Blower apparatus

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; a clamper portion fixed to the motor portion; and a housing arranged to house the air blowing portion and the motor portion. The housing includes an air inlet and an air outlet. The air blowing portion is held by the motor portion and the clamper portion from upper and lower sides in the 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.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a blower apparatus.

2. Description of the Related Art

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.

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

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.

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.

An object of the present invention is to provide a technique for realizing a centrifugal blower apparatus which is excellent in air blowing efficiency.

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 having at least a portion thereof arranged on a lower side of the air blowing portion; a clamper portion fixed to the motor portion, and having at least a portion thereof arranged on an upper side of 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 air blowing portion is held by the motor portion and the clamper portion from upper and lower sides in the axial direction.

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 an 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. Further, since the air blowing portion and the motor portion are securely fixed to each other by the clamper portion, the air blowing portion is able to stably rotate. This leads to an improvement in the air blowing efficiency and an additional reduction in noise.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

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

FIG. 1is a perspective view of a blower apparatus1according to a first, preferred embodiment of the present invention.FIG. 2is a top view of the blower apparatus1.FIG. 3is a sectional view of the blower apparatus1taken along line A-A inFIG. 2.FIG. 4is an exploded perspective view of the blower apparatus1.FIG. 5is a partial sectional view of the blower apparatus1. The blower apparatus1is a centrifugal blower apparatus designed to generate an air flow traveling radially outward by rotating an air blowing portion40. The blower apparatus1is, for example, installed in an electronic device, such as, for example, a personal computer, to cool an interior thereof. Note that the blower apparatus1according to a preferred embodiment of the present invention may alternatively be used for other purposes.

Referring toFIGS. 1 to 4, the blower apparatus1includes a housing20, a motor portion30, the air blowing portion40, and a clamper portion50.

The housing20is a case arranged to house the motor portion30and the air blowing portion40. The housing20includes a lower plate portion21, a side wall portion22, and an upper plate portion23.

The lower plate portion21is arranged to define a bottom portion of the housing20. The lower plate portion21is arranged to extend radially below the air blowing portion40to cover at least a portion of a lower side of the air blowing portion40. In addition, the lower plate portion21is arranged to support the motor portion30.

The side wall portion22is arranged to extend upward from the lower plate portion21. The side wall portion22is arranged to cover a lateral side of the air blowing portion40between the lower plate portion21and the upper plate portion23. In addition, the side wall portion22includes an air outlet201arranged to face in a radial direction at one circumferential position. In the present preferred embodiment, the lower plate portion21and the side wall portion22are defined integrally with each other. Note that the lower plate portion21and the side wall portion22may alternatively be defined by separate members.

The upper plate portion23is arranged to define a cover portion of the housing20. The upper plate portion23is arranged to extend radially above the lower plate portion21. In addition, the upper plate portion23includes an air inlet202arranged to pass therethrough in an axial direction. In other words, the upper plate portion23includes an inner edge portion231arranged to define the air inlet202. The air inlet202is, for example, circular and is centered on a central axis9in a plan view.

The motor portion30is a driving portion arranged to rotate the air blowing portion40. Referring toFIG. 5, the motor portion30includes a stationary portion31and a rotating portion32. The stationary portion31is fixed to the lower plate portion21. The stationary portion31is thus arranged to be stationary relative to the housing20. The rotating portion32is supported to be rotatable about the central axis9with respect to the stationary portion31.

The stationary portion31includes a stator fixing portion311, a stator312, and a bearing housing313.

The stator fixing portion311is fitted in a fixing hole211defined in the lower plate portion21. As a result, the stator fixing portion311is fixed to the lower plate portion21. The stator fixing portion311is arranged to extend upward from the fixing hole211to assume a cylindrical shape with the central axis9as a center thereof. The stator312is fixed to an outer circumferential portion of an upper portion of the stator fixing portion311.

The stator312is an armature arranged to generate magnetic flux in accordance with electric drive currents supplied from an external source. The stator312is arranged to annularly surround the central axis9, which extends in a vertical direction. The stator312includes, for example, an annular stator core defined by laminated steel sheets, and conducting wires wound around the stator core.

The bearing housing313is a member being cylindrical and having a closed bottom. Specifically, the bearing housing313includes a disk-shaped bottom portion, and a cylindrical portion arranged to extend upward from the bottom portion. The bearing housing313is fixed to an inner circumferential surface of the stator fixing portion311.

The rotating portion32includes a shaft321, a hub322, a bearing member323, and a magnet324.

