U.S. patent application number 16/087606 was filed with the patent office on 2019-04-04 for electric blower and electric vacuum cleaner equipped with same.
This patent application is currently assigned to MITSUBISHI ELECTRIC CORPORATION. The applicant listed for this patent is MITSUBISHI ELECTRIC CORPORATION, Mitsubishi Electric Home Appliance Co., Ltd.. Invention is credited to Mitsumasa Hamazaki, Mamoru Hayatsu, Masaya Teramoto.
Application Number | 20190101129 16/087606 |
Document ID | / |
Family ID | 59962813 |
Filed Date | 2019-04-04 |
![](/patent/app/20190101129/US20190101129A1-20190404-D00000.png)
![](/patent/app/20190101129/US20190101129A1-20190404-D00001.png)
![](/patent/app/20190101129/US20190101129A1-20190404-D00002.png)
![](/patent/app/20190101129/US20190101129A1-20190404-D00003.png)
![](/patent/app/20190101129/US20190101129A1-20190404-D00004.png)
![](/patent/app/20190101129/US20190101129A1-20190404-D00005.png)
![](/patent/app/20190101129/US20190101129A1-20190404-D00006.png)
![](/patent/app/20190101129/US20190101129A1-20190404-D00007.png)
United States Patent
Application |
20190101129 |
Kind Code |
A1 |
Teramoto; Masaya ; et
al. |
April 4, 2019 |
ELECTRIC BLOWER AND ELECTRIC VACUUM CLEANER EQUIPPED WITH SAME
Abstract
An electric blower includes: a rotor assembly; and a housing
accommodating the rotor assembly, and having an intake port and a
discharge port. The rotor assembly includes: a shaft; an impeller
mounted on the shaft, and generating a negative pressure at the
intake port by rotation; a rotor core mounted on the shaft; and a
pair of bearings having an inner peripheral side mounted on an
outer periphery of the shaft, and having an outer peripheral side
fixedly mounted on the housing. The pair of bearings are arranged
between the impeller and the rotor core. The housing includes a
frame formed of an integral body of a bearing holding portion and a
stator holding portion, the bearing holding portion holding the
pair of bearings in a state where outer peripheral surfaces of the
bearings are in contact with the bearing holding portion, and the
stator holding portion holding a stator which drives the rotor
core.
Inventors: |
Teramoto; Masaya;
(Fukaya-shi, Saitama, JP) ; Hayatsu; Mamoru;
(Fukaya-shi, Saitama, JP) ; Hamazaki; Mitsumasa;
(Fukaya-shi, Saitama, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
MITSUBISHI ELECTRIC CORPORATION
Mitsubishi Electric Home Appliance Co., Ltd. |
Chiyoda-ku, Tokyo
Fukaya-shi, Saitama |
|
JP
JP |
|
|
Assignee: |
MITSUBISHI ELECTRIC
CORPORATION
Chiyoda-ku, Tokyo
JP
Mitsubishi Electric Home Appliance Co., Ltd.
Fukaya-shi, Saitama
JP
|
Family ID: |
59962813 |
Appl. No.: |
16/087606 |
Filed: |
January 25, 2017 |
PCT Filed: |
January 25, 2017 |
PCT NO: |
PCT/JP2017/002560 |
371 Date: |
September 21, 2018 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F04D 29/58 20130101;
F04D 29/5806 20130101; H02K 9/06 20130101; F04C 2240/40 20130101;
F04D 29/584 20130101; F04D 25/082 20130101; F04D 29/056 20130101;
H02K 5/1735 20130101; F04D 29/059 20130101; F04D 25/0606 20130101;
F04D 29/624 20130101; A47L 9/0411 20130101; F04D 29/4253 20130101;
F04D 29/42 20130101; F04C 2240/50 20130101 |
International
Class: |
F04D 29/056 20060101
F04D029/056; F04D 29/42 20060101 F04D029/42; A47L 9/04 20060101
A47L009/04 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 29, 2016 |
JP |
2016-065729 |
Claims
1. An electric blower comprising: a rotor assembly; and a housing
accommodating the rotor assembly, and having an intake port and a
discharge port, wherein the rotor assembly includes: a shaft; an
impeller mounted on the shaft, and generating a negative pressure
at the intake port by rotation; a rotor core mounted on the shaft;
and a pair of bearings having an inner peripheral side mounted on
an outer periphery of the shaft, and having an outer peripheral
side fixedly mounted on the housing, the pair of bearings are
arranged between the impeller and the rotor core, the housing
includes a frame formed of an integral body of a bearing holding
portion and a stator holding portion, the bearing holding portion
holding the pair of bearings in a state where outer peripheral
surfaces of the bearings are in contact with the bearing holding
portion, and the stator holding portion holding a stator which
drives the rotor core, and the bearing holding portion projects in
an axial direction of the bearing holding portion toward the stator
holding portion side.
