U.S. patent application number 11/558438 was filed with the patent office on 2008-05-15 for pump.
This patent application is currently assigned to Nidec Shibaura Corporation. Invention is credited to Takenori Kawashima, Masashi Nishimura, Motoi Sawasaki.
Application Number | 20080112824 11/558438 |
Document ID | / |
Family ID | 39369382 |
Filed Date | 2008-05-15 |
United States Patent
Application |
20080112824 |
Kind Code |
A1 |
Sawasaki; Motoi ; et
al. |
May 15, 2008 |
Pump
Abstract
In a pump having a rotor inside a pump chamber which is formed
inside a case which is formed of a resin material, and a resin mold
compound in which an armature is molded with resin, a metallic
cover is provided on a portion of an outer surface of the case
inside the pump, wherein the portion has inferior durability
compared with the rest of the outer surface.
Inventors: |
Sawasaki; Motoi; (Obama-shi,
JP) ; Kawashima; Takenori; (Obama-shi, JP) ;
Nishimura; Masashi; (Obama-shi, JP) |
Correspondence
Address: |
NIDEC CORPORATION;c/o KEATING & BENNETT, LLP
8180 GREENSBORO DRIVE, SUITE 850
MCLEAN
VA
22102
US
|
Assignee: |
Nidec Shibaura Corporation
Obama-shi
JP
|
Family ID: |
39369382 |
Appl. No.: |
11/558438 |
Filed: |
November 9, 2006 |
Current U.S.
Class: |
417/423.7 ;
417/410.1; 417/423.14; 417/423.3 |
Current CPC
Class: |
F05D 2300/43 20130101;
F05D 2300/615 20130101; F04D 29/426 20130101; F04D 29/026 20130101;
F05D 2300/222 20130101 |
Class at
Publication: |
417/423.7 ;
417/410.1; 417/423.3; 417/423.14 |
International
Class: |
F04D 29/40 20060101
F04D029/40 |
Claims
1. A pump, comprising: a pump chamber formed, for forming therein a
pathway for fluid, inside a case formed of a resin material; at
least one intake portion connected to the pump chamber for intaking
therein the fluid; at least one discharge portion connected to the
pump chamber for discharging therefrom the fluid; a rotor located
inside the pump chamber and having therein a rotor magnet, wherein
the rotor rotates along a predetermined rotary shaft; an impeller
rotating along with the rotor so as to direct the fluid to a
predetermined direction; a stator located opposing to the rotor
magnet while having a gap therebetween and located outside of the
pump chamber, wherein the stator includes therein an armature which
is a generator of a magnetic field; and a metallic cover affixed,
for increasing durability of the case, to a portion of the case to
which an internal pressure generated by the fluid inside the pump
chamber is applied.
2. The pump according to claim 1, wherein the metallic cover covers
over a weld line generated on a surface of the case, and is affixed
to the case on one side and the other side of the weld line.
3. The pump according to claim 1, wherein the internal pressure of
the fluid inside the pump chamber is greater than approximately 250
KPa.
4. The pump according to claim 1, wherein the metallic cover is
affixed to the case by a screw at a portion of the case radially
outside of the pump chamber.
5. The pump according to claim 1, wherein: the case includes an
upper case and a lower case in an axial direction; the lower case
is cup shaped for containing therein the rotor; and the metallic
cover is affixed to a top surface in an axial direction of the
upper case.
6. The pump according to claim 1, wherein: the metallic cover is
located on top side and bottom side in an axial direction of the
case; and the case is, due to the metallic cover provided thereto,
constrictedly secured in the axial direction.
7. The pump according to claim 1, wherein: the stator includes
therein a resin mold compound having formed therein an armature
molded with the resin material; and the resin mold compound is
located for making contact with an outer surface of the case.
8. The pump according to claim 5, wherein: the stator includes
therein a resin mold compound having formed therein an armature
molded with the resin material; and the resin mold compound is
located for making contact with at least an outer circumferential
surface of the cup shape of the lower case.
9. The pump according to claim 7, wherein a
resin-mold-compound-side metallic cover is affixed to an outer
surface of the resin mold compound so as to cover over the outer
surface of the resin mold compound.
10. The pump according to claim 9, wherein the case and the resin
mold compound are, due to the metallic cover and the resin mold
compound side cover respectively provided thereto, constrictedly
secured in the axial direction.
11. The pump according to claim 8, wherein a
resin-mold-compound-side metallic cover is affixed to the outer
surface of the resin mold compound so as to cover over the outer
surface of the resin mold compound.
12. The pump according to claim 11, wherein the case and the resin
mold compound are, due to the metallic cover and the resin mold
compound side cover respectively provided thereto, constrictedly
secured in the axial direction.
