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United States Patent Application 20170356462
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; a motor portion; and a housing. The housing includes an air inlet and an air outlet. Each of a top flat plate and intermediate flat plates among the flat plates includes an air hole and an air blowing region radially outside of the air hole. 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. A radial middle of the air blowing region of at least one of the intermediate flat plates is arranged radially outward of a radial middle of the air blowing region of an upwardly adjacent one of the flat plates.


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: 1000002678880
Appl. No.: 15/608482
Filed: May 30, 2017


Related U.S. Patent Documents

Application NumberFiling DatePatent Number
62347380Jun 8, 2016

Current U.S. Class: 1/1
Current CPC Class: F04D 29/626 20130101; F04B 35/04 20130101; F04B 17/00 20130101; F04D 29/083 20130101; F04D 25/06 20130101
International Class: F04D 29/62 20060101 F04D029/62; F04B 35/04 20060101 F04B035/04; F04D 29/08 20060101 F04D029/08; F04D 25/06 20060101 F04D025/06

Foreign Application Data

DateCodeApplication Number
Mar 15, 2017JP2017-049385

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: an air inlet arranged above the air blowing portion, and arranged to pass through a portion of the housing in an axial direction; and an air outlet arranged to face in a radial direction at at least one circumferential position radially outside of the air blowing portion; 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; the flat plates include: a top flat plate arranged at a highest position of all the flat plates; a bottom flat plate arranged at a lowest position of all the flat plates; and a plurality of intermediate flat plates arranged between the top flat plate and the bottom flat plate; each of the top flat plate and the intermediate flat plates includes: an air hole arranged to pass therethrough in the axial direction; and an air blowing region being a region radially outside of the air hole; a distance between the central axis and a radial middle position of the air blowing region of the intermediate flat plate that is arranged at a lowest position of all the intermediate flat plates is arranged to be greater than a distance between the central axis and a radial middle position of the air blowing region of the top flat, plate; and a distance between the central axis and a radial middle position of the air blowing region of each of the intermediate flat plates is arranged to be equal to or greater than a distance between the central axis and a radial middle position of the air blowing region of an upwardly adjacent one of the flat plates.

2. The blower apparatus according to claim 1, wherein the bottom flat plate is arranged to have an outside diameter greater than an outside diameter of the top flat plate; and each of the flat plates is arranged to have an outside diameter equal to or greater than an outside diameter of an upwardly adjacent one of the flat plates.

3. The blower apparatus according to claim 2, wherein each of the flat plates is arranged to have an outside diameter greater than the outside diameter of the upwardly adjacent one of the flat plates.

4. The blower apparatus according to claim 2, wherein each of the flat plates includes an outer end surface angled radially outward with decreasing height.

5. The blower apparatus according to claim 1, wherein a distance between the central axis and a radially outer end of the air hole that is arranged at a lowest position of all the air holes is arranged to be greater than a distance between the central axis and a radially outer end of the air hole that is arranged at a highest position of all the air holes; and a distance between the central axis and a radially outer end of each of the air holes is arranged to be equal to or greater than a distance between the central axis and the radially outer end of an upwardly adjacent one of the air holes.

6. The blower apparatus according to claim 5, wherein the distance between the central axis and the radially outer end of each of the air holes is arranged to be greater than the distance between the central axis and the radially outer end of the upwardly adjacent one of the air holes.

7. The blower apparatus according to claim 5, wherein each of the top flat plate and the intermediate flat plates includes an end surface defining an outer edge of the air hole, the end surface being angled radially outward with decreasing height.

8. The blower apparatus according to claim 1, wherein the air inlet is centered on the central axis.

9. 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.

10. 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.

