U.S. patent application number 16/558204 was filed with the patent office on 2020-03-19 for electric pump.
This patent application is currently assigned to AISAN KOGYO KABUSHIKI KAISHA. The applicant listed for this patent is AISAN KOGYO KABUSHIKI KAISHA. Invention is credited to Yoshihiko HONDA, Naoki SHIRAI, Shota TSUKAMOTO.
Application Number | 20200088182 16/558204 |
Document ID | / |
Family ID | 69774413 |
Filed Date | 2020-03-19 |
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United States Patent
Application |
20200088182 |
Kind Code |
A1 |
HONDA; Yoshihiko ; et
al. |
March 19, 2020 |
Electric Pump
Abstract
An electric pump includes a first housing member, a second
housing member, and a partition. The first housing member includes
a first support surface and a first seal surface. The second
housing member includes a second support surface and a second seal
surface. The partition is directly held between the first support
surface and the second support surface to form a pump chamber with
the first housing member and to form a motor chamber with the
second housing member. The motor chamber houses a motor that
includes a stator and a rotor. The pump chamber houses an impeller.
The partition supports a bearing for holding a rotation shaft
coupled to the rotor and the impeller. The first seal surface and
the second seal surface directly hold a seal member
therebetween.
Inventors: |
HONDA; Yoshihiko; (Obu-shi,
JP) ; TSUKAMOTO; Shota; (Kariya-shi, JP) ;
SHIRAI; Naoki; (Toyohashi-shi, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
AISAN KOGYO KABUSHIKI KAISHA |
Obu-shi |
|
JP |
|
|
Assignee: |
AISAN KOGYO KABUSHIKI
KAISHA
Obu-shi
JP
|
Family ID: |
69774413 |
Appl. No.: |
16/558204 |
Filed: |
September 2, 2019 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F04C 2240/20 20130101;
F04D 29/426 20130101; F04D 13/0653 20130101; F04C 29/068 20130101;
F04C 2240/10 20130101; F04D 29/5806 20130101; F04D 29/628 20130101;
F04C 2240/30 20130101; F04B 39/121 20130101 |
International
Class: |
F04B 39/12 20060101
F04B039/12; F04C 29/06 20060101 F04C029/06 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 13, 2018 |
JP |
2018-171460 |
Claims
1. An electric pump, comprising: a first housing member including a
first support surface and a first seal surface; a second housing
member including a second support surface and a second seal
surface; a partition directly held between the first support
surface and the second support surface, the partition, wherein a
pump chamber is disposed between the partition and the first
housing member and a motor chamber is disposed between the
partition and the second housing member; a motor disposed in the
motor chamber and including a stator and a rotor; an impeller
disposed in the pump chamber; a bearing supported by the partition;
and a rotation shaft supported by the bearing and coupled to the
rotor and the impeller, and a seal member directly contacting the
first seal surface and the second seal surface.
2. The electric pump according to claim 1, wherein: the first
support surface is closer to the pump chamber than the first seal
surface; and the second support surface is closer to the motor
chamber than the second seal surface.
3. The electric pump according to claim 1, wherein: the first
housing member includes a concave part; the second housing member
includes a convex part that faces the concave part to form a space
having a bent part therebetween; the first support surface and the
first seal surface are separated from each other by the bent part;
and the second support surface and the second seal surface are
separated from each other by the bent part.
4. The electric pump according to claim 1, wherein the partition is
made from a metal material and comprises: a bearing support part
directly supporting the bearing; and a pipe part housing the stator
and the rotor therein.
5. The elastic pump according to claim 4, wherein: the pipe part
includes a first end, the partition includes an elastic part
coupling the bearing support part to the first end of the pipe
part; and the elastic part is configured to be elastically deformed
when vibrations are transmitted from the rotation shaft to the
elastic part via the bearing support part.
6. The electric pump according to claim 5, wherein the elastic part
of the partition has a bending rigidity that is less than a bending
rigidity of the bearing support part and a bending rigidity of the
pipe part.
7. The electric pump according to claim 5, wherein: the pipe part
of the partition includes a second end positioned opposite to the
first end and a flange part protruding radially outward from the
second end; the flange part engages with the first housing member
in an axial direction of the rotation shaft; and the elastic part
comprises at least one support part being elastically deformable
and contacting the stator in the axial direction.
8. The elastic pump according to claim 7, wherein: the elastic part
comprises at least one opening; and the at least one support part
extends from an edge of the at least one opening.
9. The electric pump according to claim 8, wherein the at least one
support part includes a guide surface extending in a
circumferential direction about an axis of the rotation shaft and
forming a flow path from the pump chamber into the motor chamber
through the at least one opening.