2. (canceled)
3. The electric blower according to claim 1, wherein the frame is
made of an aluminum alloy.
4. The electric blower according to claim 1, wherein the bearing is
fixed to the bearing holding portion by an adhesive agent having an
elastic modulus smaller than an elastic modulus of the bearing or
the bearing holding portion.
5. The electric blower according to claim 1, wherein the frame has
an air hole through which a flow of air generated due to the
driving of the impeller flows into the frame.
6. The electric blower according to claim 1, wherein the frame
includes a rib in a flow passage for the flow of air generated due
to the driving of the impeller.
7. An electric vacuum cleaner comprising the electric blower
described in claim 1.
Description
FIELD
[0001] The present invention relates to an electric blower.
BACKGROUND
[0002] In recent years there has been a demand for electric vacuum
cleaners to be smaller in size and weight. Accordingly, it is also
necessary to reduce the size of an electric blower incorporated
into an electric vacuum cleaner. In designing a miniaturized
electric blower, when the diameter of an impeller which generates a
negative pressure by, rotation is reduced, it becomes necessary to
cause the impeller to rotate at a higher speed so as to acquire a
greater air volume. When the impeller rotates at a higher speed, a
temperature of bearings increases along with a high-speed rotation
of the impeller leading to a deterioration of the lifespan of the
bearings. Particularly, in an electric blower which uses an
electric motor of a type which does not use a commutator and brush,
such as a DC brushless motor, as a power source, the hearing is a
part which is prone to malfunctioning first in many cases.
Accordingly, the lifespan of the bearing directly relates to the
lifespan of the electric'blower. As a method fix improving the
lifespan, means for dissipating heat generated Prow bearings using
a heat sink structure can be specified. A method is known which
adopts a structure where a heat sink assembly equipped with a
plurality of legs is fixed to a hearing assembly so as to dissipate
heat generated from the beatings (see PTL 1).
CITATION LIST
Patent Literature
[0003] [PTL 1] JP 2014-220998 A
SUMMARY
Technical Problem
[0004] However, in the above-mentioned prior art, a sleeve is
interposed between the heat sink assembly and the bearings. That
is, a structure is adopted where heat generated from the bearings
is not easily transferred to a heat sink directly. Further, a
surface area of the heat sink assembly is small and hence, a
sufficient heat dissipation effect cannot be acquired. Moreover,
the heat sink assembly is formed as a part separate from a frame
and hence, there is the problem that a large number of steps are
required in assembly thus towering ease of assembly.
[0005] The present invention has been made to overcome the
above-mentioned problems, and it is an object of the present
invention to provide an electric blower having a heat sink
structure with a high heat dissipation effect so as to allow
beatings to have the long lifespan.
Solution to Problem
[0006] An electric blower according to the present invention
includes: a rotor assembly; and a housing accommodating the rotor
assembly, and having an intake port and a discharge port. The rotor
assembly includes: a shaft; an impeller mounted on the shaft, and
generating a negative pressure at the intake port by rotation; a
rotor core mounted on the shaft; and a pair of bearings having an
inner peripheral side mounted on an outer periphery of the shaft,
and having an outer peripheral side fixedly mounted on the housing.
The pair of bearings are arranged between the impeller and the
rotor core. The housing includes a frame formed of an integral body
of a bearing holding portion and a stator holding portion, the
bearing holding portion holding the pair of bearings in a state
where outer peripheral surfaces of the hearings are in contact with
the bearing holding portion, and the stator holding portion holding
a stator which drives the rotor core.
Advantageous Effects of Invention
[0007] In the present invention, the housing includes the frame
formed of an integral body of the bearing holding portion and the
stator holding portion, the bearing holding portion holding the
bearings in a state where the outer peripheral surfaces of the
bearings are in contact with the bearing holding portion. According
to the present invention, it is possible to provide an electric
blower where heat generated from the bearings can be efficiently
dissipated.
