U.S. patent application number 15/608270 was filed with the patent office on 2017-12-14 for blower apparatus.
This patent application is currently assigned to Nidec Corporation. The applicant listed for this patent is Nidec Corporation. Invention is credited to Yuko Hino, Akihiko Makita, Tomoyuki Tsukamoto, Seung-Sin Yoo.
Application Number | 20170356458 15/608270 |
Document ID | / |
Family ID | 60573704 |
Filed Date | 2017-12-14 |
United States Patent
Application |
20170356458 |
Kind Code |
A1 |
Hino; Yuko ; et al. |
December 14, 2017 |
BLOWER APPARATUS
Abstract
This blower apparatus includes an air blowing portion including
a plurality of flat plates arranged with an axial gap defined
between adjacent ones of the flat plates; a motor portion arranged
to rotate the air blowing portion; and a housing arranged to house
the air blowing portion and the motor portion. The flat plates
include an air hole arranged to pass therethrough in an axial
direction. Once the air blowing portion starts rotating, an air
flow traveling radially outward is generated between the flat,
plates by viscous drag of surfaces of the flat plates and a
centrifugal force. Thus, gas supplied through the air inlet and the
air hole travels radially outwardly of the air blowing portion.
Accordingly, a reduced thickness of the blower apparatus does not
result in a significant reduction in the air blowing
efficiency.
Inventors: |
Hino; Yuko; (Kyoto, JP)
; Yoo; Seung-Sin; (Kyoto, JP) ; Tsukamoto;
Tomoyuki; (Kyoto, JP) ; Makita; Akihiko;
(Kyoto, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Nidec Corporation |
Kyoto |
|
JP |
|
|
Assignee: |
Nidec Corporation
Kyoto
JP
|
Family ID: |
60573704 |
Appl. No.: |
15/608270 |
Filed: |
May 30, 2017 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
62347380 |
Jun 8, 2016 |
|
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F04D 25/06 20130101;
F04D 29/4246 20130101; F04B 17/00 20130101; F04D 29/083 20130101;
F04D 25/062 20130101; F04B 35/04 20130101; F04D 29/281 20130101;
F04D 17/161 20130101; F04D 29/626 20130101; F04D 25/0626 20130101;
F04D 29/162 20130101 |
International
Class: |
F04D 29/62 20060101
F04D029/62; F04D 29/08 20060101 F04D029/08; F04D 25/06 20060101
F04D025/06; F04B 35/04 20060101 F04B035/04 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 15, 2017 |
JP |
2017-049380 |
Claims
1. A blower apparatus comprising: an air blowing portion arranged
to rotate about a central axis extending in a vertical direction; a
motor portion arranged to rotate the air blowing portion; and a
housing arranged to house the air blowing portion and the motor
portion; wherein the housing includes: a lower plate portion
arranged to cover at least a portion of a lower side of the air
blowing portion, and support, the motor portion; an upper plate
portion arranged above the lower plate portion, and including an
air inlet arranged to pass therethrough in an axial direction; and
a side wall portion arranged to cover a lateral side of the air
blowing portion between the upper plate portion and the lower plate
portion, and including an air outlet arranged to face in a radial
direction at at least one circumferential position; the air blowing
portion includes a plurality of flat plates arranged in the axial
direction with an axial gap defined between adjacent ones of the
flat plates; at least one of the flat plates includes an air hole
arranged to pass therethrough in the axial direction; and each air
hole is arranged to be in communication with a space radially
outside of the air blowing portion through the axial gap.
2. The blower apparatus according to claim 1, wherein the flat
plates include a top flat plate arranged at a highest position of
all the flat plates, the top flat plate being arranged axially
below and radially inward of an inner edge portion of the upper
plate portion when viewed in the axial direction, the inner edge
portion defining the air inlet; and an axial distance between an
outer edge of the top flat plate and the inner edge portion is
arranged to be smaller than a radial distance between the outer
edge of the top flat plate and the inner edge portion,
3. The blower apparatus according to claim 1, wherein the flat
plates include a top flat plate arranged at a highest position of
all the flat plates, the top flat plate being arranged radially
inward of an inner edge portion of the upper plate portion when
viewed in the axial direction, the inner edge portion defining the
air inlet; and the top flat plate and the upper plate portion are
arranged to radially overlap at least in part with each other.
4. The blower apparatus according to claim 1, wherein at least one
of the flat plates includes an outer edge arranged below the upper
plate portion and radially outward of the air inlet; and an axial
distance between the upper plate portion and a highest one of the
at least one of the flat plates is arranged to be smaller than an
axial dimension of the axial gap.
5. The blower apparatus according to claim 1, wherein the flat
plates include a top flat plate arranged at a highest position of
all the flat plates, the top flat plate being arranged radially
inward of an inner edge portion of the upper plate portion when
viewed in the axial direction, the inner edge portion defining the
air inlet; at least one of the flat plates includes an outer edge
arranged below the upper plate portion and radially outward of the
inner edge portion; and a radial distance between an outer edge of
the top flat plate and the inner edge portion is arranged to be
smaller than an axial distance between the upper plate portion and
a highest one of the at least one of the flat plates.
6. The blower apparatus according to claim 1, wherein the flat
plates include a bottom flat plate arranged at a lowest position of
all the flat plates, the bottom flat plate including the air hole
arranged to pass therethrough in the axial direction.
7. The blower apparatus according to claim 1, wherein the flat
plates include a bottom flat plate arranged at a lowest position of
all the flat plates, the bottom flat plate including no air hole
arranged to pass therethrough in the axial direction.
8. The blower apparatus according to claim 1, wherein the flat
plates include a top flat plate arranged at a highest position of
all the flat plates, and a bottom flat plate arranged at a lowest
position of all the flat plates; and each of the top flat plate and
the bottom flat plate is arranged to have a thickness greater than
a thickness of each remaining flat plate.
9. The blower apparatus according to claim 1, wherein at least one
of the flat plates includes an outer end portion having a thickness
gradually decreasing in a radially outward direction.
10. The blower apparatus according to claim 1, further comprising
an elastic member arranged on a lower surface of the upper plate
portion, wherein the elastic member is arranged along an inner edge
portion of the upper plate portion, the inner edge portion defining
the air inlet.
11. The blower apparatus according to claim 1, wherein a center of
the air inlet is arranged to coincide with the central axis.
12. The blower apparatus according to claim 1, wherein the motor
portion includes: a stationary portion including an armature and a
bearing housing; and a rotating portion including a shaft, a
bearing member, and a magnet arranged radially opposite to the
armature; the bearing housing and a combination of the shaft and
the bearing member are arranged to have a lubricating fluid
therebetween; the bearing housing and the rotating portion are
arranged to together define a gap defining a seal portion
therebetween, the seal portion having a surface of the lubricating
fluid defined therein; and in the seal portion, a distance between
the bearing housing and the rotating portion is arranged to
increase with increasing distance from the surface of the
lubricating fluid.
