump unit 4 includes a cylindrical rotor 11
formed of a permanent magnet and rotated by the magnetic field
generated from the stator 6; a cylindrical impeller 13 integrally
formed with the rotor 11 and formed of plastic such as PPS to
suck/discharge circulation liquid by using a plurality of blades 12
attached to its surface; a cylindrical shaft 14 formed of a metal
such as stainless steel and rotatably supporting the rotor 11 and
the impeller 13; and hollow cylindrical reception plates 15 formed
of ceramic for fixing the shaft 14.
[0022] The rotor 11 is disposed while facing the stator 6 with the
partition plate 5 interposed therebetween in the cylindrical
portion 5A protruded toward the motor unit 1.
[0023] The impeller 13 having the plurality of blades 12 formed at
its outer surface is disposed at a right side of the rotor 11 and
integrally formed therewith, and the shaft 14 for rotatably
supporting the rotor 11 and the impeller 13 is installed at the
center of the rotor 11 and the impeller 13.
[0024] In addition, the reception plates 15 are attached to both
ends of the shaft 14 to fix the shaft 14.
[0025] When the pump as described above is driven, a pressure in
the pump unit 4 is increased. Therefore, the increased inner
pressure may be applied to a liquid contact surface 5a inside the
bottom portion 5B of the cylindrical portion 5A of the partition
plate 5, thereby causing deformation of the partition plate 5
toward the mold resin 2. However, since a liquid-free convex
surface 5b of the bottom portion 5B at the cylindrical portion 5A
of the partition plate 5 has a spherical shape, for example, a
radius of about 300 mm, the convex surface 5b has a second moment
of area larger than that of a conventional flat surface having a
uniform thickness to increase its strength, though the convex
surface has a relatively small cross-section, thereby suppressing
deformation of the bottom surface of the partition plate. As a
result, it is possible to reduce an amount of material used for the
partition plate 5, thus reducing the manufacturing cost
thereof.
[0026] In addition, when the liquid contact surface 5a of the
bottom surface of the partition plate is flat, the bottom portion
has a variable thickness, for example, an outer periphery of about
2 mm and a center of about 3 mm. Therefore, a second moment of area
of the variable thickness becomes about 2.5 times larger than that
of the uniform thickness of 2 mm, thereby increasing the strength.
Alternatively, when the liquid contact surface 5a of the bottom
surface of the partition plate is concave, whereas the bottom
portion has a uniform thickness, e.g., a hollow spherical shape of
about 2 mm thickness, a second moment of area of the concave shape
becomes approximately 1.25 times larger than that of the uniform
thickness of 2 mm, thereby increasing the strength.
[0027] Here, a process of covering the motor unit 1 with mold resin
will be described.
[0028] As shown in FIG. 2, reference numeral 9 designates a lower
half of a forming mold. The lower half 9 has a cylindrical convex
portion 20 corresponding to the cylindrical portion 5A of the
partition plate 5. First, the partition plate 5 is installed at the
lower half 9, and then, the stator 6 and the controller 7 are
installed at the cylindrical portion 5A projected from the
partition plate 5. At this time, the controller 7 has already been
attached to the support plate 8 provided at the stator 6.
[0029] In FIG. 2, reference numeral 10 designates an upper half of
the forming mold. When the forming apparatus is initiated, as shown
in FIG. 3, the lower half 9, the stator 6 and the controller 7 are
raised toward the upper half 10, and the mold gets closed
thereafter. When the mold is closed, a cavity 21 is formed in the
mold. Then, resin is introduced from a resin inlet port 17 formed
at the upper half 10, and a pressure is continuously applied to the
resin from the forming apparatus, thereby spreading the mold resin
2 to all the corners in the mold cavity 21. In FIG. 4, the mold
resin 2 is shown as being dispersed to all the corners in the
cavity 11.
[0030] Here, a pressure is applied to the liquid-free surface 5b of
the bottom surface of the partition plate from the forming
apparatus via the resin. A gap S of about 0.2 mm may be generated
between the liquid contact surface 5a of the bottom surface of the
partition plate 5 and a ceiling surface 20a of the convex portion
20 of the lower half 9 due to a dimension difference of the
partition plate 5. When the strength of the bottom surface of the
partition plate (the bottom portion 5B of the cylindrical upper
part 5A) is insufficient, the bottom surface may be deformed by the
resin pressure applied to the liquid-free surface 5B of the bottom
surface of the partition plate 5 until the liquid contact surface
5a of the bottom surface of the partition plate facing the
liquid-free surface makes contact with a surface of the upper
surface 12a of the lower half 9.
[0031] As a result, a position of the reception plate installation
surface 18 may be deformed toward the lower half 9 such that the
position dimension of the reception plate installation surface 18
may be undesirably different from the original layout (design) when
the components are completed. However, since the liquid-free
surface 5b has a convex spherical shape while the surface can
resist the resin pressure based on the theory that surface
particles push each other to a pressure applied to the mold resin 2
by the forming apparatus, it is possible to suppress deformation of
the bottom surface of the partition plate 5 to increase dimension
stability of products.
[0032] In the following processes, after keeping the mold closed
until the mold resin 2 is cured, the mold is opened and the molded
motor product is extracted. FIG. 5 illustrates the molded motor
product extracted from the mold. Reference numeral 19 designates a
spool, which may be detached using a tool such as a nipper to
complete the molded motor product.
[0033] While a liquid supply apparatus adapting a pump in
accordance with a first embodiment of the present invention has
been described as a bath liquid circulation apparatus, the pump in
accordance with the present invention may be adapted to various
other liquid supply apparatuses such as a well pump apparatus, a
hot liquid supply apparatus, a drain liquid supply apparatus, and
so on.
[0034] The pump unit in accordance with the present invention may
be adapted to various pumps used for a fuel cell device, a heat
pump apparatus, and so on.
[0035] While the invention has been shown and described with
respect to the embodiments, it will be understood by those skilled
in the art that various changes and modifications may be made
without departing from the spirit and scope of the invention as
defined in the following claims.
* * * * *