BRIEF DESCRIPTION OF DRAWINGS
[0008] FIG. 1 is a perspective view showing an external appearance
of an electric blower according to an embodiment 1 of the present
invention as viewed from a frame side.
[0009] FIG. 2 is a longitudinal cross-sectional view of the
electric blower according to the embodiment 1 of the present
invention taken along a plane passing through the center of a
shaft.
[0010] FIG. 3 is an exploded perspective view of the electric
blower according to the embodiment 1 of the present invention.
[0011] FIG. 4 is a side view of a rotor assembly of the electric
blower according to the embodiment 1 of the present invention.
[0012] FIG. 5 is a longitudinal cross-sectional view of a frame
forming a portion of a housing of the electric blower according to
the embodiment 1 of the present invention.
[0013] FIG. 6 is a perspective view showing an external appearance
of a frame forming a portion of a housing of an electric blower
according to an embodiment 2 of the present invention as viewed
from a side where an impeller is disposed.
[0014] FIG. 7 is a side view of a frame forming a portion of a
housing of an electric blower according to an embodiment 3 of the
present invention as viewed from a side on which a rib is
formed.
DESCRIPTION OF EMBODIMENTS
Embodiment 1
[0015] Hereinafter, embodiments of the present invention are
described with reference to drawings.
[0016] FIG. 1 is a perspective view showing an external appearance
of an electric blower according to an embodiment I of the present
invention as viewed from a frame side.
[0017] FIG. 2 is a longitudinal cross-sectional view of the
electric blower according to the embodiment 1 of the present
invention taken along a plane passing through the center of a
shaft.
[0018] FIG. 3 is an exploded perspective view of the electric
blower according to the embodiment 1 of the present invention.
[0019] FIG. 4 is a side view of a rotor assembly of the electric
blower according to the embodiment 1 of the present invention.
[0020] FIG. 5 is a longitudinal cross-sectional view of a frame
forming a portion of a housing of the electric blower according to
the embodiment 1 of the present invention.
[0021] An electric blower I includes a rotor assembly 6 and a
housing 20. The housing 20 has an intake port 20a and a discharge
port 20b, and accommodates the rotor assembly 6 therein. The
housing 20 includes a fan cover 2 which covers an impeller 8
described later, a diffuser 3, a bracket 4, a frame 5 and a stator
7.
[0022] The rotor assembly 6 includes a shaft 11, the impeller 8, a
rotor core 10, and a pair of bearings 9. The impeller 8 is mounted
on the shaft 11, and generates a negative pressure at the intake
port 20a by rotation. The rotor core 10 is mounted on the shaft 11,
and applies a rotational force to the shaft 11 by the stator 7
described later. Inner peripheral surfaces of the pair of bearings
9 are mounted on an outer periphery of the shaft 11, and outer
peripheral surfaces of the pair of bearings 9 are fixedly mounted
on the housing 20 side. The pair of bearings 9 are arranged between
the impeller 8 and the mans core 10. A spring 12 is provided
between die pair of bearings 9, and the spring 12 applies a preload
to the bearings 9 in a direction that the bearings 9 separate from
each other.
[0023] The an cover 2 has the intake port 20a, and covers the
impeller 8. An outer periphery of the fan cover 2 and an outer
periphery of the bracket 4 are fixed with each other. The bracket 4
accommodates the diffuser 3 therein. The diffuser 3 is a
disk-shaped member, and a plurality of guide blades are disposed in
a fixed manner on the impeller 8 side of the diffuser 3. When the
impeller 8 rotates in a state where the impeller 8 is mounted on
the shaft 11, air is fed outward in the radial direction from the
impeller 8, and pressure recovery is performed on the air by an air
passage formed by the plurality of guide blades disposed on the
diffusor 3 and the fan cover 2. A gap is formed between an outer
edge of the diffuser 3 and an inner surface of an outer peripheral
portion of the bracket 4, and air is guided to the hack surface
side of the diffuser 3, that is, to the side where the stator 7 is
disposed through the gap.