13. The blower apparatus according to claim 1, wherein the motor
portion includes: a stationary portion including an armature; a
rotating portion including a magnet arranged radially opposite to
the armature; and a ball bearing arranged to connect the rotating
portion to the stationary portion such that the rotating portion is
rotatable with respect to the stationary portion.
14. The blower apparatus according to claim 1, wherein the side
wall portion includes a plurality of the air outlets at a plurality
of circumferential positions.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
[0001] The present invention relates to a blower apparatus.
2. Description of the Related Art
[0002] A centrifugal blower apparatus which generates an air flow
traveling radially outward by rotating an impeller including a
plurality of blades is known. A known blower apparatus including an
impeller is described in, for example, JP-A 2008-88985.
[0003] In the blower apparatus described in JP-A 2008-88985, a
plurality of blades referred to as fan blades push surrounding gas
to generate air flows traveling radially outward.
SUMMARY OF THE INVENTION
[0004] In recent years, there has still been a demand for
reductions in the size and thickness of electronic devices.
Accordingly, there has also been a demand for a reduction in the
thickness of blower apparatuses used to cool the interiors of the
electronic devices.
[0005] Here, in the case where an impeller is used to generate air
flows, as in the blower apparatus described in JP-A 2008-88985, air
flows pushed by a blade leak from axially upper and lower ends of
the blade while the impeller is rotating. As a result, air pressure
is lower at the axially upper and lower ends of the blade than in
the vicinity of an axial middle of the blade. Accordingly, a
reduction in the thickness of the blower apparatus, which involves
a reduction in the axial dimension of the impeller, will result in
a failure to secure sufficient air blowing efficiency.
[0006] An object of the present invention is to provide a technique
for realizing a centrifugal blower apparatus which is excellent in
air blowing efficiency.
[0007] A blower apparatus according to a preferred embodiment of
the present invention includes an air blowing portion arranged to
rotate about a central axis extending in a vertical direction; a
motor portion arranged to rotate the air blowing portion; and a
housing arranged to house the air blowing portion and the motor
portion. The housing includes a lower plate portion arranged to
cover at least a portion of a lower side of the air blowing
portion, and support the motor portion; an upper plate portion
arranged above the lower plate portion, and including an air inlet
arranged to pass therethrough in an axial direction; and a side
wall portion arranged to cover a lateral side of the air blowing
portion between the upper plate portion and the lower plate
portion, and including an air outlet arranged to face in a radial
direction at at least one circumferential position. The air blowing
portion includes a plurality of flat plates arranged in the axial
direction with an axial gap defined between adjacent ones of the
flat plates. At least one of the flat plates includes an air hole
arranged to pass therethrough in the axial direction. Each air hole
is arranged to be in communication with a space radially outside of
the air blowing portion through the axial gap.
[0008] According to the above preferred embodiment of the present
invention, once the air blowing portion starts rotating, an air
flow traveling radially outward is generated in the axial gap
between the adjacent ones of the flat plates by viscous drag of
surfaces of the flat plates and a centrifugal force. Thus, gas
supplied through the air inlet and the air hole travels radially
outwardly of the air blowing portion. Since the air flow is
generated between the flat plates, the air flow does not easily
leak upwardly or downwardly, and thus, an improvement in air
blowing efficiency is achieved. Accordingly, a reduced thickness of
the blower apparatus according to the above preferred embodiment of
the present invention does not result in a significant reduction in
the air blowing efficiency. In addition, the blower apparatus
according to the above preferred embodiment of the present
invention is superior to a comparable centrifugal fan including an
impeller in terms of being silent.
[0009] The above and other elements, features, steps,
characteristics and advantages of the present invention will become
more apparent from the following detailed description of the
preferred embodiments with reference to the attached drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] FIG. 1 is a perspective view of a blower apparatus according
to a first preferred embodiment of the present invention.
[0011] FIG. 2 is a top view of the blower apparatus according to
the first preferred embodiment.
[0012] FIG. 3 is a sectional view of the blower apparatus according
to the first, preferred embodiment.
[0013] FIG. 4 is an exploded perspective view of the blower
apparatus according to the first preferred embodiment.
[0014] FIG. 5 is a partial sectional view of the blower apparatus
according to the first preferred embodiment.
[0015] FIG. 6 is a partial sectional view of a blower apparatus
according to a modification of the first preferred embodiment.
[0016] FIG. 7 is a partial sectional view of a blower apparatus
according to a modification of the first preferred embodiment.
[0017] FIG. 8 is a partial sectional view of a blower apparatus
according to a modification of the first preferred embodiment.
[0018] FIG. 9 is a partial sectional view of a blower apparatus
according to a modification of the first preferred embodiment.
[0019] FIG. 10 is a partial sectional view of a blower apparatus
according to a modification of the first preferred embodiment.
[0020] FIG. 11 is a partial sectional view of a blower apparatus
according to a modification of the first preferred embodiment.
[0021] FIG. 12 is a partial sectional view of a blower apparatus
according to a modification of the first preferred embodiment.
[0022] FIG. 13 is a partial sectional view of a blower apparatus
according to a modification of the first preferred embodiment.
[0023] FIG. 14 is a partial sectional view of a blower apparatus
according to a modification of the first preferred embodiment.
[0024] FIG. 15 is a top view of a blower apparatus according to a
modification of the first preferred embodiment.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0025] Hereinafter, blower apparatuses according to preferred
embodiments of the present, invention will be described. It is
assumed herein that a side on which an upper plate portion is
arranged with respect to a lower plate portion is an upper side,
and the shape of each member or portion and relative positions of
different members or portions will be described based on the above
assumption. It should be noted, however, that the above definition
of the upper and lower sides is not meant, to restrict in any way
the orientation of a blower apparatus according to any preferred
embodiment of the present invention at the time of manufacture or
when in use.
1. First Preferred Embodiment
[0026] FIG. 1 is a perspective view of a blower apparatus 1
according to a first preferred embodiment of the present invention.
FIG. 2 is a top view of the blower apparatus 1. FIG. 3 is a
sectional view of the blower apparatus 1 taken along line A-A in
FIG. 2. FIG. 4 is an exploded perspective view of the blower
apparatus 1. FIG. 5 is a partial sectional view of the blower
apparatus 1. The blower apparatus 1 is a centrifugal blower
apparatus designed to generate an air flow traveling radially
outward by rotating an air blowing portion 40. The blower apparatus
1 is, for example, installed in an electronic device, such as, for
example, a personal computer, to cool an interior thereof. Note
that the blower apparatus 1 according to a preferred embodiment of
the present invention may alternatively be used for other
purposes.