The shaft321is a member arranged to extend along the central axis9. The shaft321according to the present preferred embodiment includes a columnar portion arranged inside of a first cylindrical portion612, which will be described below, and arranged to extend with the central axis9as a center thereof, and a disk-shaped portion arranged to extend radially from a lower end portion of the columnar portion.

The hub322is fixed to the shaft321. The hub322is made up of a hub body member61and a flange member62.

The hub body member61includes a first top plate portion611, the first cylindrical portion612, a second cylindrical portion613, and a magnet holding portion614.

The first top plate portion611is a disk-shaped portion arranged to extend radially with the central axis9as a center thereof. The first top plate portion611is arranged above the stator312. The first top plate portion611has a fixing hole610arranged to pass therethrough in the vertical direction in a center thereof.

The first cylindrical portion612is arranged to extend downward from an inner edge portion of the first top plate portion611which defines the fixing hole610to assume a cylindrical shape with the central axis9as a center thereof. The columnar portion of the shaft321is housed in the first cylindrical portion612. In addition, the shaft321is fixed to the first cylindrical portion612.

The second cylindrical portion613is arranged to extend downward from the first top plate portion611to assume a cylindrical shape with the central axis9as a center thereof. The second cylindrical portion613is arranged to have an inside diameter greater than an outside diameter of the first cylindrical portion612. In other words, the second cylindrical portion613is arranged radially outside of the first cylindrical portion612.

The magnet holding portion614is arranged to extend downward from a radially outer end of the first top plate portion611to assume a cylindrical shape with the central axis9as a center thereof. The magnet holding portion614is arranged radially outside of the stator312. The magnet324is fixed to an inner circumferential surface of the magnet holding portion614.

The flange member62includes an outer wall portion621, a second top plate portion622, and a flat plate holding portion623.

The outer wall portion621is a cylindrical portion arranged to extend in the vertical direction with the central axis9as a center thereof. The outer wall portion621is arranged to extend along an outer circumferential surface of the magnet holding portion614of the hub body member61.

The second top plate portion622is arranged to extend radially inward from an upper end portion of the outer wall portion621to assume the shape of a circular ring. The second top plate portion622is arranged on an upper surface of the first top plate portion611of the hub body member61. The second top plate portion622is thus arranged to cover a portion of an upper surface of the hub body member61.

The flat plate holding portion623is arranged to extend radially outward from a lower end portion of the outer wall portion621. The flat plate holding portion623is arranged to hold the air blowing portion40on a radially outer side of the magnet holding portion614of the hub body member61. In the present, preferred embodiment, the air blowing portion40is mounted on an upper surface of the flat plate holding portion623. The flat plate holding portion623is thus arranged to hold a plurality of flat plates410included in the air blowing portion40.

The bearing member323is a cylindrical member arranged to extend in the vertical direction with the central axis3as a center thereof. The bearing member323is arranged to extend along an outer circumferential surface of the first cylindrical portion612of the hub body member61. In addition, the bearing member323is fixed to the outer circumferential surface of the first cylindrical portion612. The cylindrical portion of the bearing housing313is arranged radially outside of the bearing member323and radially inside of the second cylindrical portion613of the hub body member61.

The magnet324is fixed to the inner circumferential surface of the magnet holding portion614of the hub body member61. In addition, the magnet324is arranged radially outside of the stator312. The magnet324according to the present preferred embodiment is in the shape of a circular ring. A radially inner surface of the magnet324is arranged radially opposite to the stator312with a slight gap therebetween. In addition, an inner circumferential surface of the magnet324includes 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 magnet324in 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.

As illustrated in an enlarged view inFIG. 5, a lubricating fluid300is arranged between the bearing housing313and a combination of the shaft321, the bearing member323, and the hub body member61. A polyolester oil or a diester oil, for example, is used as the lubricating fluid300. The shaft321, the hub322, and the bearing member323are supported to be rotatable with respect to the bearing housing313through the lubricating fluid300. Thus, in the present preferred embodiment, the bearing housing313, which is a component of the stationary portion31, the combination of the shaft321, the bearing member323, and the hub body member61, each of which is a component of the rotating portion32, and the lubricating fluid300together define a fluid dynamic bearing.