13. The pump according to claim 10, wherein the metallic cover and
the resin mold compound side metallic cover each are affixed to a
pump base to which a corresponding pump is attached.
14. The pump according to claim 9, wherein a shape of the metallic
cover and that of the resin mold compound side metallic cover are
substantially identical.
15. The pump according to claim 14, wherein: the metallic cover has
formed thereon an opening at an area thereof corresponding to the
intake portion; and provided is a rib for preventing an exposure,
to an outside of the pump, of the resin mold compound at an area of
the opening, and for increasing durability of the resin mold
compound.
16. A pump, comprising: a pump chamber formed inside a case, formed
of a resin material, for forming a pathway for fluid; at least one
intake portion connected to the pump chamber for intaking therein
the fluid; at least one discharge portion connected to the pump
chamber for discharging therefrom the fluid; a rotor located inside
the pump chamber and having therein a rotor magnet, the rotor
rotating along a predetermined rotary shaft; an impeller rotating
along with the rotor so as to direct the fluid to a predetermined
direction; and a stator located opposing to the rotor magnet, while
having a gap therebetween, outside of the pump chamber, wherein the
stator includes therein an armature which is a generator of a
magnetic field, wherein: the stator includes therein a resin mold
compound having formed therein an armature molded with the resin
material; the resin mold compound and the case make contact with
each other and are affixed to each other; and a metallic cover, for
increasing durability of the resin mold compound, is affixed to a
portion of the resin mold compound.
17. A pump, comprising: a pump chamber formed inside a case, formed
of a resin material, for forming a pathway for fluid; at least one
intake portion connected to the pump chamber for intaking therein
the fluid; at least one discharge portion connected to the pump
chamber for discharging therefrom the fluid; a rotor located inside
the pump chamber and having therein a rotor magnet, wherein the
rotor rotates along a predetermined rotary shaft; an impeller
rotating along with the rotor so as to direct the fluid to a
predetermined direction; a stator located opposing to the rotor
magnet, while having a gap therebetween, outside of the pump
chamber; the stator including therein a resin mold compound molding
therein an armature which is a generator of a magnetic field; the
resin mold compound located such that a portion thereof makes
contact with an outer surface of the case; and a reinforcement
board embedded in the portion of the resin mold compound making
contact with the case.
18. The pump according to claim 14, wherein: the case includes an
upper case and a lower case in an axial direction; the lower case
is cup shaped for containing therein the rotor; the resin mold
compound is provided so as to cover over at least a portion of a
circumferential surface and a portion of a bottom surface of the
cup shaped lower case; and a reinforcement board is embedded at a
bottom portion of the cup shaped lower case opposing the rotor
magnet.
19. The pump according to claim 18, wherein: the resin mold
compound has embedded therein a control circuit board below the
stator; the control circuit board has a surface facing the bottom
portion of the cup shaped lower case in the axial direction; and
the reinforcement board is embedded between the bottom portion and
the control circuit board in the axial direction.
20. The pump according to claim 17, wherein the reinforcement board
is formed of a material selected from the group consisting of
stainless steel and aluminum alloy.
21. The pump according to claim 17, wherein: a case side
reinforcement board is embedded for increasing durability of the
case against an internal pressure of the fluid inside the pump
chamber; and the case side reinforcement board is provided at an
area surrounding the intake portion of the case.
22. A pump, comprising: a pump chamber formed inside a case, formed
of a resin material, for forming a pathway for fluid; at least one
intake portion connected to the pump chamber for intaking therein
the fluid; at least one discharge portion connected to the pump
chamber for discharging therefrom the fluid; a rotor located inside
the pump chamber and having therein a rotor magnet, wherein the
rotor rotates along a predetermined rotary shaft; an impeller
rotating along with the rotor so as to direct the fluid to a
predetermined direction; a stator located opposing to the rotor
magnet, while having a gap therebetween, outside of the pump
chamber, wherein the stator includes therein an armature which is a
generator of a magnetic field; a metallic cover affixed, for
increasing durability of the case, to a portion of the case to
which an internal pressure generated by the fluid inside the pump
chamber is applied; and a case side reinforcement board being
embedded for increasing durability of the case against an internal
pressure of the fluid inside the pump chamber, wherein the case
side reinforcement board is provided at an area surrounding the
intake portion of the case.
23. The pump according to claim 22, wherein: the stator includes
therein a resin mold compound having formed therein an armature
molded with the resin material; and the resin mold compound is
located for making contact with an outer surface of the case.