10. The electric pump according to claim 7, wherein the at least
one support part includes three or more support parts.
11. The electric pump according to claim 4, further comprising: a
circuit board electrically coupled to the stator and positioned on
a side of the second housing member opposite the motor chamber,
wherein a dimension of the circuit board in a direction
perpendicular to an axis of the rotation shaft is smaller than an
inner diameter of the pipe part of the partition.
12. The electric pump according to claim 11, further comprising: a
plurality of spacers disposed between the stator and the pipe part
of the partition, wherein the spacers are circumferentially spaced
about the axis of the rotation shaft to form therebetween a
plurality of circumferentially spaced curved spaces.
13. The electric pump according to claim 12, further comprising: a
coil terminal extending through one of the curved spaces; wherein:
the stator includes a plurality of circumferentially arranged
stator coils; and the coil terminal electrically connects the
circuit board with one of the stator coils.
14. The electric pump according to claim 11, further comprising: a
rear cover positioned on a side of the circuit board away from the
motor chamber, wherein the rear cover is electrically coupled to
the partition and has a dimension larger than the inner diameter of
the pipe part of the partition in the direction perpendicular to
the axis of the rotation shaft.
15. The electric pump according to claim 4, wherein: the stator
includes an inward facing surface directed to the rotor; and the
bearing support part is disposed along the inward facing surface of
the stator.
16. The electric pump according to claim 1, wherein: the first
housing member includes an open end sized and configured to receive
the impeller, the partition, and the motor therethrough and into
the first housing member; and the open end of the first housing
member is closed with the second housing member.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority to Japanese patent
application serial number 2018-171460, filed Sep. 13, 2018, which
is hereby incorporated herein by reference in its entirety for all
purposes.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
[0002] Not applicable.
BACKGROUND
[0003] This disclosure relates to electric pumps.
[0004] Some electric pumps include a pump-side cover and a
motor-side cover. The pump-side cover and the motor-side cover are
coupled to each other to form an interior space that is divided by
a partition plate into a pump chamber and a motor chamber. The pump
chamber houses an impeller therein. The motor chamber houses a
stator and a rotor therein. The impeller is coupled to the rotor
via a rotation shaft that is supported by a bearing. The bearing is
fitted in a through hole formed in the partition plate.
[0005] Two O-rings may be provided at joint portions between the
pump-side cover and the motor-side cover. One of the O-rings is
disposed between the pump-side cover and the partition plate. The
other O-ring is disposed between the motor-side cover and the
partition plate.
BRIEF SUMMARY
[0006] In one aspect of this disclosure, an electric pump includes
a first housing member, a second housing member and a partition.
The first housing member includes a first support surface and a
first seal surface. The second housing member includes a second
support surface and a second seal surface. The partition is
directly held between the first support surface and the second
support surface to form a pump chamber with the first housing
member and to form a motor chamber with the second housing. The
motor chamber houses therein a motor including a stator and a
rotor. The pump chamber houses an impeller therein. The partition
supports a bearing for holding a rotation shaft that is coupled
with the rotor and the impeller. The first seal surface and the
second seal surface directly hold a seal member therebetween.
[0007] According to this aspect, the seal member directly held
between the first seal surface and the second seal surface, and the
partition is held between the first support surface and the second
support surface. Thus, the first housing member and the second
housing member can stably support the partition plate without being
substantially influenced by the seal member. Accordingly, the
impeller supported by the partition via the bearing and the
rotation shaft can be stabilized at a desirable position.
Therefore, vibration generated by rotation of the rotor can be
reduced so as to suppress pulsations in discharge pressure of the
electric pump.
[0008] Other objects, features and advantage of the present
teaching will be readily understood after reading the following
detailed description together with the accompanying drawings and
the claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] For a detailed description of the preferred embodiments of
the present teaching, reference will now be made to the
accompanying drawings.
[0010] FIG. 1 is a perspective view of an electric pump according
to a first embodiment.
[0011] FIG. 2 is a side view of the electric pump of FIG. 1.
[0012] FIG. 3 is a top view of the electric pump of FIG. 1.
[0013] FIG. 4 is a schematic cross-sectional view of the electric
pump of FIG. 1 taken along section IV-IV of FIG. 3.
[0014] FIG. 5 is an enlarged partial cross-sectional view of the
electric pump of FIG. 1 illustrating region V of FIG. 4.
[0015] FIG. 6 is a cross-sectional view of the electric pump of
FIG. 1 taken along section VI-VI of FIG. 4.
[0016] FIG. 7 is a schematic cross-sectional view of an electric
pump according to a second embodiment.
[0017] FIG. 8 is a schematic cross-sectional view of an electric
pump according to a third embodiment.