[0024] The frame 5 forms a portion of the housing 20. The frame 5
has a cylindrical shape rotationally symmetrical about the shaft 11
and the cylindrical shape includes a stepped portion. On a paper on
which FIG. 5 is drawn, the right side end portion of the frame 5 is
open, in the frame 5, a cylindrical portion (first cylindrical
portion) having a smaller diameter forms a bearing holding portion
13 which holds the bearings 9 in a state where outer peripheral
surfaces of the bearings 9 are in contact with the bearing holding
portion 13. In the frame 5, a cylindrical portion (second
cylindrical portion) having a larger diameter thrills a stator
holding portion 14 which holds the stator 7. As described above,
the frame 5 is formed of an integral body of the bearing holding
portion 13 and the stator holding portion 14. An end portion of the
first cylindrical portion on the side which does not communicate
with the second cylindrical portion has a flange portion 13a which
comes into contact with an end portion of a bearing 9 in an axial
direction of the bearing 9. The center of the end portion is
open.
[0025] As shown in FIG. 3, a center portion of the diffuser 3 and a
renter portion of the bracket 4 are open, and the bearing holding
portion 13, which is the first cylindrical portion, is inserted
into the center portions of the diffuser 3 and the bracket 4.
[0026] In mounting the rotor assembly 6 into the housing 20, first,
the rotor assembly 6 in a state where the impeller 8 is not mounted
on the shaft 11 is inserted into the housing 20 through an open end
of the second cylindrical portion of the frame 5 from the bearing 9
side. At this stage of operation, the bearing 9 on the side
opposite to the rotor core 10 is fixedly mounted on the bearing
holding portion 13 in a state were an end portion of the bearing 9
in the axial direction is in contact with an inner surface of the
flange portion 13a of the first cylindrical portion of the frame 5,
Next, the stator 7 is inserted into the housing 20 through the open
end of the second cylindrical portion of the frame 5. The stator 7
is fixed to the stator holding portion 14 in a state where the
stator 7 faces the rotor core 10.
[0027] Next, the operation of the electric blower according to the
embodiment 1 of the present invention is described.
[0028] When electric power is supplied to the electric blower 1, a
rotational force applied to the rotor core 10 through the stator 7
so that the impeller 8 is rotationally driven about the shaft 11.
When the impeller 8 rotates, air in the vicinity of the impeller 8
is pushed outward in the radial direction. A negative pressure is
generated at the intake port 20a of the housing 20 such that the
air pushed outward is replenished from outside of the housing 20.
As indicated by a first airflow A in FIG. 2, flowing air sucked
into the electric blower 1 due to the driving of the impeller 8
passes through the diffuser 3 and the bracket 4 and, thereafter, is
discharged to the outside of the housing 20 from the discharge port
20b.
[0029] The pair of bearings 9 are held and fixed in a contact state
with the hearing holding portion 13 of the flame 5 forming a
portion of the housing 20. As a result, heat generated in the
bearings 9 due to the rotation of the rotor assembly 6 is directly
transferred to the frame 5. The heat is transferred to the frame 5
so that the frame 5 functions as a heat sink. The frame 5 ranging
from the bearing holding portion 13 to the stator holding portion
14 is formed of an integral component. Accordingly, the frame 5 has
a large surface area and hence, a high heat dissipation effect can
be acquired. A portion of the first airflow A discharged from the
discharge port 20b flows along an outer periphery of the frame 5
and hence, a heat dissipation effect of the frame 5 con be further
enhanced.
[0030] As a result, a temperature of the bearings 9 is prevented
from significantly increasing and hence, the lifespan of the
bearings 9 is extended. Particularly, in an electric blower which
uses an electric motor of a type which does not use a commutator
and brush, such as a DC brushless motor, as a power source, a
bearing is a part which is prone to malfunctioning first in many
cases. Accordingly, the above-mentioned configuration leads to the
extension of the lifespan of the electric blower as a whole.
Further, by causing the frame 5 per se to function as a heat sink,
it becomes unnecessary to provide parts having a heat dissipation
effect besides the frame 5 and hence, the number of parts is
reduced and it is possible to reduce the number of assembly steps.
Moreover, the bearing holding portion 13 and the stator holding
portion 14 are parts of the same component and hence, accuracy in
positioning of the bearing holding portion 13 and accuracy in
positioning of the stator holding portion 14 can be ensured by
ensuring only accuracy in positioning of the frame 5 alone.
Accordingly, a jig and bonding means become unnecessary at the time
of assembly and hence, ease of assembly is enhanced.