A surface of the lubricating fluid300is defined in a seal portion301, which is a gap between an outer circumferential surface of the bearing housing313and an inner circumferential surface of the second cylindrical portion613of the hub body member61. In the seal portion301, the distance between the outer circumferential surface of the bearing housing313and the inner circumferential surface of the second cylindrical portion613is arranged to increase with decreasing height. In other words, in the seal portion301, the distance between the outer circumferential surface of the bearing housing313and the inner circumferential surface of the second cylindrical portion613is arranged to increase with increasing distance from the surface of the lubricating fluid300. Since the radial width of the seal portion301thus increases with decreasing height, the lubricating fluid300is attracted upward in the vicinity of the surface of the lubricating fluid300. This reduces the likelihood that the lubricating fluid300will leak out of the seal portion301.

Use of the fluid dynamic bearing as a bearing mechanism that connects the stationary portion31and the rotating portion32allows the rotating portion32to rotate stably. Thus, the likelihood of an occurrence of an unusual sound from the motor portion30can be reduced.

Once electric drive currents are supplied to the stator312in the motor portion30as described above, magnetic flux is generated around the stator312. Then, interaction between the magnetic flux of the stator312and magnetic flux of the magnet324produces a circumferential torque between the stationary portion31and the rotating portion32, so that the rotating portion32is caused to rotate about the central axis9with respect to the stationary portion31. The air blowing portion40, which is held by the flat plate holding portion623of the rotating portion32, is caused to rotate about the central axis9together with the rotating portion32.

Referring toFIGS. 4 and 5, the air blowing portion40includes the plurality of flat plates410and a plurality of spacers420. The flat plates410and the spacers420are arranged to alternate with each other in the axial direction. In addition, adjacent ones of the flat plates410and the spacers420are fixed to each other through, for example, adhesion.

Referring toFIGS. 4 and 5, in the present preferred embodiment, the flat plates410include a top flat plate411, which is arranged at the highest position, a bottom flat plate412, which is arranged at the lowest position, and four intermediate flat plates413, which are arranged below the top flat plate411and above the bottom flat plate412. That is, the number of flat plates410included in the air blowing portion40according to the present preferred embodiment is six. The flat plates410are arranged in the axial direction with an axial gap400defined between adjacent ones of the flat plates410.

Each flat plate410is made of, for example, a metal material, such as stainless steel, or a resin material. Each flat plate410may 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 plate410is able to achieve higher dimensional accuracy when the flat plate410is made of a metal material than when the flat plate410is made of a resin material.

In the present preferred embodiment, each of the top flat plate411and the four intermediate flat plates413is arranged to have the same shape and size. Referring toFIGS. 1, 2, and 5, each of the top flat plate411and the intermediate flat plates413includes an inner annular portion71, an outer annular portion72, a plurality of ribs73, and a plurality of air holes70. In the present preferred embodiment, the number of ribs73and the number of air holes70included in each of the top flat plate411and the intermediate flat plates413are both five.

The inner annular portion71is an annular portion centered on the central axis9. The inner annular portion71has a central hole75(seeFIG. 4) arranged to pass therethrough in the vertical direction in a center thereof. The outer annular portion72is an annular portion arranged radially outside of the inner annular portion71with the central axis9as a center thereof. Each rib73is arranged to join the inner annular portion71and the outer annular portion72to each other. Each air hole70is arranged to be in communication with a space radially outside of the air blowing portion40through the axial gap(s)400adjacent to the flat plate410including the air hole70on the upper and/or lower sides of the flat plate410. Each air hole70is arranged at a position overlapping with the air inlet202of the housing20when viewed in the axial direction.

The bottom flat plate412is an annular and plate-shaped member centered on the central axis9. The bottom flat plate412has a central hole75arranged to pass therethrough in the vertical direction in a center thereof.

Referring toFIG. 4, each spacer420is a member in the shape of a circular ring. The spacers420are arranged between the flat plates410to secure the axial gaps400between the flat plates410. Each spacer420has a central hole429arranged to pass therethrough in the vertical direction in a center thereof. The motor portion30is arranged in the central holes75of the flat plates410and the central holes429of the spacers420.

Each spacer420is arranged at a position axially coinciding with the inner annular portion71of each of the top flat plate411and the intermediate flat plates413. Thus, the spacer420is arranged in a region in the corresponding axial gap400, the region covering only a portion of the radial extent of the corresponding axial gap400. Notice that, in this blower apparatus1, one of the spacers420is arranged on an upper side of the top flat plate411.

The clamper portion50includes a cover portion51and a clamping portion52.