[0018] FIG. 9 is a schematic cross-sectional view of an electric
pump according to a fourth embodiment.
[0019] FIG. 10 is a cross-sectional view of the electric pump of
FIG. 9 taken along section X-X of FIG. 9.
[0020] FIG. 11 is a cross-sectional view of the electric pump of
FIG. 9 taken along section XI-XI of FIG. 10.
[0021] FIG. 12 is a schematic cross-sectional view of an electric
pump according to a fifth embodiment.
[0022] FIG. 13 is a schematic cross-sectional view of an electric
pump according to a sixth embodiment.
[0023] FIG. 14 is an enlarged partial cross-sectional view of the
electric pump of FIG. 13 illustrating region XIV of FIG. 13.
[0024] FIG. 15 is a schematic cross-sectional view of an electric
pump according to seventh embodiment.
DETAILED DESCRIPTION
[0025] The following discussion is directed to various exemplary
embodiments. However, one skilled in the art will understand that
the examples disclosed herein have broad application, and that the
discussion of any embodiment is meant only to be exemplary of that
embodiment, and not intended to suggest that the scope of the
disclosure, including the claims, is limited to that
embodiment.
[0026] Certain terms are used throughout the following description
and claims to refer to particular features or components. As one
skilled in the art will appreciate, different people may refer to
the same feature or component by different names. This document
does not intend to distinguish between components or features that
differ in name but not function. The drawing figures are not
necessarily to scale. Certain features and components herein may be
shown exaggerated in scale or in somewhat schematic form and some
details of conventional elements may not be shown in interest of
clarity and conciseness.
[0027] In the following discussion and in the claims, the terms
"including" and "comprising" are used in an open-ended fashion, and
thus should be interpreted to mean "including, but not limited to .
. . ." Also, the term "couple" or "couples" is intended to mean
either an indirect or direct connection. Thus, if a first device
couples to a second device, that connection may be through a direct
connection, or through an indirect connection via other devices,
components, and connections.
[0028] Each of the additional features and teachings disclosed
above and below may be utilized separately or in conjunction with
other features and teachings to provide improved electric pumps.
Representative examples of the present teachings, which examples
utilized many of these additional features and teachings both
separately and in conjunction with one another, will now be
described in detail with reference to the attached drawings. This
detailed description is merely intended to teach a person skilled
in the art further details for practicing preferred aspects of the
present teachings and is not intended to limit the scope of the
claimed subject-matter. Only the claims define the scope of the
claimed subject-matter. Therefore, combinations of features and
steps disclosed in the following detailed description may not be
necessary to practice the claimed subject-matter in the broadest
sense, and are instead taught merely to particularly describe
representative examples of the present teachings. Moreover, various
features of the representative examples and the dependent claims
may be combined in ways that are not specifically enumerated in
order to provide additional useful embodiments of the present
teachings.
[0029] In conventional electric motors as described above, it is
very difficult if not impossible to completely eliminate rotational
unbalance of the rotor. Accordingly, when the rotor is rotated at
high speed, the rotation shaft vibrates due to the rotational
unbalance of the rotor. This vibration is transmitted to the
impeller, thereby resulting in the generation of undesirable pulses
in the discharge pressure of the electric pump. Therefore, there
has been a need for improved electric pumps.
[0030] A first embodiment of the present disclosure will be
described with reference to FIGS. 1 to 6. An electric pump
according to the first embodiment is a purge pump 1 that is
incorporated in an evaporative emission system of a vehicle
equipped with an internal combustion engine, such as in an
automobile. In each drawing, an arrow F defines a frontward
direction of the purge pump 1, and an arrow B defines a rearward
direction thereof.
[0031] As shown in FIG. 4, the purge pump 1 includes an impeller 20
and a brushless motor 45. The impeller 20 is coupled to a rotation
shaft 41 of the brushless motor 45. The brushless motor 45 includes
a rotor 40 and a stator 50. The rotor 40 is composed of magnetic
members, such as permanent magnets. The stator 50 includes a stator
core 51 and stator coils 52.
[0032] The brushless motor 45 and the impeller 20 are covered with
a front cover 11 and a stator body 12, such that the brushless
motor 45 and the impeller 20 are housed in an interior space formed
by the front cover 11 and the stator body 12. That is, each of the
front cover 11 and the stator body 12 serves as a housing member
forming the interior space for the impeller 20 and the brushless
motor 45. The interior space defined by the front cover 11 and the
stator body 12 is divided by a partition plate 30 into a front-side
space and a rear-side space. The front-side space houses the
impeller 20 therein and is referred to herein as "pump chamber" The
rear-side space houses the stator 50 and the rotor 40 therein and
is referred to herein as "motor chamber" The stator body 12 may be
made from a resin material by insert molding to integrally include
a molded part 53 integrated with the stator core 51 and the stator
coils 52. That is, a part of the stator body 12 serves as the
housing member, and another part of the stator body 12, for example
the molded part 53, corresponds to a part of the stator 50.