[0031] The bearings 9 are directly fixed to the bearing holding
portion 13 in a contact state with the bearing holding portion 13.
In the prior art, positions of outer peripheries of a pair of
bearings are aligned using a cylindrical sleeve which surrounds the
bearings. The sleeve is interposed between the bearings and a frame
and hence, heat is not easily transferred directly to the frame
from the bearings. In the electric blower 1 of the embodiment 1,
heat generated from the bearings 9 is directly transferred to the
frame 5 and hence, a heat dissipation effect is enhanced. Further,
a sleeve is not used so that the number of parts is reduced whereby
it is possible to reduce the number of assembly steps.
[0032] As shown in FIG. 5, in the frame 5, an end portion of the
bearing holding portion 13 on the stator holding portion 14 side
projects in an axial direction of the bearing holding portion 13
toward the stator holding portion 14 side. With such a
configuration, as shown in FIG. 2, a stator supporting portion 7a
of the stator 7 and the bearing 9 on the stator 7 side can be
disposed in an overlapping manner in the axial direction and hence,
a distance between the bearings 9 and the rotor core 10 can be
narrowed. A load in the radial direction is imposed on the bearings
9 with the rotation of the rotor assembly 6. The narrower the
distance between the bearings 9 and the rotor core 10, the smaller
the load becomes. Accordingly, such a configuration leads to the
extension of the lifespan of the bearings. Further, an axial length
of the rotor assembly 6 can be shortened and hence, it is possible
to reduce the size of the entire electric blower 1.
[0033] The frame 5 is desirably made of an aluminum alloy. An
aluminum alloy has high thermal conductivity so that heat generated
from the bearings 9 is easily transferred to the frame 5.
Accordingly, it is possible to expect that the frame 5 has a high
heat dissipation effect as a heat sink.
[0034] The bearings 9 may be fixed to the bearing holding portion
13 by an adhesive agent. For example, when the frame 5 is made of
an aluminum alloy, and the bearings 9 are made of a material other
than an aluminum alloy, a material for forming the frame 5 and a
material for forming the bearings 9 differ from each other in
coefficient of thermal expansion. When the bearings 9 generate heat
due to the rotation of the shaft 11, the frame 5 is also heated.
When the bearings 9 and the frame 5 thermally expand, due to the
difference in coefficient of thermal expansion, a gap may be formed
between the frame 5 and the bearings 9. In this situation, when the
bearings 9 are fixed to the bearing holding portion 13 by an
adhesive agent having an elastic modulus smaller than an elastic
modulus of the bearings 9 or the bearing holding portion 13,
bonding between the bearings 9 and the bearing holding portion 13
can be maintained. Accordingly, even when the bearings 9 and the
frame 5 thermally expand, it is possible to suppress the bearing 9
escaping from the bearing holding portion 13.
[0035] As described above, the electric blower of the embodiment 1
includes the rotor assembly, and the housing accommodating the
rotor assembly therein, and having the intake port and the
discharge port. The rotor assembly includes the shaft, the impeller
mounted on the shaft, and generating a negative pressure at the
intake port by rotation, the rotor core mounted on the shaft, and
the pair of bearings having the inner peripheral side thereof
mounted on the outer periphery of the shaft, and having the outer
peripheral side thereof fixedly mounted on the housing side. The
pair of bearings are arranged between the impeller and the rotor
core. The housing includes the frame formed of the integral body of
the bearing holding portion and the stator holding portion. The
bearing holding portion holds the pair of bearings in a state where
the outer peripheral surfaces of the bearings are in contact with
the bearing holding portion. The stator holding portion holds the
stator which drives the rotor core. With such a configuration,
according to the embodiment 1, it is possible to provide an
electric blower where heat generated from the bearings can be
efficiently dissipated from the frame.
[0036] Further, the end portion of the bearing holding portion
projects in the axial direction of the bearing holding portion
toward the stator holding portion side and hence, the stator
supporting portion and the bearing on the stator side can be
disposed in an overlapping manner in the axial. Accordingly, the
distance between the bearings and the motor core can be narrowed.
The load in the radial direction is imposed on the bearings with
the rotation of the rotor assembly. The narrower the distance
between the bearings and the rotor core, the smaller the load
becomes. Therefore, such a configuration leads to the extension of
the lifespan of the bearings. Further, the axial length of the
rotor assembly can be shortened and hence, it is possible to reduce
the size of the electric blower.