24. A pump, comprising: a pump chamber formed inside a case, formed
of a resin material, for forming a pathway for fluid; at least one
intake portion connected to the pump chamber for intaking therein
the fluid; at least one discharge portion connected to the pump
chamber for discharging therefrom the fluid; a rotor located inside
the pump chamber and having therein a rotor magnet, wherein the
rotor rotates along a predetermined rotary shaft; an impeller
rotating along with the rotor so as to direct the fluid to a
predetermined direction; a stator located opposing to the rotor
magnet, while having a gap therebetween, outside of the pump
chamber; the stator including therein a resin mold compound molding
therein an armature which is a generator of a magnetic field; the
resin mold compound located such that a portion thereof makes
contact with an outer surface of the case; and a filler provided in
a space between the resin mold compound and the outer surface of
the case.
25. The pump 25 according to claim 24, wherein: the case includes
an upper case and a lower case in an axial direction; the lower
case is cup shaped for containing the rotor via a gap surrounding a
circumferential surface and a bottom surface of the rotor magnet in
the rotor; the resin mold compound is provided so as to cover over
at least a portion of a circumferential surface and a portion of a
bottom surface of the cup shaped lower case; and a filler is
provided at a portion of a space between an outer circumferential
surface and a bottom surface of the cup shaped lower case, and an
inner circumferential surface of the resin mold compound.
26. The pump according to claim 24, wherein the filler is provided
covering over a weld line generated on the case and on the resin
mold compound.
27. The pump according to claim 24, wherein the filler is silicon
based.
28. The pump according to claim 1, wherein the metallic cover is
thicker than, approximately, 2 mm.
29. The pump according to claim 1, wherein: the metallic cover is
thinner than, approximately, 2 mm; and the metallic cover has
provided thereon a rib so as to increase durability of the metallic
cover.
30. A pump, comprising: a pump chamber formed inside a case, formed
of a resin material, for forming a pathway for fluid; at least one
intake portion connected to the pump chamber for intaking therein
the fluid; at least one discharge portion connected to the pump
chamber for discharging therefrom the fluid; a rotor located inside
the pump chamber and having therein a rotor magnet, wherein the
rotor rotates along a predetermined rotary shaft; an impeller
rotating along with the rotor so as to direct the fluid to a
predetermined direction; a stator located opposing to the rotor
magnet, while having a gap therebetween, outside of the pump
chamber, wherein the stator includes therein an armature which is a
generator of a magnetic field; and a reinforcement element affixed,
for increasing durability of the case, to a portion of the case to
which an internal pressure generated by the fluid inside the pump
chamber is applied.
31. The pump according to claim 30, wherein: the stator includes
therein a resin mold compound having formed therein an armature
molded with the resin material; and the resin mold compound is
located for making contact with an outer surface of the case.
32. The pump according to claim 1, wherein the pump is used for a
water heater used for a heating system operable to simultaneously
distribute hot water to a plurality of outlets.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Technical Field
[0002] The present invention relates to pumps, and more
particularly to a pump having improved hydraulic pressure
resistance by increasing the durability of the exterior and
interior of the pump, having therein a case formed of a resin
material.
[0003] 2. Description of the Related Art
[0004] There is a growing demand for a device such as a water
heater to become smaller in dimensions, lighter in weight and
energy efficient. Such demand is also expected of a pump installed
in the aforementioned device or the like.
[0005] A pump in general comprises a DC brushless motor having a
rotor which is sealed inside a case, a stator affixed outside the
case for driving the rotor, and an impeller which is connected to
the rotor and is located in a pump chamber therein.
[0006] FIG. 8 is a diagram showing a schematic cross sectional view
in an axial direction of an example of a conventional pump. As
shown in FIG. 8, a pump 100 has arranged therein a rotor 121 in an
interspace between an upper case 111 and a lower case 112 which are
formed of a resin material. The pump 100 also includes an annular
shaped stator 122 along an outer circumferential surface of the
rotor 121. A pump having such configuration is commonly referred to
as a canned type pump.
[0007] The upper case 111 and the lower case 112 sandwich an
O-shaped ring (hereinafter, referred to as an O-ring) 115, and seal
an inner portion of the pump 100. Also, a pump chamber 116 is
provided at an upper portion of the interspace. An intake portion
113 and a discharge portion 117, which are connected to each other
in the pump chamber for, respectively, intaking and discharging
fluid, protrude outwardly from the upper case 111. The
aforementioned configuration is to be formed integrally.
[0008] The rotor 121 is supported and allowed to freely rotate in a
radial direction by a cylinder shaped sleeve 125 located
surrounding a fixed shaft 123 which is affixed at a center of the
pump 100 inside the lower case 112. Also, a thrust washer 124 is
provided at top and bottom portions of the sleeve 125 so as to
support in the axial direction and allow the rotor to freely
rotate.