[0027] Referring to FIGS. 1 to 4, the blower apparatus 1 includes a
housing 20, a motor portion 30, and the air blowing portion 40.
[0028] The housing 20 is a case arranged to house the motor portion
30 and the air blowing portion 40. The housing 20 includes a lower
plate portion 21, a side wall portion 22, and an upper plate
portion 23.
[0029] The lower plate portion 21 is arranged to define a bottom
portion of the housing 20. The lower plate portion 21 is arranged
to extend radially below the air blowing portion 40 to cover at
least a portion of a lower side of the air blowing portion 40. In
addition, the lower plate portion 21 is arranged to support the
motor portion 30.
[0030] The side wall portion 22 is arranged to extend upward from
the lower plate portion 21. The side wall portion 22 is arranged to
cover a lateral side of the air blowing portion 40 between the
lower plate portion 21 and the upper plate portion 23. In addition,
the side wall portion 22 includes an air outlet 201 arranged to
face in a radial direction at one circumferential position. In the
present preferred embodiment, the lower plate portion 21 and the
side wall portion 22 are defined integrally with each other. Note
that, the lower plate portion 21 and the side wall portion 22 may
alternatively be defined by separate members.
[0031] The upper plate portion 23 is arranged to define a cover
portion of the housing 20. The upper plate portion 23 is arranged
to extend radially above the lower plate portion 21. In addition,
the upper plate portion 23 includes an air inlet 202 arranged to
pass therethrough in an axial direction. In other words, the upper
plate portion 23 includes an inner edge portion 231 arranged to
define the air inlet 202. The air inlet 202 is, for example,
circular and is centered on a central axis 9 in a plan view.
[0032] The motor portion 30 is a driving portion arranged to rotate
the air blowing portion 40. Referring to FIG. 5, the motor portion
30 includes a stationary portion 31 and a rotating portion 32. The
stationary portion 31 is fixed to the lower plate portion 21, The
stationary portion 31 is thus arranged to be stationary relative to
the housing 20. The rotating portion 32 is supported to be
rotatable about the central axis 9 with respect to the stationary
portion 31.
[0033] The stationary portion 31 includes a stator fixing portion
311, a stator 312, and a bearing housing 313.
[0034] The stator fixing portion 311 is fitted in a fixing hole 211
defined in the lower plate portion 21. As a result, the stator
fixing portion 311 is fixed to the lower plate portion 21. The
stator fixing portion 311 is arranged to extend upward from the
fixing hole 211 to assume a cylindrical shape with the central axis
9 as a center thereof. The stator 312 is fixed to an outer
circumferential portion of an upper portion of the stator fixing
portion 311.
[0035] The stator 312 is an armature arranged to generate magnetic
flux in accordance with electric drive currents supplied from an
external source. The stator 312 is arranged to annularly surround
the central axis 9, which extends in a vertical direction. The
stator 312 includes, for example, an annular stator core defined by
laminated steel sheets, and conducting wires wound around the
stator core.
[0036] The bearing housing 313 is a member being cylindrical and
having a closed bottom. Specifically, the bearing housing 313
includes a disk-shaped bottom portion, and a cylindrical portion
arranged to extend upward from the bottom portion. The bearing
housing 313 is fixed to an inner circumferential surface of the
stator fixing portion 311.
[0037] The rotating portion 32 includes a shaft 321, a hub 322, a
bearing member 323, and a magnet 324.
[0038] The shaft 321 is a member arranged to extend along the
central axis 9. The shaft 321 according to the present preferred
embodiment includes a columnar portion arranged inside of a first
cylindrical portion 512, which will be described below, and
arranged to extend with the central axis 9 as a center thereof, and
a disk-shaped portion arranged to extend radially from a lower end
portion of the columnar portion.
[0039] The hub 322 is fixed to the shaft 321. The hub 322 is made
up of a hub body member 51 and a flange member 52.
[0040] The hub body member 51 includes a first top plate portion
511, the first cylindrical portion 512, a second cylindrical
portion 513, and a magnet holding portion 514.
[0041] The first top plate portion 511 is a disk-shaped portion
arranged to extend radially with the central axis 9 as a center
thereof. The first top plate portion 511 is arranged above the
stator 312. The first top plate portion 511 has a recessed portion
515 recessed from an upper surface thereof at an outer edge portion
thereof.
[0042] The first cylindrical portion 512 is arranged to extend
downward from the first top plate portion 511 to assume a
cylindrical shape with the central axis 9 as a center thereof. The
columnar portion of the shaft 321 is housed in the first
cylindrical portion 512. In addition, the shaft 321 is fixed to the
first cylindrical portion 512.
[0043] The second cylindrical portion 513 is arranged to extend
downward from the first top plate portion 511 to assume a
cylindrical shape with the central axis 9 as a center thereof. The
second cylindrical portion 513 is arranged to have an inside
diameter greater than an outside diameter of the first cylindrical
portion 512. In other words, the second cylindrical portion 513 is
arranged radially outside of the first cylindrical portion 512.
[0044] The magnet holding portion 514 is arranged to extend
downward from a radially outer end of the first top plate portion
511 to assume a cylindrical shape with the central axis 9 as a
center thereof. The magnet holding portion 514 is arranged radially
outside of the stator 312. The magnet 324 is fixed to an inner
circumferential surface of the magnet holding portion 514.
[0045] The flange member 52 includes an outer wall portion 521, a
second top plate portion 522, and a flat plate holding portion
523.
[0046] The outer wall portion 521 is a cylindrical portion arranged
to extend in the vertical direction with the central axis 9 as a
center thereof. The outer wall portion 521 is arranged to extend
along an outer circumferential surface of the magnet holding
portion 514 of the hub body member 51.
[0047] The second top plate portion 522 is arranged to extend
radially inward from an upper end portion of the outer wall portion
521 to assume the shape of a circular ring. The second top plate
portion 522 is arranged in the recessed portion 515, which is
defined in the upper surface of the first top plate portion 511 of
the hub body member 51. In addition, the upper surface of the first
top plate portion 511 and an upper surface of the second top plate
portion 522 are arranged at the same axial position.
[0048] The flat plate holding portion 523 is arranged to extend
radially outward from a lower end portion of the outer wall portion
521. The flat plate holding portion 523 is arranged to hold the air
blowing portion 40 on a radially outer side of the magnet holding
portion 514 of the hub body member 51. In the present preferred
embodiment, the air blowing portion 40 is mounted on an upper
surface of the flat plate holding portion 523. The flat, plate
holding portion 523 is thus arranged to hold a plurality of flat
plates 410 included in the air blowing portion 40.