11. The blower apparatus according to claim 1, wherein the housing 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 an air inlet arranged above the air blowing portion, and arranged to pass through a portion of the housing in an axial direction; and an air outlet arranged to face in a radial direction at at least one circumferential position radially outside of the air blowing portion. 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. The flat plates include a top flat plate arranged at a highest position of all the flat plates; a bottom flat plate arranged at a lowest position of all the flat plates; and a plurality of intermediate flat plates arranged between the top flat plate and the bottom flat plate. Each of the top flat plate and the intermediate flat plates includes an air hole arranged to pass therethrough in the axial direction, and an air blowing region being a region radially outside of the air hole. A distance between the central axis and a radial middle position of the air blowing region of the intermediate flat plate that is arranged at a lowest position of all the intermediate flat plates is arranged to be greater than a distance between the central axis and a radial middle position of the air blowing region of the top flat plate. A distance between the central axis and a radial middle position of the air blowing region of each of the intermediate flat plates is arranged to be equal to or greater than a distance between the central axis and a radial middle position of the air blowing region of an upwardly adjacent one of the flat plates.

[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 holes 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, since the radial middle position of the air blowing region is shifted radially outward from the top flat plate to the intermediate flat plate that is arranged at the lowest position, an improvement in air intake efficiency is achieved. This leads to a further improvement 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 top view of a blower apparatus according to a modification of the first preferred embodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] 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

[0022] 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 blower apparatuses according to preferred embodiments of the present invention may be used for other purposes.

[0023] Referring to FIGS. 1 to 4, the blower apparatus 1 includes a housing 20, a motor portion 30, and the air blowing portion 40.

[0024] 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.

[0025] 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.

[0026] 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. Mote that the lower plate portion 21 and the side wall portion 22 may alternatively be defined by separate members.

[0027] 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.

[0028] 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.

[0029] The stationary portion 31 includes a stator fixing portion 311, a stator 312, and a bearing housing 313.

[0030] 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.

[0031] 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.

[0032] 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.

[0033] The rotating portion 32 includes a shaft 321, a hub 322, a bearing member 323, and a magnet 324.

[0034] 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.

[0035] 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.

[0036] The hub body member 51 includes a first fop plate portion 511, the first cylindrical portion 512, a second cylindrical portion 513, and a magnet holding portion 514.

[0037] 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.

[0038] 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.

[0039] 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.

[0040] 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.

[0041] The flange member 52 includes an outer wall portion 521, a second top plate portion 522, and a flat plate holding portion 523.

[0042] 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.

[0043] 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.

[0044] 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.

[0045] 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.

[0046] 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.

[0047] 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.

[0048] 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.

[0049] 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.

[0050] 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.

[0051] 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.

[0052] 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, 414, 415, and 416, which are arranged below the top flat plate 411 and above the bottom flat plate 412. Here, the four intermediate flat plates 413 to 416 will be referred to as, from highest to lowest, a first intermediate flat plate 413, a second intermediate flat plate 414, a third intermediate flat plate 415, and a fourth intermediate flat plate 416. 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.

[0053] 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.

[0054] Referring to FIGS. 1, 2, and 5, each of the top flat plate 411 and the intermediate flat plates 413 to 416 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 to 416 are both five.

[0055] 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.

[0056] 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.

[0057] 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.

[0058] 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 to 416. Thus, the spacer 420 is arranged in a region in the corresponding axial gap 4 00, the region covering only a portion of the radial extent of the corresponding axial gap 400.

[0059] 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 to 416. Thus, a sufficient volume of gas is supplied to each axial gap 400, and the gas is discharged out of the blower apparatus 1 through the air outlet 201, which is defined in a side portion of the housing 20.

[0060] 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.

[0061] Each of the top flat plate 411 and the intermediate flat plates 413 to 416 includes the air holes 60 and an air blowing region which is a region radially outside of the air holes 60. In each of the top flat plate 411 and the intermediate flat plates 413 to 416, the outer annular portion 62, which is arranged radially outside of the air holes 60, defines the air blowing region, which generates an air flow in the vicinity of a surface thereof. In FIG. 5, a radial middle position of the air blowing region of each of the top flat plate 411 and the intermediate flat plates 413 to 416 is indicated by an inverted black triangle. Hereinafter, the radial middle position of the air blowing region of the top flat plate 411 will be referred to as a top middle position P1, the radial middle position of the air blowing region of the first intermediate flat plate 413 will be referred to as a first middle position P2, the radial middle position of the air blowing region of the second intermediate flat plate 414 will be referred to as a second middle position P3, the radial middle position of the air blowing region of the third intermediate flat plate 415 will be referred to as a third middle position P4, and the radial middle position of the air blowing region of the fourth intermediate flat plate 416 will be referred to as a fourth middle position P5.