[0009] The rotor 121 comprises an impeller base portion 126 which
is connected to the sleeve 125, an impeller 127 which is affixed
above the impeller base portion 126, and a rotor magnet 128 which
is surroundingly affixed to the rotor 121. The rotor magnet 128 is
provided within a cup shaped portion 112a in the lower case
112.
[0010] The stator 122 comprises an annular shaped resin mold
compound 133 including therein a molded resin 132 in which a
printed circuit board 131 and an armature 134 which includes
therein an annular shaped laminated core 129 and a coil 130 are
provided.
[0011] The resin mold compound 133 is located on an outer
circumferential surface of the rotor magnet 128 of the rotor 121
and is affixed to the lower case 112. The resin mold compound 133
and the rotor 121 configure the DC brushless motor. When an
electric current is applied to the stator 122 via the printed
circuit board 131 from an external power supply (not shown in the
figures), the impeller 127 rotates along with the rotor 121. Due to
the rotation of the impeller 127, fluid is taken in through the
intake portion 113 to the pump chamber 116. Then, the fluid
pressured by the impeller 127 will be discharged from the discharge
portion 117.
[0012] For the aforementioned pump 100, metallic cases having a
superior durability than the resin based upper case 111 and the
lower case 112 are used so as to sustain expansion, which is caused
by the hydraulic pressure, of the resin based upper case 111 and
the lower case 112, and to improve hydraulic pressure resistance of
the pump 100.
[0013] However, forming a metal plate into a three-dimensional case
by methods such as pressing and welding will be a difficult task.
Further, the pressing process is a costly process. Furthermore,
such pump requires countermeasures against increased weight thereof
and corrosion.
[0014] Also, according to the pump 100 as shown in FIG. 8, at a
contact portion 136 where the lower case 112 and the annular shaped
resin mold compound 133 make contact with each other, the resin
mold compound 133 will be affected, via the lower case 112, by the
pressure which is generated within the pump. When the pressure
within the pump is increased, due to thin resin layers at the
contact portion 136, the resin mold compound 133 may be damaged
(e.g., occurrences of crack). Ultimately, if the pressure
continues, the resin mold compound 133 may be detached from the
lower case 112.
[0015] Also, in the pump 100, a gap S may be generated between an
inner circumferential surface of the resin mold compound 133
affixed to the lower case 112 and an outer circumferential surface
of the lower case 112. Each time the case 112 is affected by the
pressure from the pump, the gap S may be repeatedly widened. Then,
a weld line having a weak connection is likely to be cracked and,
thus, water leakage of the pump 100 may occur.
BRIEF SUMMARY OF THE INVENTION
[0016] The present invention relates to a pump having a structure
in which a metallic cover is attached to a case, which is formed of
a resin material, so as to increase the durability of the pump
having therein the case. Also, the present invention relates to the
pump having a structure in which a reinforcement board is provided
to the case so as to increase the durability of the case inside the
pump. The present invention improves, without any significant
increase in weight and a production cost thereof, hydraulic
pressure resistance of the pump thereby increasing the durability
of the pump.
[0017] Further, since the metallic cover is attached to a resin
mold compound having molded therein an armature, the durability of
the resin mold compound will be increased.
[0018] Furthermore, the metallic cover can be embedded in either
the case or the resin mold compound.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
[0019] FIG. 1 is a diagram showing a schematic cross sectional
view, in an axial direction, of a pump according to a first
embodiment of the present invention.
[0020] FIG. 2 is a diagram showing a plan view of the pump shown in
FIG. 1 as seen from a side of a fluid intake portion.
[0021] FIG. 3 is a diagram showing a plan view, as seen from a side
of, a pump according to a second embodiment of the present
invention.
[0022] FIG. 4 is a diagram showing a schematic cross sectional
view, in the axial direction, of a pump according to a third
embodiment of the present invention.
[0023] FIG. 5 is an enlarged view of a portion A shown in FIG.
4.
[0024] FIG. 6 is a diagram showing a schematic cross sectional
view, in the axial direction, of a pump according to a fourth
embodiment of the present invention.
[0025] FIG. 7 is an enlarged view of a portion B shown in FIG.
6.
[0026] FIG. 8 a diagram showing a schematic cross sectional view,
in the axial direction, of an embodiment of a conventional
pump.
DETAILED DESCRIPTION OF THE INVENTION
[0027] Hereinafter, embodiments of a pump according to the present
invention will be described with reference to FIGS.