[0049] The bearing member 323 is a cylindrical member arranged to
extend in the vertical direction with the central axis 9 as a
center thereof. The bearing member 323 is arranged to extend along
an outer circumferential surface of the first cylindrical portion
512 of the hub body member 51. In addition, the bearing member 323
is fixed to the outer circumferential surface of the first
cylindrical portion 512. The cylindrical portion of the bearing
housing 313 is arranged radially outside of the bearing member 323
and radially inside of the second cylindrical portion 513 of the
hub body member 51.
[0050] The magnet 324 is fixed to the inner circumferential surface
of the magnet holding portion 514 of the hub body member 51. In
addition, the magnet 324 is arranged radially outside of the stator
312. The magnet 324 according to the present preferred embodiment
is in the shape of a circular ring. A radially inner surface of the
magnet 324 is arranged radially opposite to the stator 312 with a
slight gap therebetween. In addition, an inner circumferential
surface of the magnet 324 includes north and south poles arranged
to alternate with each other in a circumferential direction. Note
that a plurality of magnets may be used in place of the magnet 324
in the shape of a circular ring. In the case where the plurality of
magnets are used, the magnets are arranged in the circumferential
direction such that north and south poles of the magnets alternate
with each other.
[0051] As illustrated in an enlarged view in FIG. 5, a lubricating
fluid 300 is arranged between the bearing housing 313 and a
combination of the shaft 321, the bearing member 323, and the hub
body member 51. A polyolester oil or a diester oil, for example, is
used as the lubricating fluid 300. The shaft 321, the hub 322, and
the bearing member 323 are supported to be rotatable with respect,
to the bearing housing 313 through the lubricating fluid 300. Thus,
in the present preferred embodiment, the bearing housing 313, which
is a component of the stationary portion 31, the combination of the
shaft 321, the bearing member 323, and the hub body member 51, each
of which is a component of the rotating portion 32, and the
lubricating fluid 300 together define a fluid dynamic bearing.
[0052] A surface of the lubricating fluid 300 is defined in a seal
portion 301, which is a gap between an outer circumferential
surface of the bearing housing 313 and an inner circumferential
surface of the second cylindrical portion 513 of the hub body
member 51. In the seal portion 301, the distance between the outer
circumferential surface of the bearing housing 313 and the inner
circumferential surface of the second cylindrical portion 513 is
arranged to increase with decreasing height. In other words, in the
seal portion 301, the distance between the outer circumferential
surface of the bearing housing 313 and the inner circumferential
surface of the second cylindrical portion 513 is arranged to
increase with increasing distance from the surface of the
lubricating fluid 300. Since the radial width of the seal portion
301 thus increases with decreasing height, the lubricating fluid
300 is attracted upward in the vicinity of the surface of the
lubricating fluid 300. This reduces the likelihood that the
lubricating fluid 300 will leak out of the seal portion 301.
[0053] Use of the fluid dynamic bearing as a bearing mechanism that
connects the stationary portion 31 and the rotating portion 32
allows the rotating portion 32 to rotate stably. Thus, the
likelihood of an occurrence of an unusual sound from the motor
portion 30 can be reduced.
[0054] Once electric drive currents are supplied to the stator 312
in the motor portion 30 as described above, magnetic flux is
generated around the stator 312. Then, interaction between the
magnetic flux of the stator 312 and magnetic flux of the magnet 324
produces a circumferential torque between the stationary portion 31
and the rotating portion 32, so that the rotating portion 32 is
caused to rotate about the central axis 9 with respect to the
stationary portion 31. The air blowing portion 40, which is held by
the flat plate holding portion 523 of the rotating portion 32, is
caused to rotate about the central axis 9 together with the
rotating portion 32.
[0055] Referring to FIGS. 4 and 5, the air blowing portion 40
includes the plurality of flat plates 410 and a plurality of
spacers 420. The flat plates 410 and the spacers 420 are arranged
to alternate with each other in the axial direction. In addition,
adjacent ones of the flat plates 410 and the spacers 420 are fixed
to each other through, for example, adhesion.
[0056] Referring to FIGS, 4 and 5, in the present preferred
embodiment, the flat plates 410 include a top flat plate 411, which
is arranged at the highest position, a bottom flat plate 412, which
is arranged at the lowest position, and four intermediate flat
plates 413, which are arranged below the top flat plate 411 and
above the bottom flat plate 412. That is, the number of flat plates
410 included in the air blowing portion 40 according to the present
preferred embodiment is six. The flat plates 410 are arranged in
the axial direction with an axial gap 400 defined between adjacent
ones of the flat plates 410.
[0057] Each flat plate 410 is made of, for example, a metal
material, such as stainless steel, or a resin material. Each flat
plate 410 may alternatively be made of, for example, paper. In this
case, paper including a glass fiber, a metal wire, or the like in
addition to plant fibers may be used. The flat plate 410 is able to
achieve higher dimensional accuracy when the flat plate 410 is made
of a metal material than when the flat plate 410 is made of a resin
material.
[0058] In the present preferred embodiment, each of the top flat
plate 411 and the four intermediate flat plates 413 is arranged to
have the same shape and size. Referring to FIGS. 1, 2, and 5, each
of the top flat plate 411 and the intermediate flat plates 413
includes an inner annular portion 61, an outer annular portion 62,
a plurality of ribs 63, and a plurality of air holes 60. In the
present preferred embodiment, the number of ribs 63 and the number
of air holes 60 included in each of the top flat plate 411 and the
intermediate flat plates 413 are both five.
[0059] The inner annular portion 61 is an annular portion centered
on the central axis 9. The inner annular portion 61 has a central
hole 65 (see FIG. 4) arranged to pass therethrough in the vertical
direction in a center thereof. The outer annular portion 62 is an
annular portion arranged radially outside of the inner annular
portion 61 with the central axis 9 as a center thereof. Each rib 63
is arranged to join the inner annular portion 61 and the outer
annular portion 62 to each other. Each air hole 60 is arranged to
be in communication with a space radially outside of the air
blowing portion 40 through the axial gap(s) 400 adjacent to the
flat plate 410 including the air hole 60 on the upper and/or lower
sides of the flat plate 410. Each air hole 60 is arranged at a
position overlapping with the air inlet 202 of the housing 20 when
viewed in the axial direction.
[0060] The bottom flat plate 412 is an annular and plate-shaped
member centered on the central axis 9. The bottom flat plate 412
has a central hole 65 arranged to pass therethrough in the vertical
direction in a center thereof.
[0061] Referring to FIG. 4, each spacer 420 is a member in the
shape of a circular ring. The spacers 420 are arranged between the
flat plates 410 to secure the axial gaps 400 between the flat
plates 410. Each spacer 420 has a central hole 429 arranged to pass
therethrough in the vertical direction in a center thereof. The
motor portion 30 is arranged in the central holes 65 of the flat
plates 410 and the central holes 429 of the spacers 420.