[0037] It may be possible to adopt a structure where the bearing
holding portion of the frame does not project toward the stator
holding portion side. With such the structure, the frame is allowed
to have a shape which can be formed by drawing processing.
Accordingly, production cost can be lowered.
[0038] Further, the frame is made of an aluminum alloy and hence,
heat generated from the bearings is easily transferred to the frame
whereby heat generated from the bearings can be efficiently
dissipated from the frame.
[0039] The bearings are fixed to the bearing holding portion by the
adhesive agent having the elastic modulus smaller than the elastic
modulus of the hearings or the bearing holding portion.
Accordingly, it is possible to suppress the bearing escaping from
the bearing holding portion.
Embodiment 2
[0040] FIG. 6 is a perspective view showing an external appearance
of a frame forming a portion of a housing of an electric blower
according to an embodiment 2 of the present invention as viewed
from a side where an impeller is disposed. The electric blower of
the embodiment 2 differs from the electric blower of the embodiment
1 with respect to a point that a surface of a frame 5 perpendicular
to a shaft 11 has air holes 15, wherein the surface connects a
hearing holding portion 13, which forms a first cylindrical
portion, and a stator holding portion, which forms a second
cylindrical portion, with each other.
[0041] As indicated by a first airflow A in FIG. 2, flowing air
sucked into the electric blower 1 due to the driving of an impeller
8 passes through a diffuser 3 and a bracket 4 and, thereafter, is
discharged to the outside of the frame 5. A portion of the first an
A which is discharged from a discharge port 20b flows along an
outer periphery of the frame 5 thus cooling the frame 5 from an
outer surface of the frame 5. By forming the air holes 15 in the
frame 5, as indicated by a second airflow B in FIG. 2, the airflow
flows also into the frame 5. The airflow which enters the frame 5
through the air holes 15 is discharged to the outside of the frame
5 through a gap (not shown in the drawing) formed on the leeward
side of a stator 7. As described above, the frame 5 is cooled from
both the outer surface and an inner surface so that the heat
dissipation effect of the frame 5 can be further enhanced.
[0042] As described above, in the electric blower of the embodiment
2, the frame has the air holes through which the flow of air
generated due to the driving of the impeller flows into the frame.
With such a configuration, the airflow which enters the frame
through the air holes cools the inner surface of the frame so that
heat generated from the bearings can be efficiently dissipated from
the frame.
Embodiment 3
[0043] FIG. 7 is a side view of a frame forming a portion of a
housing of an electric blower according to an embodiment 3 of the
present invention as viewed from a side on which a rib is formed.
The electric blower kit the embodiment 3 differs from the electric
blower of the embodiment 2 with respect to a point that a frame
includes the rib in a flow passage for a flow of air generated due
to the driving of an impeller.
[0044] As indicated by a first airflow A in FIG. 2, flowing air
sucked into the electric blower 1 due to the driving of an impeller
8 passes through a diffuser 3 and a bracket 4 and, thereafter, is
discharged to the outside of the frame 5. A portion of the first
airflow A which is discharged from a discharge port 20b flows along
an outer periphery of the frame 5 thus cooling the frame 5 from an
outer surface of the frame 5. By forming the air holes 15 in the
frame 5, as indicated by a second airflow B in FIG. 2, the airflow
flows also into the frame 5. The airflow which enters the frame 5
through the air holes 15 is discharged to the outside of the frame
5 through a gap (not shown in the drawing) formed on the leeward
side of a stator 7. As described above, the frame 5 is cooled from
both the outer surface and an inner surface so that the heat
dissipation effect of the frame 5 can be further enhanced.
[0045] As shown in FIG. 7, the frame 5 includes a rib 16 in the
flow passage for the flow of air generated due to the driving of
the impeller. The rib 16 is formed on a surface of the frame 5
described in the embodiment 2 which has the air holes 15. The rib
16 may have either of a shape which projects toward the bearing
holding portion 13 side from the surface in which the air holes 15
are formed or a shape which projects toward the stator holding
portion 14 side from the surface in which the air holes 15 are
formed. The rib 16 desirably has a flat shape having a wide
surface. With the formation of the rib 16, a surface area of the
frame 5 increases and hence, the heat dissipation effect is
enhanced.