First Embodiment
[0028] FIG. 1 is a diagram showing a schematic cross sectional view
in an axial direction of a pump 10 according to a first embodiment
of the present invention. FIG. 2 is a plan view of FIG. 1. As shown
in FIG. 1, the pump 10 comprises: an upper case 11 and a lower case
12, which are formed of a resin material; a rotor 21 which rotates
around a predetermined central axis J1, and which is located in a
space generated between the upper case 11 and the lower case 12
which are joined together; and a ring shaped stator 22 which is
located along an outer circumference of the rotor 21 and outside of
the lower case 12. The pump 10 is commonly referred to as a canned
type pump wherein the lower case 12 is provided between the rotor
21 and the stator 22. Note that, in the description of the
preferred embodiments of the present invention herein, words such
as upper, lower, left, right, upward, downward, top, and bottom for
describing positional relationships between respective members and
directions merely indicate positional relationships and directions
in the drawings. Such words do not indicate positional
relationships and directions of the members mounted in an actual
device.
[0029] The upper case 11 and the lower case 12 sandwich an O-ring
15, and seal an inner portion of the pump 10. At an upper portion
of an interspace portion generated by the upper case 11 and the
lower case 12, a pump chamber 16 is provided. An intake portion 13
and a discharge portion 17 which are connected to each other in the
pump chamber 16 protrude outwardly from the upper case 11. The
aforementioned configuration is to be formed integrally.
[0030] The rotor 21, sharing the same axis as the central axis J1,
is supported and allowed to freely rotate, via a sleeve 25 and a
thrust washer 24 located at both top and bottom of the sleeve 25,
by a stator shaft 23 fixed between the upper and lower cases 11 and
12.
[0031] The rotor 21 comprises: an impeller ba1se portion 26 which
is connected to the sleeve 25 formed of the resin material (e.g.,
polyphenylene sulfide) having a tribological property; an impeller
27 which is connected to a top portion of the impeller base portion
26; and a rotor magnet 28 which is located surrounding the sleeve
25. The rotor magnet 28 is located inside a cup shaped area
provided in a center portion of the lower case 12.
[0032] The stator 22 comprises: an armature 30 including therein an
annular shaped laminated core 29 and a coil 29a; and a printed
circuit board 31. The printed circuit board 31 and the armature 30
are molded in a molded resin 32 configuring an annular shaped resin
mold compound 33.
[0033] The resin mold compound 33 is located on an outer surface of
the lower case 12 which is located along an outer circumferential
surface of the rotor magnet 28 in the rotor 21. The resin mold
compound 33 is affixed to, so as to cover, an outer circumferential
surface and a portion of a bottom of the cup shaped lower case 12.
Further, the resin mold compound 33 extends radially outwardly from
the cup shaped lower case 12 is affixed to, so as to cover, an
outer surface forming the pump chamber 16. Since the outer surface
of the lower case 12 and the resin mold compound 33 make contact
with each other as described above, the resin mold compound 33 is
able to sustain expansion of the lower case 12 even if the pressure
within the lower case 12 is increased.
[0034] The motor according to the present invention is a component
of the brushless DC motor such that when the stator 22 is supplied
with an electric current from the printed circuit board 31, a
rotating magnetic field will be generated in the stator 22, thereby
rotating the rotor 21. When the rotor 21 rotates, the impeller 27
connected to the rotor 21 rotates. Then the fluid will be sucked in
to the inner portion of the pump chamber 16 through the intake
portion 13, directed by the impeller 27 to flow in a predetermined
direction, and discharged through the discharge portion 17.
[0035] In the pump 10 according to the present embodiment, an
annular shaped metallic cover 1 is provided covering over an outer
surface of the upper case 11. The metallic cover 11 is secured by a
screw 2 at four points to the upper case 11. Here, the screws 2
each are to be used at points avoiding the pump chamber 16 so as to
avoid exposing the screws 2 to the inner portion of the pump
chamber 16. If the screws 2 are exposed to the inner portion of the
pump chamber 16, the fluid inside the inner portion may leak
outside thereof. Also, if screws 2 not long enough to penetrate the
metallic cover 1 are used, the metallic cover 1 will not be secured
to the upper case 11. Also, providing a layer having an increased
thickness for the upper case 11 so that long screws 2 can be used,
the dimensions of the pump 10 will be large. In order to solve the
aforementioned problems, the screws 2 are provided ideally at
points avoiding the pump chamber 16.
[0036] In general, in a pump, which has a case formed of a resin
material, whose rated total head is approximately 13 m or smaller,
and whose rated flow is approximately 30 L/min or smaller, a
maximum internal pressure of fluid a pump chamber can withstand is
between, approximately, 200 KPa to 250 KPa. When the internal
pressure is to be greater than 250 KPa, a metallic case will be
necessary in order to sustain the expansion. However, when the
upper case 11, which is formed of the resin material, has applied
thereon the metallic cover 1 in the pump 10 according to the
present embodiment, an internal pressure up to approximately 1000
KPa can be withstood. Therefore, the pump 10 can be used for a pump
in which the internal pressure of the fluid in a pump chamber
exceeds approximately 250 KPa.