[0062] Each spacer 420 is arranged at a position axially coinciding
with the inner annular portion 61 of each of the top flat plate 411
and the intermediate flat plates 413. Thus, the spacer 420 is
arranged in a region in the
[0063] corresponding axial gap 400, the region covering only a
portion of the radial extent of the corresponding axial gap
400.
[0064] Once the motor portion 30 is driven, the air blowing portion
40 is caused to rotate together with the rotating portion 32. As a
result, viscous drag of a surface of each flat plate 410 and a
centrifugal force together generate an air flow traveling radially
outward in the vicinity of the surface of the flat plate 410. Thus,
an air flow traveling radially outward is generated in each of the
axial gaps 400 between the flat plates 410. Thus, gas above the
housing 20 is supplied to each axial gap 400 through the air inlet
202 of the housing 20 and the air holes 60 of the top flat plate
411 and the intermediate flat plates 413, and is discharged out of
the blower apparatus 1 through the air outlet 201, which is defined
in a side portion of the housing 20.
[0065] Here, each flat plate 410 is arranged to have an axial
thickness of about 0.1 mm. Meanwhile, each axial gap 400 is
arranged to have an axial dimension of about 0.3 mm. The axial
dimension of the axial gap 400 is preferably in the range of 0.2 mm
to 0.5 mm. An excessively large axial dimension of the axial gap
400 would lead to a separation between an air flow generated by a
lower surface of the flat plate 410 on the upper side and an air
flow generated by an upper surface of the flat plate 410 on the
lower side during rotation of the air blowing portion 40. This
separation could result in a failure to generate sufficient static
pressure in the axial gap 400 to discharge a sufficient volume of
air. Moreover, an excessively large axial dimension of the axial
gap 400 would make it difficult to reduce the axial dimension of
the blower apparatus 1. Accordingly, in this blower apparatus 1,
the axial dimension of the axial gap 400 is arranged to be in the
range of 0.2 mm to 0.5 mm. This arrangement allows the blower
apparatus 1 to achieve a reduced thickness while allowing an
increase in the static pressure in the axial gap 400 to discharge a
sufficient volume of air.
[0066] Each of the top flat plate 411 and the intermediate flat
plates 413 includes the air holes 60. Accordingly, in each of the
top flat plate 411 and the intermediate flat plates 413, the outer
annular portion 62, which is arranged radially outside of the air
holes 60, defines an air blowing region which generates an air flow
in the vicinity of a surface thereof. Meanwhile, the bottom flat
plate 412 includes no air hole 60. Therefore, in an upper surface
of the bottom flat plate 412, an entire region radially outside of
a portion of the bottom flat plate 412 which makes contact with the
spacer 420 defines an air blowing region. In other words, in the
upper surface of the bottom flat plate 412, a region which axially
coincides with the air holes 60 and the ribs 63 of the top flat
plate 411 and the intermediate flat plates 413, and a region which
axially coincides with the outer annular portions 62 thereof,
together define the air blowing region. In addition, in a lower
surface of the bottom flat plate 412, an entire region radially
outside of a portion of the bottom flat plate 412 which makes
contact with the flat plate holding portion 523 defines an air
blowing region. Notice that an air flow is generated by a lower
surface of the flat plate holding portion 523 as well.
[0067] As described above, the bottom flat plate 412 has air
blowing regions wider than the air blowing regions of the top flat
plate 411 and the intermediate flat plates 413. Therefore, the
axial gap 400 between the lowest one of the intermediate flat
plates 413 and the bottom flat plate 412 is able to have higher
static pressure than any other axial gap 400.
[0068] Air flows passing downward through the air inlet 202 and the
air holes 60 are drawn radially outward in each axial gap 400.
Therefore, the air flows passing through the air holes 60 become
weaker as they travel downward. In the present preferred
embodiment, the bottom flat plate 412 is arranged to have an air
blowing region wider than the air blowing regions of the top flat
plate 411 and the intermediate flat plates 413 to cause a stronger
air flow to be generated in the lowest one of the axial gaps 400
than in any other axial gap 400 to cause the air flows passing
downward through the air holes 60 to be drawn toward the lowest
axial gap 400. Thus, a sufficient volume of gas is supplied to the
lowest axial gap 400 as well. As a result, the air blowing portion
40 achieves improved air blowing efficiency.
[0069] In a related-art blower apparatus that generates air flows
by rotating an impeller including a plurality of blades, air flows
generated by the impeller leak at upper and lower end portions of
the impeller. This leakage of the air flows occurs regardless of
the axial dimension of the blower apparatus. Therefore, as the
blower apparatus is designed to be thinner, an effect of this
leakage on the blower apparatus as a whole becomes greater,
resulting in lower air blowing efficiency. Meanwhile, in the blower
apparatus 1 according to the present preferred embodiment, the air
flows are generated in the vicinity of the surfaces of the flat
plates 410, and therefore, the air flows do not easily leak upward
or downward. Therefore, even when the axial dimension of the air
blowing portion 40, which generates the air flows, is reduced, a
reduction in air blowing efficiency due to leakages of the air
flows does not easily occur. That is, even when the blower
apparatus 1 has a reduced thickness, a reduction in air blowing
efficiency thereof does not easily occur.
[0070] In addition, in a blower apparatus including an impeller,
periodic noise occurs owing to the shape, number, arrangement, and
so on of blades. However, this blower apparatus 1 is superior to a
comparable blower apparatus including an impeller in terms of being
silent, because the air flows are generated by the viscous drag of
the surface of each flat plate 410 and the centrifugal force in the
blower apparatus 1.
[0071] In addition, from the viewpoint of P-Q characteristics
(i.e., flow rate-static pressure characteristics), the blower
apparatus 1 including the flat plates 410 is able to produce a
higher static pressure in a low flow rate region than the blower
apparatus including the impeller. Therefore, when compared to the
blower apparatus including the impeller, the blower apparatus 1 is
suitable for use in a densely packed case, from which only a
relatively small volume of air can be discharged. Examples of such
cases include cases of electronic devices, such as, for example,
personal computers.
[0072] In the present preferred embodiment, the top flat plate 411
and all the intermediate flat plates 413 include the air holes 60.
Accordingly, all the axial gaps 400 are in axial communication with
a space above the housing 20 through the air inlet 202 and the air
holes 60.
[0073] Referring to FIG. 2, the air inlet 202 is centered on the
central axis 9. That is, a center of the air inlet 202 coincides
with the central axis 9. Meanwhile, the air blowing portion 40 is
also centered on the central axis 9. Accordingly, differences in
pressure do not easily occur at different circumferential positions
in the air blowing portion 40. This contributes to reducing noise.
It is assumed that, the term "coincide" as used here includes not
only "completely coincide" but also "substantially coincide".