[0062] 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 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.

[0063] In this blower apparatus 1, the bottom flat plate 412 is arranged to have an outside diameter greater than an outside diameter of the top flat plate 411. In addition, each of the flat plates 410 is arranged to have an outside diameter greater than an outside diameter of an upwardly adjacent one of the flat plates 410. Specifically, the first intermediate flat plate 413 is arranged to have an outside diameter greater than the outside diameter of the top flat plate 411, which is upwardly adjacent to the first intermediate flat plate 413. The second intermediate flat plate 414 is arranged to have an outside diameter greater than the outside diameter of the first intermediate flat plate 413, which is upwardly adjacent to the second intermediate flat plate 414. The third intermediate flat plate 415 is arranged to have an outside diameter greater than the outside diameter of the second intermediate flat plate 414, which is upwardly adjacent to the third intermediate flat plate 415. The fourth intermediate flat plate 416 is arranged to have an outside diameter greater than the outside diameter of the third intermediate flat plate 415, which is upwardly adjacent to the fourth intermediate flat plate 416. The bottom flat plate 412 is arranged to have an outside diameter greater than the outside diameter of the fourth intermediate flat plate 416, which is upwardly adjacent to the bottom flat plate 412.

[0064] In this blower apparatus 1, a radially inner end of the outer annular portion 62, which defines the air blowing region, of each of the top flat plate 411 and the intermediate flat plates 413 to 416 is arranged at the same radial position. Therefore, the radial middle position of the air blowing region of each of the intermediate flat plates 413 to 416 is arranged radially outward of the radial middle position of the air blowing region of an upwardly adjacent one of the flat plates 410. Specifically, the first middle position P2 of the first intermediate flat plate 413 is arranged radially outward of the top middle position P1 of the top flat plate 411. The second middle position P3 of the second intermediate flat plate 414 is arranged radially outward of the first middle position P2 of the first intermediate flat plate 413. The third middle position P4 of the third intermediate flat plate 415 is arranged radially outward of the second middle position P3 of the second intermediate flat plate 414. The fourth middle position P5 of the fourth intermediate flat plate 416 is arranged radially outward of the third middle position P4 of the third intermediate flat plate 415.

[0065] Thus, a distance between the central axis 9 and the fourth middle position P5 of the fourth intermediate flat plate 416, which is arranged at the lowest position of ail the intermediate flat plates 413 to 416, is greater than a distance between the central axis 9 and the top middle position P1 of the top flat plate 411. In addition, a distance between the central axis 9 and the radial middle position of the air blowing region of each of the intermediate flat plates 413 to 416 is greater than a distance between the central axis 9 and the radial middle position of the air blowing region of an upwardly adjacent one of the flat plates 410.

[0066] Specifically, the distance between the central axis 9 and the first middle position P2 of the first intermediate flat plate 413 is greater than the distance between the central axis 9 and the top middle position P1 of the top flat plate 411, which is upwardly adjacent to the first intermediate flat plate 413. The distance between the central axis 9 and the second middle position P3 of the second intermediate flat plate 414 is greater than the distance between the central axis 9 and the first middle position P2 of the first intermediate flat plate 413, which is upwardly adjacent to the second intermediate flat plate 414. The distance between the central axis 9 and the third middle position P4 of the third intermediate flat plate 415 is greater than the distance between the central axis 9 and the second middle position P3 of the second intermediate flat plate 414. The distance between the central axis 9 and the fourth middle position P5 of the fourth intermediate flat plate 416 is greater than the distance between the central axis 9 and the third middle position P4 of the third intermediate flat plate 415.