[0046] Further, the flat rib 16 is desirably disposed along the
flow of the second airflow B. The rib 16 is formed on the surface
of the frame 5 which has the air holes 15 such that the rib 16
extends radially along the radial direction. The second airflow B
flows inward in the radial direction toward the shaft 11 from a gap
formed between an outer edge of the diffuser 3 and an inner surface
of an outer peripheral portion of the bracket 4. For example, when
the rib 16 has the shape which projects toward the bearing holding
portion 13 side from the surface in which the air holes 15 are
formed, the second airflow B flows along a side surface of the flat
rib 16 disposed radially along the radial direction. With such a
configuration, the second airflow B efficiently cools the rib 16.
Accordingly, a heat dissipation effect of the frame 5 can be
further enhanced. The efficient cooling of the rib 16 also leads to
the enhancement of the strength of the frame 5.
[0047] The flat rib 16 may be disposed such that the wide surface
of the rib 16 is orthogonal to a direction along which the second
airflow B flows. In this case, by forming the air holes 15 on the
windward side of the wide surface of the rib 16, the second airflow
B which impinges on the rib 16 flows along the wide surface. The
second airflow B is guided so as to flow toward the air holes 15.
The rib 16 may be formed such that a distal end of the rib 16 on
the bearing holding portion 13 side inclines toward the upstream
side in the second airflow B. The second airflow B is efficiently
guided so as to flow toward the air holes 15. As a result, the
second airflow B effectively flows into the frame 5 from the air
holes 15 so that the airflow cools the inner surface of the frame
whereby heat generated from the bearings can be efficiently
dissipated from the frame.
[0048] When the rib 16 has a shape which projects toward the stator
holding portion 14 side from the surface in which the air holes 15
are formed, the rib 16 may be disposed radially along the radial
direction. The rib 16 may be disposed such that the direction of
the rib 16 is rotated by 90 degrees so that a line perpendicular to
the wide surface of the flat rib 16 extends radially along the
radial direction. The second airflow B which enters the frame 5
from the air holes 15 flows along the wide surface of the rib 16
thus efficiently cooling the rib 16. Accordingly, a heat
dissipation effect of the frame 5 can be further enhanced.
[0049] As described above, the rib 16 is formed on the surface in
which the air holes 15 are formed. However, the air holes 15 may
not be formed in the surface. For example, in the frame 5 having no
air holes 15, the rib 16 may be formed on an outer side of the
stator holding portion 14. The rib 16 is formed in the flow passage
for the first airflow A so that the rib 16 is cooled whereby a heat
dissipation effect of the frame 5 can be enhanced.
[0050] As described above, in the electric blower if the embodiment
3, the frame includes the rib formed in the flow passage for the
flow of air generated due to the driving of the impeller.
Accordingly, an airflow generated due to the driving of the
impeller cools the rib. The frame on which the rib is formed is
cooled and hence, heat generated from the bearings can be
efficiently dissipated from the frame.
[0051] The electric blower which has been described in the
embodiment 1, the embodiment 2 or the embodiment 3, can be used as
a drive source of an electric vacuum cleaner, for example. The
lifespan of the electric blower directly relates to the product
lifespan of an electric vacuum cleaner. Accordingly, by loading an
electric blower with the extended lifespan into an electric vacuum
cleaner, it is possible to expect the acquisition of an
advantageous effect of extending the product lifespan of the
electric vacuum cleaner.
INDUSTRIAL APPLICABILITY
[0052] The electric blower according to the present invention is
utilized as an electric blower which uses an electric motor of a
type which does not use a commutator and brush, such as a DC
brushless motor, as a power source, for example. Further, the
electric blower according to the present invention is loaded into
an electric vacuum cleaner, for example.
REFERENCE SIGNS LIST
[0053] 1 electric blower
[0054] 2 fan cover
[0055] 3 diffuser
[0056] 4 bracket
[0057] 5 frame
[0058] 6 rotor assembly
[0059] 7 stator
[0060] 7a stator supporting portion
[0061] 8 impeller
[0062] 9 bearing
[0063] 10 rotor core
[0064] 11 shaft
[0065] 12 spring
[0066] 13 bearing holding portion.
[0067] 13a flange portion
[0068] 14 stator holding portion
[0069] 15 air hole
[0070] 16 rib
[0071] 20 housing
[0072] 20a intake port
[0073] 20b discharge port
[0074] A first airflow
[0075] B second airflow
* * * * *