[0074] Referring to FIG. 5, the top flat plate 411 is arranged
axially below and radially inward of the inner edge portion 231 of
the upper plate portion 23 when viewed in the axial direction, the
inner edge portion 231 defining the air inlet 202. In addition, an
axial distance D1 between an outer edge of the top flat plate 411
and the inner edge portion 231 of the upper plate portion 23 is
arranged to be smaller than a radial distance D2 between the outer
edge of the top flat, plate 411 and the inner edge portion 231 of
the upper plate portion 23.
[0075] A pressure generated by the rotation of the air blowing
portion 40 spreads only a certain distance from a surface of the
top flat plate 411. Therefore, a large axial distance between the
top flat plate 411 and the inner edge portion 231, which defines
the air inlet 202, would result in an easy occurrence of a
backflow. In the present preferred embodiment, the axial distance
D1 between the top flat plate 411 and the inner edge portion 231 is
arranged to be smaller than the radial distance D2 to reduce the
likelihood of an occurrence of a backflow phenomenon.
2. Example Modifications
[0076] While a preferred embodiment of the present invention has
been described above, it is to be understood that the present
invention is not limited to the above-described preferred
embodiment.
[0077] FIG. 6 is a partial sectional view of a blower apparatus 1A
according to a modification of the above-described preferred
embodiment. In the blower apparatus 1A according to the
modification illustrated in FIG. 6, an air blowing portion 40A
includes a plurality of flat plates 410A, similarly to the air
blowing portion 40 according to the above-described preferred
embodiment. The flat plates 410A include a top flat plate 411A,
which is arranged at the highest position. In addition, an upper
plate portion 23A of a housing 20A includes an air inlet 202A
arranged to pass therethrough in the vertical direction.
[0078] In this blower apparatus 1A, the top flat plate 411A is
arranged radially inward of an inner edge portion 231A of the upper
plate portion 23A when viewed in the axial direction, the inner
edge portion 231A defining the air inlet 202A. In addition, the top
flat plate 411A and the upper plate portion 23A are arranged to
radially overlap in part with each other. The blower apparatus 1A
is able to achieve a further reduced thickness since the upper
plate portion 23A and the top flat plate 411A are arranged to
radially overlap with each other as described above.
[0079] FIG. 7 is a partial sectional view of a blower apparatus 1B
according to another modification of the above-described preferred
embodiment. In the blower apparatus 1B according to the
modification illustrated in FIG. 7, an air blowing portion 40B
includes a plurality of flat plates 410B. The flat plates 410B are
arranged in the axial direction with an axial gap 400B defined
between adjacent ones of the flat plates 410B. The flat plates 410B
include a top flat plate 411B, which is arranged at the highest
position, and a bottom flat plate 412B, which is arranged at the
lowest position. Four of the flat plates 410B are arranged between
the top flat plate 411B and the bottom flat plate 412B, and the
highest one of the four flat plates 410B is referred to as a first
intermediate flat plate 414B, and the remaining three flat plates
410B are each referred to as a second intermediate flat plate 415B.
In addition, an upper plate portion 23B of a housing 20B includes
an air inlet 202B arranged to pass therethrough in the vertical
direction.
[0080] In this blower apparatus 1B, an outer edge of the top flat
plate 411B is arranged radially inward of an inner edge portion
231B of the upper plate portion 23B when viewed in the axial
direction, the inner edge portion 231B defining the air inlet 202B.
In addition, the top flat plate 411B and the upper plate portion
23B are arranged to radially overlap at least in part with each
other. Further, an outer edge of each of the bottom flat plate
412B, the first intermediate flat plate 414B, and the three second
intermediate flat plates 415B is arranged below the upper plate
portion 23B and radially outward of the air inlet 202B. That is, at
least one of the flat plates 410B includes an outer edge arranged
below the upper plate portion 23B and radially outward of the air
inlet 202B. Here, an axial distance D3 between the upper plate
portion 23B and the first intermediate flat plate 414B, which is
the highest one of the bottom flat plate 412B, the first
intermediate flat plate 414B, and the three second intermediate
flat plates 415B, is arranged to be smaller than an axial dimension
D4 of the axial gap 400B.
[0081] A pressure generated by rotation of the air blowing portion
40B spreads only a certain distance from a surface of each flat
plate 410B. Therefore, a large distance between the upper plate
portion 23B and the first intermediate flat plate 414B, which is
the closest to the upper plate portion 23B of all the flat plates
410B that are arranged to axially overlap with the upper plate
portion 23B, might produce a region in which the pressure generated
by the rotation of the air blowing portion 40B does not act between
the first intermediate flat plate 414B and the upper plate portion
23B. In the modification illustrated in FIG. 7, the distance D3
between the upper plate portion 23B and the first intermediate flat
plate 414B, which is the closest to the upper plate portion 23B, is
arranged to be small enough to achieve an improvement in static
pressure between the first intermediate flat plate 414B and the
upper plate portion 23B. This in turn leads to an increase in the
volume of air to be discharged from the blower apparatus 1B.
[0082] FIG. 8 is a partial sectional view of a blower apparatus 1C
according to yet another modification of the above-described
preferred embodiment. In the blower apparatus 1C according to the
modification illustrated in FIG. 8, an air blowing portion 40C
includes a plurality of flat plates 410C. The flat plates 410C
include a top flat plate 411C, which is arranged at the highest
position, a bottom flat plate 412C, which is arranged at the lowest
position, and four flat plates 410C arranged between the top flat
plate 411C and the bottom flat plate 412C. The four flat plates
410C arranged between the top flat plate 411C and the bottom flat
plate 412C will be hereinafter referred to as, from highest to
lowest, a first intermediate flat plate 414C, a second intermediate
flat plate 415C, a third intermediate flat plate 416C, and a fourth
intermediate flat plate 417C. In addition, an upper plate portion
23C of a housing 20C includes an air inlet 202C arranged to pass
therethrough in the vertical direction.
[0083] In this blower apparatus 1C, an outer edge of each of the
top flat plate 411C and the first intermediate flat plate 414C is
arranged radially inward of an inner edge portion 231C of the upper
plate portion 23C when viewed in the axial direction, the inner
edge portion 231C defining the air inlet 202C. Therefore, a large
radial distance D5 between the outer edge of the top flat plate
411C and the inner edge portion 231C might permit a backflow
phenomenon to occur in a gap between the outer edge of the top flat
plate 411C and the inner edge portion 231C.
[0084] An outer edge of each of the second intermediate flat plate
415C, the third intermediate flat plate 416C, the fourth
intermediate flat plate 417C, and the bottom flat plate 412C is
arranged below the upper plate portion 23C and radially outward of
the air inlet 202C. That is, at least, one of the flat, plates 410C
includes an outer edge arranged below the upper plate portion 23C
and radially outward of the air inlet 202C. Here, the axial
distance between the upper plate portion 23C and the second
intermediate flat plate 415C, which is arranged at the highest
position of these four flat plates 410C, will be referred to as an
axial distance D6.