[0067] As described above, the radial middle of the air blowing region is gradually shifted radially outward from the top flat plate 411 to the fourth intermediate flat plate 416. In particular, in this blower apparatus 1, the area of the air blowing region gradually increases from the top flat plate 411 to the fourth intermediate flat plate 416. Accordingly, the static pressure in each axial gap 400 improves with decreasing height.

[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 flat plates 410 at lower positions are arranged to have larger air blowing regions, so that stronger air flows are generated in the axial gaps 400 at lower positions. Thus, the air flows passing through the air holes 60 are drawn downward. 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 this blower apparatus 1, each of the flat plates 410 is arranged to have an outside diameter greater than the outside diameter of the upwardly adjacent one of the flat plates 410. Note, however, that at least one of the flat plates 410 may alternatively be arranged to have an outside diameter equal to the outside diameter of the upwardly adjacent one of the flat plates 410. Even in that case, similar beneficial effects can be achieved if the bottom flat plate 412 is arranged to have an outside diameter greater than the outside diameter of the top flat plate 411, and at least one of the flat plates 410 is arranged to have an outside diameter greater than the outside diameter of the upwardly adjacent one of the flat plates 410.

[0072] 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.

[0073] In the present preferred embodiment, the top flat-plate 411 and all the intermediate flat plates 413 to 416 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.

[0074] 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".

2. Example Modifications

[0075] 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.

[0076] 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 arranged with an axial gap 400A defined between adjacent ones of the flat plates 410A. The flat plates 410A include a top flat plate 411A, a first intermediate flat plate 413A, a second intermediate flat plate 414A, a third intermediate flat plate 415A, a fourth intermediate flat plate 416A, and a bottom flat plate 412A, which are arranged in the order named from top to bottom. Each of the top flat plate 411A and the intermediate flat plates 413A to 416A includes air holes 60A and an air blowing region which is a region radially outside of the air holes 60A.

[0077] The bottom flat plate 412A is arranged to have an outside diameter greater than an outside diameter of the top flat plate 411A. In addition, an inner end portion of the air blowing region of each of the top flat plate 411A and the intermediate flat plates 413A to 416A is arranged at the same radial position. In addition, each of the flat plates 410A is arranged to have an outside diameter greater than an outside diameter of an upwardly adjacent one of the flat plates 410A. Accordingly, a distance between a central axis 9A and a radial middle position P5A of the air blowing region of the fourth intermediate flat plate 416A is greater than a distance between the central axis 9A and a radial middle position P1A of the air blowing region of the top flat plate 411A. In addition, a distance between the central axis 9A and a radial middle position P2A, P3A, P4A, or P5A of the air blowing region of each of the intermediate flat plates 413A, 414A, 415A, and 416A is greater than a distance between the central axis 9A and the radial middle position P1A, P2A, P3A, or P4A of the air blowing region of an upwardly adjacent one of the flat plates 410A.

[0078] As described above, the radial middle of the air blowing region is gradually shifted radially outward from the top flat plate 411A to the fourth intermediate flat plate 416A. In particular, in this blower apparatus 1A, the area of the air blowing region gradually increases from the top flat plate 411A to the fourth intermediate flat plate 416A. Accordingly, static pressure in each axial gap 400A improves with decreasing height.

[0079] Here, the bottom flat plate 412A is arranged to axially overlap with a lower plate portion 21A of a housing 20A. Accordingly, a sufficient axial distance needs to be secured between the bottom flat plate 412A and the lower plate portion 21A to prevent, a contact between the bottom flat plate 412A and the lower plate portion 21A. However, when there is a large axial distance between the bottom flat plate 412A and the lower plate portion 21A, air flows traveling radially outward will be unevenly distributed in the axial direction with more of the air flows in an upper portion of an interior of the housing 20A than in a lower portion thereof. If flows of air are unevenly distributed in the axial direction in the vicinity of an air outlet, the air flows may not be discharged radially outward in a straight manner.