The cover portion51is a member in the shape of a disk. The cover portion51is arranged to cover an upper side of the motor portion30and an upper side of a portion of the radial extent of the air blowing portion40. That is, at least a portion of the cover portion51is arranged on the upper side of the air blowing portion40. In addition, the cover portion51includes a fitting hole510at a position overlapping with the central axis9.

The cover portion51includes a central portion511arranged most radially inward, a first annular portion512arranged radially outside of the central portion511, and a second annular portion513arranged radially outside of the first annular portion512. A lower surface of the central portion511is arranged along the upper surface of the first top plate portion611of the hub body member61of the hub322. A lower surface of the first annular portion512is arranged along an upper surface of the second top plate portion622of the flange member62. A lower surface of the second annular portion513is arranged along an upper surface of the spacer420that is arranged at the highest position in the air blowing portion40.

The lower surface of the first annular portion512is arranged at a level higher than that of the lower surface of the central portion511and that of the lower surface of the second annular portion513. Thus, the lower surface of the cover portion51includes a recessed portion514recessed upward axially above the second top plate portion622within a radial range of the first annular portion512. Then, the second top plate portion622is arranged in the recessed portion514. With the cover portion51including the recessed portion514in which the second top plate portion622is arranged as described above, the axial thickness of the clamper portion50is minimized. This contributes to reducing the axial dimension of the blower apparatus1and the weight of the blower apparatus1.

The clamping portion52is inserted into the fitting hole510of the cover portion51and the fixing hole610of the hub body member61of the hub322. As a result, the clamping portion52fixes the cover portion51and the hub body member61to each other. That, is, the clamping portion52is arranged to fix the cover portion51and the motor portion30to each other. In addition, the shaft321of the motor portion30and the clamping portion52are arranged axially opposite to each other with a gap therebetween inside of the first cylindrical portion612of the hub body member61.

With the above arrangement, the air blowing portion40is held by the flat plate holding portion623of the flange member62of the hub322and the second annular portion513of the cover portion51from the upper and lower sides in the axial direction. That is, the air blowing portion40is held by the motor portion30and the clamper portion50from the upper and lower sides in the axial direction. With the air blowing portion40being thus held and fixed from the upper and lower sides, the air blowing portion40and the motor portion30can be securely fixed to each other. As a result, the air blowing portion40is able to stably rotate, achieving an improvement in air blowing efficiency of the blower apparatus1.

In this blower apparatus1, the cover portion51includes a plurality of hole portions515each of which is arranged to pass therethrough in the axial direction. More specifically, six of the hole portions515are defined in the first annular portion512. In addition, six of the hole portions515are defined in the second annular portion513. As a result, the weight of the cover portion51is reduced. Thus, an additional reduction in the weight of the blower apparatus1is achieved. Note that the cover portion51may be arranged to include recess portions each of which is recessed from an upper surface thereof in place of the hole portions515. Even in this case, a reduction in the weight of the cover portion51can be achieved.

Referring toFIG. 5, the second annular portion513, which includes an outer end portion of the cover portion51, defines a flange holding portion arranged radially outside of the recessed portion514and the second top plate portion622, and arranged to radially overlap with the second top plate portion622. With the second annular portion513being arranged to radially overlap with the second top plate portion622, durability of a rotating body including the rotating portion32of the motor portion30, the air blowing portion40, and the clamper portion50is improved.

Once the motor portion30is driven, the air blowing portion40and the clamper portion50are caused to rotate together with the rotating portion32. As a result, viscous drag of a surface of each flat plate410and a centrifugal force together generate an air flow traveling radially outward in the vicinity of the surface of the flat plate410. Thus, an air flow traveling radially outward is generated in each of the axial gaps400between the flat plates410. Thus, gas above the housing20is supplied to each axial gap400through the air inlet202of the housing20and the air holes70of the top flat plate411and the intermediate flat plates413, and is discharged out of the blower apparatus1through the air outlet201, which is defined in a side portion of the housing20.

Here, each flat plate410is arranged to have an axial thickness of about 0.1 mm. Meanwhile, each axial gap400is arranged to have an axial dimension of about 0.3 mm. The axial dimension of the axial gap400is preferably in the range of 0.2 mm to 0.5 mm. An excessively large axial dimension of the axial gap400would lead to a separation between an air flow generated by a lower surface of the flat plate410on the upper side and an air flow generated by an upper surface of the flat plate410on the lower side during rotation of the air blowing portion40. This separation could result in a failure to generate sufficient, static pressure in the axial gap400to discharge a sufficient volume of air. Moreover, an excessively large axial dimension of the axial gap400would make it difficult to reduce the axial dimension of the blower apparatus1. Accordingly, in this blower apparatus1, the axial dimension of the axial gap400is arranged to be in the range of 0.2 mm to 0.5 mm. This arrangement allows the blower apparatus1to achieve a reduced thickness while allowing an increase in the static pressure in the axial gap400to discharge a sufficient volume of air.