[0085] In the modification illustrated in FIG. 8, the radial
distance D5 between the outer edge of the top flat plate 411C and
the inner edge portion 231C is arranged to be smaller than the
axial distance D6 between the second intermediate flat plate 415C
and the upper plate portion 23C. This contributes to preventing a
backflow phenomenon from occurring in the gap between the outer
edge of the top flat plate 411C and the inner edge portion 231C.
This in turn leads to improved air blowing efficiency.
[0086] FIG. 9 is a partial sectional view of a blower apparatus 1D
according to yet another modification of the above-described
preferred embodiment. In the blower apparatus 1D according to the
modification illustrated in FIG. 9, an air blowing portion 40D
includes a plurality of flat plates 410D. The flat plates 410D
include a top flat plate 411D, which is arranged at the highest
position, a bottom flat plate 412D, which is arranged at the lowest
position, and four intermediate flat plates 413D, which are
arranged between the top flat plate 411D and the bottom flat plate
412D.
[0087] In this blower apparatus 1D, all of the flat plates 410D,
including the bottom flat plate 412D, include air holes 60D
arranged to pass therethrough in the axial direction. The air holes
60D defined in the bottom flat plate 4120 allow gas supplied into a
housing 20D through an air inlet 202D to be supplied to a space on
the lower side of the bottom flat plate 412D. This leads to an
increase in the volume of air to be discharged from the blower
apparatus 1D,
[0088] FIG. 10 is a partial sectional view of a blower apparatus 1E
according to yet another modification of the above-described
preferred embodiment. In the blower apparatus 1E according to the
modification illustrated in FIG. 10, an air blowing portion 40E
includes a plurality of flat plates 410E. The flat plates 410E
include a top flat plate 411E, which is arranged at the highest
position, a bottom flat plate 412E, which is arranged at the lowest
position, and four flat plates 410E arranged between the top flat
plate 411E and the bottom flat plate 412E. The four flat plates
410E arranged between the top flat plate 411E and the bottom flat
plate 412E will be hereinafter referred to as, from highest to
lowest, a first intermediate flat plate 414E, a second intermediate
flat plate 415E, a third intermediate flat plate 416E, and a fourth
intermediate flat plate 417E.
[0089] In this blower apparatus 1E, an upper plate portion 23E of a
housing 20E includes a first air inlet 202E arranged to pass
therethrough in the vertical direction. A lower plate portion 21E
of the housing 20E includes a second air inlet 203E arranged to
pass therethrough in the vertical direction. In addition, each of
the top flat plate 411E, the first intermediate flat plate 414E,
the second intermediate flat plate 415E, the fourth intermediate
flat plate 417E, and the bottom flat plate 412E includes air holes
60E. Meanwhile, the third intermediate flat plate 416E includes no
air hole 60E.
[0090] Thus, gas supplied into the housing 20E through the first
air inlet 202E travels downward through the air holes 60E of the
top flat plate 411E, the first intermediate flat plate 414E, and
the second intermediate flat plate 415E toward an upper surface of
the third intermediate flat plate 416E. Gas is thus supplied to
three axial gaps 400E arranged above the third intermediate flat
plate 416E. Meanwhile, gas supplied into the housing 20E through
the second air inlet 203E travels upward through the air holes 60E
of the bottom flat plate 412E and the fourth intermediate flat
plate 417E toward a lower surface of the third intermediate flat
plate 416E. Gas is thus supplied to two axial gaps 400E arranged
below the third intermediate flat plate 416E.
[0091] As described above, in this blower apparatus 1E, gas is
supplied from both the upper and lower sides of the air blowing
portion 40E. Therefore, even if the number of flat plates 410E is
increased, a sufficient volume of gas can be supplied to each axial
gap 400E. Accordingly, the blower apparatus 1E is able to achieve
improved air blowing efficiency.
[0092] In addition, in this blower apparatus 1E, the third
intermediate flat plate 416E, which is arranged near the middle of
the plurality of flat plates 410E, includes no air hole 60E. This
prevents the gas supplied from the upper side and the gas supplied
from the lower side from colliding against each other to cause a
turbulent flow. This contributes to preventing an increase in
noise.
[0093] FIG. 11 is a partial sectional view of a blower apparatus 1F
according to yet another modification of the above-described
preferred embodiment. In the blower apparatus 1F according to the
modification illustrated in FIG. 11, an air blowing portion 40F
includes a plurality of flat plates 410F. The flat plates 410F
include a top flat plate 411F, which is arranged at the highest
position, a bottom flat plate 412F, which is arranged at the lowest
position, and four intermediate flat plates 413F, which are
arranged between the top flat plate 411F and the bottom flat plate
412F.
[0094] In this blower apparatus 1F, each of the top flat plate 411F
and the bottom flat plate 412F is arranged to have an axial
thickness greater than an axial thickness of each of the
intermediate flat plates 413F. Thus, the top flat plate 411F and
the bottom flat plate 412F are less easily deformed than the other
flat plates 410F.
[0095] On both the upper and lower sides of each intermediate flat
plate 413F, other ones of the flat plates 410F are arranged.
Therefore, an upper surface of each intermediate flat plate 413F
receives a pressure of an air flow generated by a lower surface of
the flat plate 410F arranged on the upper side. Meanwhile, a lower
surface of each intermediate flat plate 413F receives a pressure of
an air flow generated by an upper surface of the flat plate 410F
arranged on the lower side. Thus, both the upper and lower surfaces
of each intermediate flat plate 413F receive the pressures from
adjacent ones of the flat plates 410F. This allows each
intermediate flat plate 413F to stably rotate.
[0096] Meanwhile, a lower surface of the top flat plate 411F
receives a pressure from an adjacent one of the flat plates 410F,
while an upper surface of the top flat plate 411F receives little
pressure. In addition, an upper surface of the bottom flat plate
412F receives a pressure from an adjacent one of the flat plates
410F, while a lower surface of the bottom flat plate 412F receives
little pressure. Therefore, both the top flat plate 411F and the
bottom flat plate 412F tend to more easily wobble up and down than
the intermediate flat plates 413F.
[0097] In this blower apparatus 1F, the axial thickness of each of
the top flat plate 411F and the bottom flat plate 412F is made
greater than the axial thickness of any other flat plate 410F to
reduce the likelihood of a deformation of each of the top flat
plate 411F and the bottom flat plate 412F. This reduces the
likelihood that each of the top flat plate 411F and the bottom flat
plate 412F will be brought into contact with another member, such
as, for example, an adjacent one of the flat plates 410F or a
housing 20F.