[0080] As illustrated in the enlarged view in FIG. 6, in the blower apparatus 1A, an outer end surface 601A of each flat plate 410A is angled radially outward with decreasing height. Accordingly, an air flow traveling along an upper surface of the flat plate 410A is guided downward. This contributes to preventing air flows traveling radially outward on a radially outer side of the air blowing portion 40A from being unevenly distributed in the axial direction with more of the air flows in the upper portion of the interior of the housing 20A than in the lower portion thereof. This allows the air flows to travel in a straight manner, which leads to improved air exhaust efficiency and an increased volume of air being discharged, which results in improved air blowing efficiency.

[0081] 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 arranged with an axial gap 400B defined between adjacent ones of the flat plates 410B. The flat plates 410B include a top flat plate 411B, a first intermediate flat plate 413B, a second intermediate flat plate 414B, a third intermediate flat plate 415B, a fourth intermediate flat plate 416B, and a bottom flat plate 412B, which are arranged in the order named from top to bottom. Each of the top flat plate 411B and the intermediate flat plates 413B to 416B includes air holes 60B and an air blowing region which is a region radially outside of the air holes 60B.

[0082] In this blower apparatus 1B, all the flat plates 410B are arranged to have the same outside diameter. In addition, a distance between a central axis 9B and a radially outer end of each of the air holes 60B that are arranged at the lowest position of all the air holes 60B is arranged to be greater than a distance between the central axis 9B and a radially outer end of each of the air holes 60B that are arranged at the highest position of all the air holes 60B. That is, a radially outer end of each of the air holes 60B of the fourth intermediate flat plate 416B is arranged radially outward of a radially outer end of each of the air holes 60B of the top flat plate 411B. In addition, a distance between the central axis 9B and a radially outer end of each of the air holes 60B is arranged to be greater than a distance between the central axis 9B and a radially outer end of an upwardly adjacent one of the air holes 60B. That is, the radially outer end of each of the air holes 60B of each of the intermediate flat plates 413B to 416B is arranged radially outward of the radially outer end of each of the air holes 60B of an upwardly adjacent one of the flat plates 410B.

[0083] Accordingly, a distance between the central axis 9B and a radial middle position P5B of the air blowing region of the fourth intermediate flat plate 416B is greater than a distance between the central axis 9B and a radial middle position P1B of the air blowing region of the top flat plate 411B. In addition, a distance between the central axis 9B and a radial middle position P2B, P3B, P4B, or P5B of the air bio-wing region of each of the intermediate flat plates 413B, 414B, 415B, and 416B is greater than a distance between the central axis 9B and the radial middle position P1B, P2B, P3B, or P4B of the air blowing region of an upwardly adjacent, one of the flat plates 410B.

[0084] Air flows passing downward through the air holes 60B of the flat plates 410B are drawn radially outward in the axial gaps 400B. In this blower apparatus 1B, the radially outer ends of the air holes 60B at lower positions are arranged more radially outward, and thus, gas supplied from above can be supplied to the bottom flat plate 412B, which is arranged at the lowest position, through the air holes 60B. This leads to improved air intake efficiency and improved air blowing efficiency.

[0085] In this blower apparatus 1B, the distance between the central axis 9B and the radially outer end of each of the air holes 60B of each of the top flat plate 411B and the intermediate flat plates 413B to 416B is greater than the distance between the central axis 9B and the radially outer end of each of the air holes 60B of the upwardly adjacent one of the flat plates 410B. Note, however, that the distance between the central axis 9B and the radially outer end of each of the air holes 60B of at least one of the flat plates 410B may alternatively be equal to the distance between the central axis 9B and the radially outer end of each of the air holes 60B of the upwardly adjacent, one of the flat plates 410B. Even in that, case, similar beneficial effects can be achieved if the distance between the central axis 9B and the radially outer end of each of the air holes 60B of the fourth intermediate flat plate 416B, i.e., the air holes 60B that are arranged at the lowest position of all the air holes 60B, is greater than the distance between the central axis 9B and the radially outer end of each of the air holes 60B of the top flat plate 411B, i.e., the air holes 60B that are arranged at the highest position of all the air holes 60B, and the distance between the central axis 9B and the radially outer end of each of the air holes 60B of at least one of the flat plates 410B is greater than the distance between the central axis 9B and the radially outer end of each of the air holes 60B of the upwardly adjacent one of the flat plates 410B.