[0037] The metallic cover 1 provides an opening 3 for insertion of
the intake portion 13 which protrudes from the upper case 11. Also,
the metallic cover 1 can be easily manufactured by pressing a
stainless steel plate or an aluminum base plate. Also, the metallic
cover 1 can be attached to the pump 10 easily. Also, the metallic
cover 1 is attached, to the upper case 11, stretching over a weld
line (not shown in the figures) which is generated when the upper
case 11 is formed by a die. Since the upper case 11 is most
vulnerable at the weld line, when the metallic cover 1 is affixed
covering over the weld line on the upper case 11, damages (e.g.,
occurrence of crack or expansion) can be prevented.
[0038] The metallic cover 1 is to be secured by the screw 2 at, at
least, one point on both sides of the weld line. By this, the
metallic cover 1 will be able to prevent damages from being done to
the weld line even when the internal pressure within the pump
chamber 16 increases.
[0039] The metallic cover 1 increases the durability of the pump 10
having therein the upper case 11 and the lower case 12, which are
formed of the resin material, to an extent of the durability of a
pump having therein a metallic case. Further, the metallic cover 1
can easily be manufactured and attached to the cases while keeping
a weight increase of the pump 10 to a minimum. Further, the
metallic cover 1 can increase the durability of upper case 11 which
is repeatedly pressured by the internal pressure of the fluid
inside the pump chamber 16. As a result, a pump having the metallic
cover 1 will last long and have an increased durability.
[0040] Further, a metallic cover different from the metallic cover
1 can be provided on a surface, of the lower case 12, making
contact with the armature 30 in the axial direction. Note that the
non-metallic-cover-1-metallic-cover provides an opening for
insertion of the cup shaped lower case 12. By this, the lower case
12 can be sandwiched from both sides thereof in the axial
direction, thereby constrictedly securing the pump chamber 16. By
this, the durability of the pump 10 against the internal pressure
of the fluid within the pump chamber 16 will be increased.
Second Embodiment
[0041] Next, a pump according to a second embodiment of the present
invention will be described with reference to FIG. 3. FIG. 3 is a
diagram showing a plan view, as seen from a side of, a pump
according to a second embodiment of the present invention. In FIG.
3, elements similar to those illustrated in FIG. 1 are denoted by
similar reference numerals, and description thereof is omitted.
[0042] In the first embodiment, the metallic cover 1 covers over
only the top surface in the axial direction of the upper case 11.
In the second embodiment, however, a metallic cover is provided on
both top and bottom surfaces of a pump 70 so as to sandwich, and to
provide additional durability, to the pump 70. That is, according
to FIG. 3, a metallic cover 71 which covers over a top surface of
the upper case 11 and a resin mold compound side metallic cover 72
which covers over a bottom surface of the resin mold compound 33
are provided on the upper case 11. The metallic cover 71 and the
resin mold compound side metallic cover 72 each are secured to the
upper case 11 at four points by a screw 73. A cylinder shaped
collar 78 is provided between the resin mold compound side metallic
cover 72 and the resin mold compound 33. The resin mold compound
side metallic cover 72 and the resin mold compound 33 each have
predetermined points (not shown in the figures) for the screw 73.
Also, the upper case 11 and the metallic cover 71 each have
predetermined points (not shown in the figures) for the screw 73.
Since the metallic cover 71 and the resin mold compound side
metallic cover 72 are provided, the durability of the upper case 11
and the resin mold compound 33 will be increased. In particular,
the resin mold compound side metallic cover 72 affixed to the resin
mold compound 33 increases the durability of the resin mold
compound 33 so as for the resin mold compound 33 to withstand
greater internal pressure of fluid within the pump chamber 16 than
the resin mold compound 33 without the resin mold compound side
metallic cover 72.
[0043] Note that, a planar shape of the metallic cover 71 and that
of the resin mold compound side metallic cover 72 may be adjusted
(e.g., round shape, substantially rectangle, or square) in
accordance with a configuration of the pump.