[0033] As shown in FIGS. 1 to 4, in this embodiment, the front
cover 11 has a stepped hollow cylindrical shape with a front plate
narrowing a front opening thereof and may be made from a resin
material. The front cover 11 includes an inlet port 11a and an
outlet port 11b. The inlet port 11a extends frontward from the
front plate of the front cover 11, such that the inlet port 11a is
coaxially aligned with the impeller 20. The outlet port 11b extends
outward from an outer circumference of the front cover 11, along a
plane oriented perpendicular to the axis of the inlet port 11a.
More specifically, the outlet port 11b extends in the tangential
direction from the outer periphery of the impeller 20. Thus, when
the impeller 20 is rotated, the purge pump 1 suctions fuel vapor
from the evaporative emission system (not shown) via the inlet port
11a and then discharges it from the outlet port 11b for supplying
the fuel vapor to the internal combustion engine (not shown).
[0034] The partition plate 30 may be made from a metal material
exhibiting heat conductivity and electric conductivity, and
includes a bearing support part 31, an outer pipe part 32, and an
elastic part 33. The outer pipe part 32 has a hollow cylindrical
shape and is fitted within the hollow cylindrical portion of the
front cover 11 surrounding the stator 50 in a radial direction
perpendicular to the rotation shaft 41. The bearing support part 31
has a hollow cylindrical shape. The elastic part 33 has an annular
plate shape extending radially from a front end of the bearing
support part 31 to a front end of the outer pipe part 32. The
bearing support part 31 receives bearings 42 therein and supports
the outer circumferences of the bearings 42. The bearings 42 are
disposed between the impeller 20 and the rotor 40 in the front-rear
direction and rotatably support the rotation shaft 41.
[0035] The bearing support part 31 is coupled to the outer pipe
part 32 via the elastic part 33. The elastic part 33 is configured
to be elastically deformed when vibrations are transmitted from the
rotation shaft 41 to the elastic part 33 via the bearing support
part 31. More specifically, the elastic part 33 has a shape, for
instance a relatively thin flat shape, which more easily deforms
compared with the bearing support part 31 and the outer pipe part
32. That is, the elastic part 33 has a bending rigidity that is
less than that of the bearing support part 31 and the outer pipe
part 32. Because the elastic part 33 is shaped and configured to
achieve the low bending rigidity, complicated structures of the
partition plate 30 can be avoided.
[0036] Due to the foregoing configuration, when the heat generated
by the bearings 42 is transmitted to the elastic part 33 via the
bearing support part 31, the heat is transmitted from the elastic
part 33 to the fluid being moved by the impeller 20. In addition,
the outer pipe part 32 can reduce and/or prevent leakage of noise
(e.g., acoustic waves) emitted from the brushless motor 45, and
more specifically the stator coils 52. Further, when vibrations of
the rotation shaft 41 are transmitted to the elastic part 33, the
elastic part 33 is elastically deformed so as to absorb and thereby
reduce the vibrational energy. Thus, pulsations in the discharge
pressure of the purge pump 1, which are caused by vibrations of the
rotation shaft 41, can be reduced. Meanwhile, the partition plate
30 has a high bending rigidity part near the outer pipe part 32 and
in rear of a volute part 21 radially outside the impeller 20. Thus,
even if the fluid pressure in the volute part 21 becomes high, the
amount of deflection of the partition plate 30 will be relatively
small. Accordingly, the distance between the impeller 20 and the
partition plate 30 can be kept at nearly a constant value, thereby
further reducing generation of the pulsations in the discharge
pressure of the purge pump 1.
[0037] The partition plate 30 includes a flange part 30a extending
radially outward from a rear end of the outer pipe part 32. The
front cover 11 also include a flange part 11c extending radially
outward from a rear end of the cylindrical portion of the front
cover 11 and bending rearward. The flange part 30a is held between
an inner circumference of the flange part 11c of the front cover 11
and a front surface of a flange part 12a formed at an outer
periphery of the stator body 12.
[0038] As shown in FIG. 5, the front cover 11 includes a concave
part 11d recessed from an inner circumference thereof. The concave
part 11d includes a first support surface 11e facing rearward and a
first sealing surface 11f facing radially inward. As shown in FIG.