[0086] 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 arranged with an axial gap 400C defined between adjacent ones of the flat plates 410C. The flat plates 410C include a top flat plate 411C, a first intermediate flat plate 413C, a second intermediate flat plate 414C, a third intermediate flat plate 415C, a fourth intermediate flat plate 416C, and a bottom flat plate 412C, which are arranged in the order named from top to bottom. Each of the top flat plate 411C and the intermediate flat plates 413C to 416C includes air holes 60C and an air blowing region which is a region radially outside of the air holes 60C.

[0087] In this blower apparatus 1C, all the flat plates 410C are arranged to have the same outside diameter, as in the blower apparatus 1B according to the modification illustrated in FIG. 7. In addition, a distance between a central axis 9C and a radially outer end of each of the air holes 60C that are arranged at the lowest position of all the air holes 60C is arranged to be greater than a distance between the central axis 9C and a radially outer end of each of the air holes 60C that are arranged at the highest position of all the air holes 60C. That is, a radially outer end of each of the air holes 60C of the fourth intermediate flat plate 416C is arranged radially outward of a radially outer end of each of the air holes 60C of the top flat plate 411C. In addition, a distance between the central axis 9C and a radially outer end of each of the air holes 60C is arranged to be greater than a distance between the central axis 9C and a radially outer end of an upwardly adjacent one of the air holes 60C. That is, the radially outer end of each of the air holes 60C of each of the intermediate flat plates 413C to 416C is arranged radially outward of the radially outer end of each of the air holes 60C of an upwardly adjacent one of the flat plates 410C.

[0088] As illustrated in the enlarged view in FIG. 8, in this blower apparatus 1C, each of the top flat plate 411C and the intermediate flat plates 413C to 416C includes end surfaces 602C each of which defines an outer edge of a separate one of the air holes 60C, and each of the end surfaces 602C is angled radially outward with decreasing height. Thus, air flows passing downward through the air holes 60C of the flat plates 410C are guided along the end surfaces 602C and along lower surfaces of the top flat plate 411C and the intermediate flat plates 413C to 416C. That is, the air flows passing downward through the air holes 60C can easily travel into the axial gaps 400C between the flat plates 410C. This leads to improved air intake efficiency, which results in improved air blowing efficiency.

[0089] 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 arranged with an axial gap 400D defined between adjacent ones of the flat plates 410D. The flat plates 410D include a top flat plate 411D, a first intermediate flat plate 413D, a second intermediate flat plate 414D, a third intermediate flat plate 415D, a fourth intermediate flat plate 416D, and a bottom flat plate 412D, which are arranged in the order named from top to bottom. Each of the top flat plate 411D and the intermediate flat plates 413D to 416D includes air holes 60D and an air blowing region which is a region radially outside of the air holes 60D.

[0090] The bottom flat plate 412D is arranged to have an outside diameter greater than an outside diameter of the top flat plate 411D. In addition, each of the flat plates 410D is arranged to have an outside diameter greater than an outside diameter of an upwardly adjacent one of the flat plates 410D. Thus, improvements in air intake efficiency and air blowing efficiency can be achieved as is similarly the case with the blower apparatus 1 according to the above-described preferred embodiment and the blower apparatus 1A according to the modification illustrated in FIG. 6.