[0044] Also, the metallic cover 71 and the resin mold compound side
metallic cover 72 are affixed to a pump base 80 by a plurality of
screws 82. The pump base 80 is used to mount the pump 70 onto an
apparatus. The pump base 80 has an extension portion 81, which
extends toward the metallic cover 71 and toward the resin mold
compound side metallic cover 72. A portion of the extension portion
81 overlaps with a portion of the metallic cover 72 and with a
portion of the resin mold compound side metallic cover 72. At the
portions where the extension portion 81 and metallic cover 72
overlap one another, and where the extension portion 81 and the
resin mold compound side metallic cover 72 overlap one another,
openings 83 for insertion of the screws 82 are provided. The pump
base 80 is formed by pressing a metal plate. That is, the pump base
80 can be manufactured inexpensively.
[0045] Since a primary object of the pump base 80 is to facilitate
the connection between the pump 70 and the apparatus (not shown in
the figures) onto which the pump 70 is to be mounted, the metallic
cover 71 and the resin mold compound side metallic cover 72 are not
designed to withstand a great amount of pressure. However, the
metallic cover 71 and the resin mold compound side metallic cover
72 need to sustain expansion which may occur to the upper case 11
and the resin mold compound 33, and therefore durability thereof
against the pressure need to be increased. Thus, the metallic cover
71 and the resin mold compound side metallic cover 72 are designed
to be thicker than a thickness of the plate forming the pump base
80. The thickness of the metallic cover 71 and that of the resin
mold compound side metallic cover 72 each are, preferably, greater
than, approximately, 2 mm. When the thickness of the metallic cover
71 and that of the resin mold compound side metallic cover 72 each
are greater than approximately 2 mm, the metallic cover 71 and the
resin mold compound side metallic cover 72 can sustain an
expansion, of the uppercase 11 and the resin mold compound 33,
caused by the internal pressure within the pump chamber 16. When
the metallic cover 71 and the resin mold compound side metallic
cover 72 each having a thickness smaller than, approximately, 2 mm
are used, it is preferable that a rib is provided to the metallic
cover 71 and the resin mold compound side metallic cover 72 in
order to increase the durability of the metallic cover 71 and the
resin mold compound side metallic cover 72. When such rib is
provided to the metallic cover 71 and the resin mold compound side
metallic cover 72 each having the thickness smaller than
approximately 2 mm, the metallic cover 71 and the resin mold
compound side metallic cover 72 will have the durability equivalent
to that of the metallic cover 71 and the resin mold compound side
metallic cover 72 having the thickness of, or greater than,
approximately 2 mm.
[0046] Also, the metallic cover 71 and the resin mold compound side
metallic cover 72 have preferably a same shape with one another.
When the metallic cover 71 and the resin mold compound side
metallic cover 72 have the same shape, they can be manufactured by
using the same die, thereby reducing the production cost thereof.
That is, pumps according to the present embodiment can be provided
at low cost. When the metallic cover 71 and the resin mold compound
side metallic cover 72 are manufactured by using the same die, the
resin mold compound side metallic cover 72 will have an opening for
the intake portion and an opening for a drainage plug in a same
manner as the metallic cover 71. In order to prevent the resin mold
compound 33 from being exposed externally through the openings and
to increase the durability of the resin mold compound 33, a rib
will be provided to the openings.
Third Embodiment
[0047] FIG. 4 is a diagram showing a schematic cross sectional view
in the axial direction of a pump 50 according to a third embodiment
of the present invention. FIG. 5 is an enlarged view of a portion A
shown in FIG. 4. As shown in FIG. 4, the pump 50 is a canned type
pump, wherein the pump 50 has a common structure as the pump 10
according to the first embodiment. In FIG. 4, elements similar to
those illustrated in FIG. 1 are denoted by similar reference
numerals, and the description of the structure of the pump 50 is
omitted.
[0048] The pump 50 according to the third embodiment comprises a
stator 22 including an annular shaped resin mold compound 34 having
therein the molded resin 32 in which the armature 30 and the
printed circuit board 31 are provided. In the armature 30, the ring
shaped laminated core 29 and the coil 29a are provided.
[0049] The resin mold compound 34 includes therein an annular
shaped reinforcement board 5 which is formed of a metal plate. The
reinforcement board 5 is located at a molded resin portion 32a, in
the resin mold compound 34, between a cup shaped bottom portion 35
and the lower case 12. The contact between the resin mold compound
34 and the lower case 12 is similar to the contact between the
resin mold compound 33 and the lower case 12 according to the first
embodiment.
[0050] The reinforcement board 5 which is formed of a non-magnetic
material (e.g., stainless steel or aluminum alloy). The
reinforcement board 5 is formed by embedding (e.g., insert molding)
in the molded resin 32 when the resin mold compound 34 is formed by
molding the stator 22 and the printed circuit board 31. The
reinforcement board 5 is located near or attached to an electronic
component which is mounted on the printed circuit board 31 and
emits heat so as for the electronic component to alleviate the
heat.