4, the stator body 12 includes a convex part 12b projecting forward
from the front surface of the flange part 12a. As shown in FIG. 5,
the convex part 12b includes a second support surface 12c facing
forward and a second sealing surface 12d facing radially outward.
The convex part 12b of the stator body 12 is disposed to face the
concave part 11d such that the first support surface 11e and the
second support surface 12c face each other, and further, such that
the first sealing surface 11f and the second sealing surfaces 12d
face each other. The concave part 11d and the convex part 12b
define a space 13 including a bent part 13a that essentially
divides the first support surface 11e and the first sealing surface
11f. The bent part 13a also essentially divides the second support
surface 12c from the second sealing surface 12d. The first support
surface 11e and the second support surface 12c directly support the
flange part 30a of the partition plate 30 therebetween, such that a
leading edge of the flange part 30a is disposed in the bent part
13a. Meanwhile, the first sealing surface 11f and the second
sealing surface 12d directly support an O-ring 71 therebetween. The
O-ring 71 functions as a sealing member to seal the space 13
between the front cover 11 and the stator body 12.
[0039] As described above, the convex part 12b and the concave part
11d support the flange part 30a of the partition plate 30 and hold
the O-ring 71. However, these components are being supported and
held at positions different from each other. Thus, the partition
plate 30 supporting the bearings 42 is stably supported and held
between the support surfaces 11e, 12c without being influenced by
the O-ring 71. Thus, the impeller 20 supported by the partition
plate 30 via the bearing 42 can be stabilized at a predetermined
position. Further, the partition plate 30 can decrease vibrations,
which are generated by rotation of the rotor 40, of the rotation
shaft 41 so as to reduce the pulsations in the discharge pressure
of the purge pump 1.
[0040] The O-ring 71 is held between the front cover 11 and the
stator body 12. The partition plate 30 is disposed in a sealed
space formed by the front cover 11, the stator body 12, and the
O-ring 71. Thus, both the pump chamber and the motor chamber can be
sealed by a single O-ring 71. Further, due to the simple
configuration of the space 13, support of the partition plate 30
and sealing by the O-ring 71 can be independent of each other.
[0041] As shown in FIG. 6, in this embodiment, the stator 50 has
six poles. More specifically, three of the stator coils 52 are
assigned with the U-phase, V-phase, and W-phase of the three-phase
current that is applied from a driving circuit (not shown). The
other three stator coils 62 are connected in series to the U-phase,
V-phase, and W-phase stator coils 62, respectively. The stator
coils 62 are arranged in the circumferential direction. The molded
part 53 of the stator body 12 integrally couples the stator core 51
with the stator coils 52, so as to maintain a positional
relationship between the stator core 51 and the stator coils 52.
The rotor 40 is rotatably disposed at a center of the
circumferentially arranged stator coils 52. The stator body 12
integrally includes spacers 12f for maintaining separation of the
stator core 51 and the outer pipe part 32. The spacers 12f are
uniformly circumferentially spaced and are disposed outside the
stator core 51 in the radial direction perpendicular to the axis of
the rotation shaft 41. Due to this configuration, circumferentially
spaced curved spaces 12g are formed between the stator core 51 and
the outer pipe part 32 such that the stator core 51 is exposed to
the curved spaces 12g.
[0042] As shown in FIG. 4, the flange part 30a of the partition
plate 30 is held between the flange part 11c of the front cover 11
and the flange part 12a of the stator body 12. The stator body 12
includes a projecting strip 12e protruding rearward from a rear
surface thereof. The rear side of the stator body 12 is provided
with a rear cover 81 that functions as a housing member. The rear
cover 81 is made of an electrically conductive material and has a
hollow shape having an opening part facing forward. The rear cover
81 includes a groove 81a at an edge of the opening part. The
projecting strip 12e of the stator body 12 is loosely fitted in the
groove 81e of the rear cover 81. The gap between the projecting
strip 12e and the groove 81e is filled with a seal member 72 formed
by injecting a liquid seal agent into the gap and then hardening
the agent. Here, the stator body 12 integrally includes a connector
91 having a substantial hollow rectangular column shape. The
connector 91 protrudes rearward at a rear portion of the stator
body 12 such that an interior space of the connector 91 extends
radially outward. The projecting strip 12e extends along an outer
surface of the connector 91 at a rearward position. The seal member
72 also seals a gap formed between the connector 91 and the rear
cover 81.
[0043] As shown in FIG. 3, four clamps 92 are attached to an outer
circumference of the purge pump 1. As shown in FIG. 4, the clamps
92 engage with a front surface of the flange part 11c of the front
cover 11 and a rear surface of a flange part 81b of the rear cover
81, so as to fixably secure the front cover 11 and the rear cover
81 to each other.