Each of the fop flat plate411and the intermediate flat plates413includes the air holes70. Accordingly, in each of the top flat plate411and the intermediate flat plates413, the outer annular portion72, which is arranged radially outside of the air holes70, defines an air blowing region which generates an air flow in the vicinity of a surface thereof. Meanwhile, the bottom flat plate412includes no air hole70. Therefore, in an upper surface of the bottom flat plate412, an entire region radially outside of a portion of the bottom flat plate412which makes contact with the spacer420defines an air blowing region. In other words, in the upper surface of the bottom flat plate412, a region which axially coincides with the air holes70and the ribs73of the top flat plate411and the intermediate flat plates413, and a region which axially coincides with the outer annular portions72thereof, together define the air blowing region. In addition, in a lower surface of the bottom flat plate412, an entire region radially outside of a portion of the bottom flat plate412which makes contact with the flat plate holding portion623defines an air blowing region. Notice that an air flow is generated by a lower surface of the flat plate holding portion623as well.

As described above, the bottom flat plate412has air blowing regions wider than the air blowing regions of the top flat plate411and the intermediate flat plates413. Therefore, the axial gap400between the lowest one of the intermediate flat plates413and the bottom flat plate412is able to have higher static pressure than any other axial gap400.

Air flows passing downward through the air inlet202and the air holes70are drawn radially outward in each axial gap400. Therefore, the air flows passing through the air holes70become weaker as they travel downward. In the present preferred embodiment, the bottom flat plate412is arranged to have an air blowing region wider than the air blowing regions of the top flat plate411and the intermediate flat plates413to cause a stronger air flow to be generated in the lowest one of the axial gaps400than in any other axial gap400to cause the air flows passing downward through the air holes70to be drawn toward the lowest axial gap400. Thus, a sufficient volume of gas is supplied to the lowest axial gap400as well. As a result, the air blowing portion40achieves improved air blowing efficiency.

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 apparatus1according to the present preferred embodiment, the air flows are generated in the vicinity of the surfaces of the flat plates410, and therefore, the air flows do not easily leak upward or downward. Therefore, even when the axial dimension of the air blowing portion40, 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 apparatus1has a reduced thickness, a reduction in air blowing efficiency thereof does not easily occur.

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 apparatus1is 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 plate410and the centrifugal force in the blower apparatus1.

In addition, from the viewpoint of P-Q characteristics (i.e., flow rate-static pressure characteristics), the blower apparatus1including the flat plates410is 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 apparatus1is 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.

In the present preferred embodiment, the top flat plate411and all the intermediate flat plates413include the air holes70. Accordingly, all the axial gaps400are in axial communication with a space above the housing20through the air inlet202and the air holes70.

Referring toFIG. 2, the air inlet202is centered on the central axis9. That is, a center of the air inlet202coincides with the central axis9. Meanwhile, the air blowing portion40is also centered on the central axis9. Accordingly, differences in pressure do not easily occur at different circumferential positions in the air blowing portion40. 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

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.

FIG. 6is a perspective view of a blower apparatus1A according to a modification of the above-described preferred embodiment.FIG. 7is a top view of the blower apparatus1A according to the modification illustrated inFIG. 6.FIG. 8is a partial sectional view of the blower apparatus1A according to the modification illustrated inFIG. 6. The blower apparatus1A according to the modification illustrated inFIGS. 6 to 8includes a motor portion30A, an air blowing portion40A, and a clamper portion50A. The motor portion30A includes a stationary portion31A and a rotating portion32A. The stationary portion31A includes a stator312A, which is an armature. The rotating portion32A includes a magnet324A arranged radially outside of the stator312A, and a hub322A arranged to hold the magnet324A.

The hub322A is made up of a hub body member61A and a flange member62A. The hub body me miser61A includes a first top plate portion611A and a magnet holding portion614A. The first top plate portion611A is arranged to cover an upper side of the stator312A. The magnet holding portion614A is arranged to hold the magnet324A with an inner circumferential surface thereof. The flange member62A includes an outer wall portion621A, second top plate portions622A, and a flat plate holding portion623A. The flat plate holding portion623A is arranged to hold the air blowing portion40A on a radially outer side of the magnet holding portion614A. The outer wall portion621A is arranged to extend upward from the flat plate holding portion623A along an outer circumferential surface of the magnet holding portion614A. Each second top plate portion622A is arranged to extend radially inward from an upper end of the outer wall portion621A, and is arranged along an upper surface of the first top plate portion611A.