[0098] FIG. 12 is a partial sectional view of a blower apparatus 1G
according to yet another modification of the above-described
preferred embodiment. In the blower apparatus 1G according to the
modification illustrated in FIG. 12, an air blowing portion 40G
includes a plurality of flat plates 410G. Each of the flat plates
410G includes an outer end portion having a thickness gradually
decreasing in a radially outward direction.
[0099] If each flat plate 410G had a uniform axial thickness even
at the outer end portion thereof, the outer end portion of the flat
plate 410G would have a cylindrical outer end surface. In this
case, a junction of the outer end surface with an upper surface of
the flat plate 410G, and a junction of the outer end surface with a
lower surface of the flat plate 410G, would both be angular.
Accordingly, an eddy might occur in an air flow around each
junction. Such an eddy in the air flow might result in reduced air
blowing efficiency and in noise.
[0100] In this blower apparatus 1G, the outer end portion of each
flat plate 410G is arranged to have a thickness gradually
decreasing in the radially outward direction to reduce the
likelihood of an occurrence of an eddy in an air flow. This leads
to improved air blowing efficiency and reduced noise.
[0101] FIG. 13 is a partial sectional view of a blower apparatus 1H
according to yet another modification of the above-described
preferred embodiment. In the blower apparatus 1H according to the
modification illustrated in FIG. 13, an air blowing portion 40H
includes a plurality of flat plates 410H. In addition, an upper
plate portion 23H of a housing 20H includes an air inlet 202H
arranged to pass therethrough in the vertical direction. In other
words, the upper plate portion 23H includes an inner edge portion
231H arranged to define the air inlet 202H.
[0102] In this blower apparatus 1H, an elastic member 24H is
arranged on a lower surface of the upper plate portion 23H. The
elastic member 24H is arranged along the inner edge portion 231H to
surround the inner edge portion 231H. In addition, an outer edge of
each flat plate 410H is arranged radially outward of the air inlet
202H. Thus, the outer edge of each flat plate 410H is arranged at a
position axially overlapping with the upper plate portion 23H.
Since the elastic member 24H is arranged around the inner edge
portion 231H, even if any flat plate 410H bends significantly, the
flat plate 410H will not make direct contact with the upper plate
portion 23H, making contact with the elastic member 24H instead.
This contributes to preventing each of the flat plates 410H and the
upper plate portion 23H from being damaged.
[0103] FIG. 14 is a partial sectional view of a blower apparatus 1J
according to yet another modification of the above-described
preferred embodiment. In the blower apparatus 1J according to the
modification illustrated in FIG. 14, a motor portion 30J includes a
stationary portion 31J, a rotating portion 32J, and two ball
bearings 33J.
[0104] The stationary portion 31J includes a stator fixing portion
311J and a stator 312J. The stator fixing portion 311J is a member
being cylindrical and having a closed bottom and fixed to a housing
20J. The stator 312J is an armature fixed to an outer
circumferential surface of the stator fixing portion 311J.
[0105] The rotating portion 32J includes a shaft 321J, a hub 322J,
and a magnet 324J. At least a lower end portion of the shaft 321J
is arranged inside of the stator fixing portion 311J. In addition,
an upper end portion of the shaft 321J is fixed to the hub 322J.
The magnet 324J is fixed to the hub 322J. The magnet 324J is
arranged radially opposite to the stator 312J.
[0106] Each ball bearing 33J is arranged to connect the rotating
portion 32J to the stationary portion 31J such that the rotating
portion 32J is rotatable with respect to the stationary portion
31J. Specifically, an outer race of each ball bearing 33J is fixed
to an inner circumferential surface of the stator fixing portion
311J of the stationary portion 31J. In addition, an inner race of
each ball bearing 33J is fixed to an outer circumferential surface
of the shaft 321J of the rotating portion 32J. Further, a plurality
of balls, each of which is a spherical rolling element, are
arranged between the outer race and the inner race. As described
above, instead of a fluid dynamic bearing, rolling-element
bearings, such as, for example, ball bearings, may be used as a
bearing structure of the motor portion 30J.
[0107] In the modification illustrated in FIG. 14, the motor
portion 30J includes the two ball bearings 33J. The ball bearings
33J are arranged near an upper end and a lower end of an axial
range over which the inner circumferential surface of the stator
fixing portion 311J and the shaft 321J are opposed to each other.
This contributes to preventing the shaft 321J from being inclined
with respect to a central axis 9J.
[0108] FIG. 15 is a top view of a blower apparatus 1K according to
yet another modification of the above-described preferred
embodiment. In the blower apparatus 1K according to the
modification illustrated in FIG. 15, a housing 20K includes a
plurality of air outlets 201K. Specifically, a side wall portion
22K includes the air outlets 201K, each of which is arranged to
face in a radial direction, at a plurality of circumferential
positions. The housing 20K includes tongue portions 203K, each of
which is arranged near a separate one of the air outlets 201K. In
addition, an air blowing portion 40K includes a plurality of flat
plates 410K arranged in the axial direction with an axial gap
defined between adjacent ones of the flat plates 410K.
[0109] In a centrifugal fan including an impeller, periodic noise
occurs owing to the shape, number, arrangement, and so on of
blades. In addition, such noise tends to easily occur around a
tongue portion. Accordingly, when air is to be discharged in a
plurality of directions, a deterioration in noise characteristics
occurs because of an increased number of tongue portions. However,
in this blower apparatus 1K, air flows traveling radially outward
are generated by rotation of the flat plates 410K, and therefore,
the blower apparatus 1K is able to achieve reduced periodic noise
when compared to the centrifugal fan including the impeller.
Therefore, the blower apparatus 1K, which is designed to discharge
air in a plurality of directions, does not significantly
deteriorate in noise characteristics doe to the tongue portions
203K.
[0110] Note that, although the number of flat plates included in
the air blowing portion is six in each of the above-described
preferred embodiment and the modifications thereof, this is not
essential to the present invention. The number of flat plates may
alternatively be two, three, four, five, or more than six.
[0111] Also note that, although the hub is defined by two members,
i.e., the hub body member and the flange member, in each of the
above-described preferred embodiment and the modifications thereof,
this is not essential to the present invention. The hub may
alternatively be defined by a single member, or three or more
members.
[0112] Also note that the detailed shape of any member may be
different from the shape thereof as illustrated in the accompanying
drawings of the present application. For example, the shape of any
of the housing, the air blowing portion, and the motor portion may
be different from that according to each of the above-described
preferred embodiment and the modifications thereof. Also note that
features of the above-described preferred embodiment and the
modifications thereof may be combined appropriately as long as no
conflict arises.
[0113] Preferred embodiments of the present invention are
applicable to blower apparatuses.
[0114] While preferred embodiments of the present invention have
been described above, it is to be understood that variations and
modifications will be apparent to those skilled in the art without
departing from the scope and spirit of the present invention. The
scope of the present invention, therefore, is to be determined
solely by the following claims.
* * * * *