[0044] In an assembly process, the impeller 20 and the rotor 40 are
attached to the partition plate 30 by the rotation shaft 41 and the
bearings 42. They are then inserted into the front cover 11 from
the rear. Next, the stator body 12 and the rear cover 81 are
attached to the front cover 11 from the rear. The assembly of these
components of the purge pump 1 carried out in one direction, e.g.
in the forward direction, simplifies and eases the assembly
process, thereby offering the potential to enhance
productivity.
[0045] A circuit board 60 is fixed to the rear surface of the
stator body 12 and is covered by the rear cover 81. The circuit
board 60 has a plate shape extending in the radial direction and is
within the outer circumference of the outer pipe part 32 of the
partition plate 30 from a plan view along the axial direction. The
circuit board 60 includes circuit elements (not shown), such as an
integrated circuit (IC) chip, on a front or rear surface thereof
such that the circuit elements form an electric circuit of the
circuit board 60. The circuit board 60 is provided with coil
terminals 61, a power terminal 62, and a grounding terminal 63 that
extend forward from the circuit board 60 and penetrate the circuit
board 60 rearward to be connected with the electric circuit of the
circuit board 60. The circuit board 60 may be integrated with the
stator body 12.
[0046] The coil terminals 61 are electrically coupled to the stator
coils 52. The grounding terminal 63 contacts an inward surface of
the outer pipe part 32 of the partition plate 30 and is connected
with the rear cover 81. The grounding terminal 63 is also
electrically coupled to an external grounding terminal (not shown)
housed in the connector 91. The power terminal 62 supplies
electrical power to the electric circuit of the circuit board 60.
In this embodiment, the power terminal 62 extends from the circuit
board 60 and into the connector 91 and is configured to be
connected to an external power source to serve as a "connector
terminal." The connector 91 may be separated formed from the stator
body 12.
[0047] Because the circuit elements of the circuit board 60 are
rearward of the partition plate 30 and are positioned within the
radial periphery of the motor chamber defined by the outer pipe
part 32 of the partition plate 30, acoustic waves and vibrations
emitted forward from the circuit board 60 and the stator coils 52
can be absorbed by the partition plate 30. In addition, the rear
side of the circuit board 60 is covered with the rear cover 81, so
that acoustic waves and vibrations emitted rearward from the
circuit board 60 and the stator coils 52 can be absorbed by the
rear cover 81.
[0048] A second embodiment will be described. The second embodiment
corresponds to the first embodiment with some differences relating
to positions of the coil terminals 61. Thus, while some of the
differences will be described in greater detail below, similar
configurations will not be described in the interest of
conciseness.
[0049] As shown in FIG. 7, each coil terminal 61 of the second
embodiment extends forward from the circuit board 60 and penetrates
the stator body 12. The front portion of the coil terminals 61 are
each disposed in the curved spaces 12g formed radially outside the
stator core 51. The front end of each coil terminal 61 is connected
to the corresponding front side of the stator coil 52.
[0050] In the second embodiment, the stator coils 52 are connected
with the electric circuit of the circuit board 60 via the coil
terminals 61 disposed radially outside the stator coils 52. Each
coil terminal 61 is connected to the corresponding stator coil 52
via a side of the coil terminal 61 further from the circuit board
60. Accordingly, the coil terminals 61 are not disposed between the
stator coils 52 and the circuit board 60. Therefore, the circuit
board 60 can be disposed nearer the stator coils 52, reducing the
size of the purge pump 1 in the axial direction of the rotation
shaft 41.
[0051] Each coil terminal 61 is disposed radially outside the
stator 50 and partially overlaps the stator 50 in the radial
direction of the rotation shaft 41. For instance, a part of each
coil terminal 61 is in a space radially outside of the stator 50 in
the curved spaces 12g. Thus, the axial size of the purge pump 1 is
not increased by the coil terminals 61. In addition, it is not
necessary to provide additional spaces for the coil terminals 61,
so that an increase in the radial size of the purge pump 1 can be
avoided.
[0052] Further, the coil terminals 61 receive heat from the stator
coils 52 and radiate the heat toward the outer pipe part 32 of the
partition plate 30. Thus, the heat of the stator coils 52 is
radiated to the outside via the outer pipe part 32 of the partition
plate 30, thereby offering the potential to reduce thermal damage
to the stator 50.
[0053] A third embodiment will be described. The third embodiment
corresponds to the first embodiment with some differences. Thus,
while some of the differences will be described in greater detail
below, similar configurations will not be described in the interest
of conciseness. For instance, the purge pump 1 of the third
embodiment includes a rear cover 82 and a seal member 73, instead
of the rear cover 81 and the O-ring 71 of the first embodiment.