[0051] The reinforcement board 5 can: increase the durability of
the molded resin portion 32a having an inferior durability compared
with the rest of the molded resin 32; and alleviate the pressure
conducted to the resin mold compound 34 from the bottom portion 35.
That is, the reinforcement board 5 prevents damages (e.g.,
occurrence of crack) from being done to the resin mold compound 34,
thereby preventing the stator 22 from being damaged, and prevents
the resin mold compound 34 from being detached from the lower case
12.
[0052] Also, in order to increase the durability of the pump 50, an
annular shaped reinforcement board 18 is provided by an insertion
molding so as to surround a protruding portion of the intake
portion 13.
Fourth Embodiment
[0053] FIG. 6 is a diagram showing a schematic cross sectional view
in the axial direction of a pump 60 according to a fourth
embodiment of the present invention. FIG. 7 is a diagram showing an
enlarged portion B shown in FIG. 6. The pump 60 as shown in FIG. 6
is a canned type pump having a common structure as the pumps 10 and
50, respectively, according to the first and the third embodiments.
In FIG. 6, elements similar to those illustrated in FIG. 4 are
denoted by similar reference numerals, and the description of the
structure of the pump 60 is omitted.
[0054] The pump 60 according to the fourth embodiment comprises,
similarly as the pump 10 described above, the stator 22 and the
printed circuit board 31 which are molded in the molded resin 32
forming the annular shaped resin mold compound 33, wherein the
stator 22 includes the ring shaped laminated core 29 and the
coil.
[0055] The resin mold compound 33 is affixed along the outer
circumferential surface of the rotor magnet 28 of the rotor 21, and
along the outer circumferential surface of the lower case 12. There
is a minute gap S between the inner circumferential surface of the
resin mold compound 33 and the outer circumferential surface of the
lower case 12.
[0056] A filler 6 is provided in the gap S between the resin mold
compound 33 and the lower case 12 of the pump 60 according to the
present embodiment of the invention. The filler 6 is provided by
applying it on the internal circumferential surface of the resin
mold compound 33 and/or the outer circumferential surface of the
lower case 12 before the resin mold compound 33 is attached to the
lower case 12.
[0057] The filler 6 may be an oil, a rubber or a resin substance. A
silicon (e.g., rubber or resin) filler is beneficial in that, when
applied on the lower case 12, the expansion of the lower case 12
can be sustained. Also, the silicon case 12 can be easily applied
and is inexpensive.
[0058] By this, the expansion of the lower case 12 due to the
internal pressure of the fluid within the pump chamber 16 can be
sustained, thereby preventing the occurrence of a crack at the weld
line of the lower case 12.
[0059] As described above, the pump according to the present
invention provides: (1) the metallic cover 1 on the surface of the
upper case formed of the resin material; (2) the metallic cover 1
on the surface of the upper case 11 and on the surface of the resin
mold compound 33; (3) the reinforcement board 5 in the resin mold
compound 33 at the portion thereof where the resin mold compound 33
and the lower case 12 make contact with each other; and (4) the
filler 6 in the gap S between resin mold compound 33 and the lower
case 12. Note, however, that aforementioned 4 elements each can be
applied separately or simultaneously.
[0060] While the invention has been described in detail, the
foregoing description is in all aspects illustrative and not
restrictive. It is understood that numerous other modifications and
variations can be devised without departing from the scope of the
invention. Further, the present invention can be applied to an
automatic feed water pump, an axial pump, or to a pump commonly
referred to as a reversible pump, having therein a plurality of
discharge portions, in which fluid inside the pump is directed to a
predetermined discharge portion by an impeller provided
therein.
[0061] Further, the stator 22 according to the present invention is
not necessarily limited to as described above. The stator 22 can be
formed by, after attaching the armature 30 to the lower case 12,
filling a space, which is generated by an exterior wall integrally
formed with the lower case 12, with a potting material. The space
generated by the exterior wall can be provided separately from the
lower case 12 or can be attached to the uppercase 11.
[0062] Although the forgoing description assumes that a metallic
plate (e.g., metallic cover and reinforcement board) is, in order
to reinforce the durability of the pump, provided to the upper case
the lower case and the resin mold compound, this is not limited
thereto. Since an object of the invention is to provide an element
to the upper case, the lower case and the resin mold compound so as
to increase the durability of the upper case, the lower case and
the resin mold compound, the element can be formed of a resin
material having a high degree of hardness or a carbon fiber. For
example, a reinforcement element for covering over the upper case,
the lower case and the resin mold compound can be in any shape if
the element is able to cover over the lower case and the resin mold
compound.
[0063] The pump according to the present invention can be used for
a water heater which is used for a heating system, a bath room and
a kitchen.
* * * * *