[0091] In addition, a distance between a central axis 9D and a radially outer end of each of the air holes 60D that are arranged at the lowest position of all the air holes 60D is arranged to be greater than a distance between the central axis 9D and a radially outer end of each of the air holes 60D that are arranged at the highest position of all the air holes 60D. That is, a radially outer end of each of the air holes 60D of the fourth intermediate flat plate 416D is arranged radially outward of a radially outer end of each of the air holes 60D of the top flat plate 411D. In addition, a distance between the central axis 9D and a radially outer end of each of the air holes 60D is arranged to be greater than a distance between the central axis 9D and a radially outer end of an upwardly adjacent one of the air holes 60D. That is, the radially outer end of each of the air holes 60D of each of the intermediate flat plates 413D to 416D is arranged radially outward of the radially outer end of each of the air holes 60D of an upwardly adjacent one of the flat plates 410D. Thus, improvements in air intake efficiency and air blowing efficiency can be achieved as is similarly the case with the blower apparatus 1B according to the modification illustrated in FIG. 7 and the blower apparatus 1C according to the modification illustrated in FIG. 8.

[0092] Accordingly, a distance between the central axis 9D and a radial middle position P5D of the air blowing region of the fourth intermediate flat plate 416D is greater than a distance between the central axis 9D and a radial middle position P1D of the air blowing region of the top flat plate 411D. In addition, a distance between the central axis 9D and a radial middle position P2D, P3D, P4D, or P8D of the air blowing region of each of the intermediate flat plates 413D, 414D, 415D, and 416D is greater than a distance between the central axis 9D and the radial middle position P1D, P2D, P3D, or P4D of the air blowing region of an upwardly adjacent one of the flat plates 410D. As described above, the radial middle of the air blowing region is gradually shifted radially outward from the top flat plate 411D to the fourth intermediate flat plate 416D. This leads to improved air blowing efficiency.

[0093] 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, a motor portion 30E includes a stationary portion 31E, a rotating portion 32E, and two ball bearings 33E.

[0094] The stationary portion 31E includes a stator fixing portion 311E and a stator 312E. The stator fixing portion 311E is a member being cylindrical and having a closed bottom and fixed to a housing 20E. The stator 312E is an armature fixed to an outer circumferential surface of the stator fixing portion 31IE.

[0095] The rotating portion 32E includes a shaft 321E, a hub 322E, and a magnet 324E. At least a lower end portion of the shaft 321E is arranged inside of the stator fixing portion 311E. In addition, an upper end portion of the shaft 321E is fixed to the hub 322E. The magnet 324E is fixed to the hub 322E. The magnet 324E is arranged radially opposite to the stator 312E.

[0096] Each ball bearing 33E is arranged to connect the rotating portion 32E to the stationary portion 31E such that the rotating portion 32E is rotatable with respect to the stationary portion 31E. Specifically, an outer race of each ball bearing 33E is fixed to an inner circumferential surface of the stator fixing portion 311E of the stationary portion 31E. In addition, an inner race of each ball bearing 33E is fixed to an outer circumferential surface of the shaft 321E of the rotating portion 32E. 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 30E.

[0097] In the modification illustrated in FIG. 10, the motor portion 30E includes the two ball bearings 33E. The ball bearings 33E 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 311E and the shaft 321E are opposed to each other. This contributes to preventing the shaft 321E from being inclined with respect to a central axis 9E.

[0098] FIG. 11 is a top 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, a housing 20F includes a plurality of air outlets 201F. Specifically, a side wall portion 22F includes the air outlets 201F, each of which is arranged to face in a radial direction, at a plurality of circumferential positions. The housing 20F includes tongue portions 203F, each of which is arranged near a separate one of the air outlets 201F. In addition, an air blowing portion 40F includes a plurality of flat plates 410F arranged in the axial direction with an axial gap defined between adjacent ones of the flat plates 410F.

[0099] 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 1F, air flows traveling radially outward are generated by rotation of the flat plates 410F, and therefore, the blower apparatus 1F is able to achieve reduced periodic noise when compared to the centrifugal fan including the impeller. Therefore, the blower apparatus 1F, which is designed to discharge air in a plurality of directions, does not significantly deteriorate in noise characteristics due to the tongue portions 203F.

[0100] 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.

[0101] 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.

[0102] 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.

[0103] Preferred embodiments of the present invention are applicable to blower apparatuses.

[0104] 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.

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