[0054] As shown in FIG. 8, the rear cover 82 includes a flange part
82b extending forward from a radially outer periphery of the rear
cover 82. The flange part 82b extends forward so as to be radially
outside the flange part 11c of the front cover 11, e.g., by
surrounding an outer circumference of the flange part 11c of the
front cover 11. The flange part 82b of the rear cover 82 may also
be positioned so as to overlap the flange part 12a of the stator
body 12. At least a majority of the portion of the coil terminal 61
is not overlapped by the outer pipe part 32 in the radial
direction.
[0055] The front cover 11 is coupled to the rear cover 82 by the
clamps 92 in a state where the flange part 12a of the stator body
12 is held between the front cover 11 and the rear cover 82.
However, it may be difficult to secure clamps 92 attached to a
position where the flange part 82b of the rear cover 82 is
positioned radially outside the flange part 11c of the front cover
11. So, the flange part 82b may have some cut portions, e.g.
notches, such that the clamps 92 can engage with the flange part
11c of the front cover 11 and can engage an outer periphery 82c of
a bottom portion of the rear cover 82 at the cut portions.
[0056] The flange part 12a of the stator body 12 includes a convex
portion protruding from a front surface thereof. The flange part
11c of the front cover 11 includes a concave portion recessed from
a rear surface thereof. The convex portion of the flange part 12a
is loosely fitted in the concave portion of the flange part 11c. A
gap between the concave portion of the flange part 11c and the
convex portion of the flange part 12a is filled with a seal member
73 formed by injecting a liquid sealing agent into the gap and then
hardening the agent. Similarly, the seal member 72 is provided
between the flange part 12a of the stator body 12 and the outer
periphery 82c of the bottom portion of the rear cover 82.
[0057] In accordance with the third embodiment, the rear opening of
the outer pipe part 32 of the partition plate 30 is covered with
the rear cover 82. That is, the outer pipe part 32 of the partition
plate 30 opens toward an interior space of the rear cover 82. Thus,
when acoustic waves and vibrations are emitted by the stator 50 and
leak from the rear opening of the outer pipe part 32, the rear
cover 82 can prevent leakage of the acoustic waves and vibrations
to the outside. Further, acoustic waves and vibrations emitted by
the coil terminals 61 in a direction perpendicular to the coil
terminals 61 can be absorbed by the flange part 82b of the rear
cover 82.
[0058] A fourth embodiment will be described. The fourth embodiment
corresponds to the first embodiment with some differences. Thus,
while some of the differences will be described in greater detail
below, similar configurations will not be described in the interest
of conciseness. For example, the elastic part 33 of the fourth
embodiment includes support parts 33a.
[0059] As shown in FIGS. 9 and 10, the elastic part 33 includes
four support parts 33a arranged circumferentially between the
bearing support part 31 and the outer pipe part 32. Each support
part 33a may be formed to be elastically deformable by cutting a
part of a front plate portion of the partition plate 30 and bending
the part toward the motor chamber. As shown in FIG. 9, a leading
edge 33b of each support part 33a contacts a front surface of the
stator body 12. As shown in FIGS. 10 and 11, each support part 33a
includes a guide surface 33c extending in a flow direction of a
fluid forced by the impeller 20 along the support part 33a of the
partition plate 30, which is shown by dashed arrows in FIGS. 10 and
11. Accordingly, the leading edges 33b are positioned on a
downstream side of the fluid flow. As a result of cutting and
bending the partition plate 30 to form the support parts 33a, the
partition plate 30 includes an opening 33d in front of the support
parts 33a.
[0060] As shown in FIGS. 10 and 11, each support part 33a actually
extends in a circumferential direction about the axis of the
rotation shaft 41 and bends rearward. In FIG. 9, solid arrows show
a flow of the fluid, e.g. air containing fuel vapor, which is
suctioned via the inlet port 11a and then is discharged from the
outlet port 11b by the impeller 20. Meanwhile, dashed arrows show a
flow of a part of the fluid, which flows into the motor chamber
through the openings 33d.
[0061] In accordance with the fourth embodiment, the leading edges
33b of the support parts 33a contact the front surface of the
molded body 53 of the stator body 12. So, the partition plate 30 is
biased forward due to the elastic force of the support parts 33a,
when the flange part 30a of the partition plate 30 is engaged with
the flange part 11c of the front cover 11. Thus, the partition
plate 30 can be positioned at a predetermined position with respect
to the stator 50. As a result, the impeller 20 supported by the
partition plate 30 via the bearings 42 and the rotation shaft 41
can be positioned at the predetermined position with respect to the
stator 50. In addition, when vibrations are transmitted from the
rotation shaft 41 to the support parts 33a, the support parts 33a
elastically deform so as to absorb the vibrational energy. Further,
because the fluid flows from the pump chamber into the motor
chamber through the openings 33d of the partition plate 30, the
partition plate 30 and components of the brushless motor 45 can be
cooled. For example, the fluid flow includes a first flow passing
radially outside the bearings 42 to a space between the rotor 40
and the stator body 12 and a second flow toward the curved spaces
12g. Thus, the bearings 42, the stator body 50 and the partition
plate 30 can be efficiently cooled.