The clamper portion50A includes a cover portion51A and a clamping portion52A. The cover portion51A includes a center portion516A including a fitting hole510A, and a plurality of arm portions517A arranged to extend in a radial manner from the center portion516A. At least a portion of each arm portion517A is arranged on the upper side of the air blowing portion40A. Thus, the air blowing portion40A is held by the flat plate holding portion623A of the motor portion30A and the arm portions517A of the clamper portion50A from the upper and lower sides in the axial direction. The air blowing portion40A and the motor portion30A are thus securely fixed to each other. With the cover portion51A being defined by the center portion516A and the arm portions517A as described above, a reduction in volume of the cover portion51A is achieved. Accordingly, a reduction in weight of the blower apparatus1A is achieved.

In this blower apparatus1A, the second top plate portions622A are spaced from one another in the circumferential direction. On the upper surface of the first top plate portion611A, the second top plate portions622A and the arm portions517A of the cover portion51A are arranged to alternate with each other in the circumferential direction. That is, each second top plate portion622A is arranged between circumferentially adjacent ones of the arm portions517A. In addition, referring toFIG. 8, an axial position of each second top plate portion622A and an axial position of each arm portion517A are arranged to overlap with each other. This arrangement enables the blower apparatus1A to have a smaller axial dimension than in a case where the cover portion51A of the clamper portion50A is arranged on the upper side of the second top plate portions622A. Thus, a reduction in thickness of the blower apparatus1A can be achieved.

FIG. 9is a partial sectional view of a blower apparatus1B according to another modification of the above-described preferred embodiment. In the blower apparatus1B according to the modification illustrated inFIG. 9, a motor portion30B includes a stationary portion31B, a rotating portion32B, and two ball bearings33B.

The stationary portion31B includes a stator fixing portion311B and a stator312B. The stator fixing portion311B is a member being cylindrical and having a closed bottom and fixed to a housing20B. The stator312B is an armature fixed to an outer circumferential surface of the stator fixing portion311B.

The rotating portion32B includes a shaft321B, a hub322B, and a magnet324B. At least a lower end portion of the shaft321B is arranged inside of the stator fixing portion311B. In addition, an upper end portion of the shaft321B is fixed to the hub322B. The magnet324B is fixed to the hub322B. The magnet324B is arranged radially opposite to the stator312B.

Each ball bearing33B is arranged to connect the rotating portion32B to the stationary portion31B such that the rotating portion32B is rotatable with respect to the stationary portion31B. Specifically, an outer race of each ball bearing33B is fixed to an inner circumferential surface of the stator fixing portion311B of the stationary portion31B. In addition, an inner race of each ball bearing33B is fixed to an outer circumferential surface of the shaft321B of the rotating portion32B. Further, a plurality of balls, each of which is a spherical roll 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 portion30B.

In the modification illustrated inFIG. 9, the motor portion30B includes the two ball bearings33B. The ball bearings33B are arranged near an upper end and a lower end of an axial range over which the inner circumferential surface of the stator fixing portion311B and the shaft321B are opposed to each other. This contributes to preventing the shaft321B from being inclined with respect to a central axis9B.

FIG. 10is a top view of a blower apparatus1C according to yet another modification of the above-described preferred embodiment. In the blower apparatus1C according to the modification illustrated inFIG. 10, a housing20C includes a plurality of air outlets201C. Specifically, a side wall portion22C includes the air outlets201C, each of which is arranged to face in a radial direction, at a plurality of circumferential positions. The housing20C includes tongue portions203C, each of which is arranged near a separate one of the air outlets201C. In addition, an air blowing portion40C includes a plurality of flat plates410C arranged in the axial direction with an axial gap defined between adjacent ones of the flat plates410C.

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 apparatus1C, air flows traveling radially outward are generated by rotation of the flat plates410C, and therefore, the blower apparatus1C is able to achieve reduced periodic noise when compared to the centrifugal fan including the impeller. Therefore, the blower apparatus1C, which is designed to discharge air in a plurality of directions, does not significantly deteriorate in noise characteristics due to the tongue portions203C.

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.

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.

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.

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