[0062] The guide surface 33c of each support part 33a extends along
the direction of the fluid flow generated by the impeller 20. Thus,
the fluid flows smoothly along each guide surface 33c from the pump
chamber into the motor chamber through the openings 33d, so that
the motor can be efficiently cooled by the fluid. Further, the
partition plate 30 includes four support parts 33a and is supported
on the stator body 12 by the support parts 33a, each radially
positioned outside the bearings 42. Thus, the partition plate 30
can be stably supported on the stator body 12. To ensure the stable
support of the partition plate 30 on the stator body 12, the number
of the support parts 33a is preferably equal to or greater than
three.
[0063] A fifth embodiment will be described. The fifth embodiment
corresponds to the fourth embodiment with some differences. Thus,
while some of the differences will be described in greater detail
below, similar configurations will not be described in the interest
of conciseness. For example, in the fifth embodiment, one of the
bearings 42 is disposed frontward of the rotor 40, and the other is
disposed rearward of the rotor 40.
[0064] As shown in FIG. 12, the bearings 42 support the rotation
shaft 41 on both sides of the rotor 40. The rear-side bearing 42 is
directly affixed to the stator body 12. Thus, the rotation shaft 41
is supported so as to stabilize the position of the impeller 20. As
a result, vibration of the rotation shaft 41 can be suppressed,
thereby decreasing pulsations in the discharge pressure of the
purge pump 1.
[0065] A sixth embodiment will be described. The sixth embodiment
corresponds to the fourth embodiment with some differences. Thus,
while some of the differences will be described in greater detail
below, similar configurations will not be described in the interest
of conciseness. For example, the elastic part 33 of the sixth
embodiment includes support parts 33e, instead of the support parts
33a of the fourth embodiment.
[0066] As shown in FIGS. 13 and 14, the elastic part 33 includes
the support parts 33e near the outer pipe part 32. Each support
part 33e may have almost the same shape as each support part 33a of
the fourth embodiment. However, the leading edges 33f of the
support parts 33e contact corresponding front surfaces of the
spacers 12f Each support part 33e may actually be formed by cutting
a part of the partition plate 30 along an inner periphery of the
outer pipe part 32 and bending the part rearward. Thus, each
support part 33e extends in the circumferential direction about the
axis of the rotation shaft 41 and slopes rearward, similar to the
support parts 33a shown in FIGS. 10 and 11. The partition plate 30
includes openings 33g in front of the support parts 33e. Each
opening 33g is formed by cutting and bending rearward the
corresponding support part 33e.
[0067] In accordance with the sixth embodiment, the openings 33g
are disposed backward of the volute part 21 and located radially
outside the impeller 20. Thus, the fluid easily flows from the
volute part 21 into the motor chamber through the openings 33g, so
as to cool the components of the brushless motor 45 more
efficiently.
[0068] A seventh embodiment will be described. The seventh
embodiment corresponds to the fifth embodiment with some
differences. Thus, while some of the differences will be described
in greater detail below, similar configurations will not be
described in the interest of conciseness. For example, in the
seventh embodiment, the bearing support part 31 of the partition
plate 30 is configured to house the rotor 40 and the bearings 42
therein. The partition plate 30 is made from a nonmagnetic
material.
[0069] As shown in FIG. 15, the bearing support part 31 has a
hollow cylindrical shape with a closed rear end such that the
bearings 42 and the rotor 40 are housed therein. The bearing
support part 31 supports the outer circumferences of the bearings
42 and is disposed along an inner circumference of the stator 50.
Thus, the bearing support part 31 can transmit heat from the
bearings 42 and the stator 50 to the outer pipe part 32, thereby
radiating heat from the outer pipe part 32 toward the outside of
the purge pump 1.
[0070] The present teaching is not limited to the above-described
embodiments and can be modified in various ways while being within
the scope of the teaching. For example, the present teaching can be
applied to various pumps instead of the purge pump 1 installed on
the vehicle. Various motors can be used instead of the brushless
motor 45. For example, it is possible to use a motor including
stator coils that are circumferentially arranged and an annular
rotor disposed around the stator coils.
* * * * *