Patent Application
20110305565
The present invention relates to an axial fan apparatus that blows air in an axial-flow direction, a housing that is used for the axial fan apparatus, and an electronic apparatus that is mounted with the axial fan apparatus.
Recently, fans are used to cool down heat generators in most electronic apparatuses such as PCs. Herein, it is necessary to increase flow rate of the fans and to reduce noise generated by the operating fans.
Japanese Patent Application Laid-open No. 2001-003900 (paragraphs 0016 and 0017, FIG. 1; hereinafter referred to as Patent Document 1) discloses an axial-flow fan including a housing (5) surrounding a fan rotor (1). Lateral slits (14) are formed to the housing (5). A width of the slits (14) is set such that laminar flows of air are generated. Patent Document 1 describes that, with this structure, generation of turbulent flows and noise are suppressed.
In order to suppress the noise, the fans should preferably be further improved. In addition, decreased noise level is strongly requested by users.
In view of the above circumstances, there is a need for an axial fan apparatus and a housing capable of suppressing noise, and an electronic apparatus mounted with the axial fan apparatus.
According to an embodiment of the present invention, there is provided an axial fan apparatus including an axial-flow impeller, a drive unit, and a housing. The axial-flow impeller is capable of rotating and includes a plurality of blades inclined with respect to a rotational axis direction. The drive unit rotates the axial-flow impeller. The housing is mounted with the drive unit, and includes a sidewall, and a plurality of slits that circulate gas. The sidewall is provided around the axial-flow impeller. The plurality of slits are provided to the sidewall and inclined with respect to the rotational axis direction in a direction opposed to a direction in which the plurality of blades incline.
In general, when an axial-flow impeller rotates, there generate airflows (hereinafter referred to as swirling flows) in the vicinity of an end portion of a blade from a surface (air discharge side) opposed to a negative pressure generation surface side (air suction side) of the blade to the negative pressure generation surface side. The swirling flows generate noise. According to this embodiment, when the axial-flow impeller rotates, air flows from the outside of the housing to the inside via the plurality of slits. Since the plurality of slits are inclined in the direction opposed to the direction in which the blades are inclined, the swirling flows are straightened. The noise can thus be suppressed.
In this embodiment, each of the plurality of blades includes an end portion at an outer circumferential side of rotation, a negative pressure generation surface that generates a negative pressure, and an auxiliary vane standing on the negative pressure generation surface at the end portion. Accordingly, the generation of the swirling flows in the vicinity of the end portions of the blades as described above can be suppressed. With the result, the noise can further be suppressed.
In this embodiment, the auxiliary vane has a height from the negative pressure generation surface smaller than twice a thickness of each of the plurality of blades. In the case that the height of the auxiliary vane is too large, when the axial-flow impeller rotates, air sucked via the slits into the housing tends to flow toward the negative pressure generation surface of the blade but is shielded by the auxiliary vanes. In this case, the function for straightening the swirling flows by the slits is deteriorated. However, since the height of the auxiliary vanes from the negative pressure generation surface is smaller than twice the thickness of the blades as described above, the swirling flows are straightened owing to the slits and suppressed owing to the auxiliary vanes in a balanced manner, and the noise level is decreased.
In this embodiment, the sidewall includes an annular inner circumferential surface and an annular outer circumferential surface. That is, the sidewall has substantially the constant thickness. Thus, compared to a sidewall including an annular inner circumferential surface and a plane outer surface, i.e., a sidewall having excessive thickness, the sidewall of this embodiment can have the slits having a larger entire opening area. The housing including the sidewall having the excessive thickness is generally a rectangular parallelepiped in most cases. Compared to the case that the slits, for example, are formed to the plane outer surface, the annular sidewall of this embodiment can have the slits larger in number. The suction amount and flow rate of the gas can thus be increased.
According to another embodiment of the present invention, there is provided a housing provided to an axial fan apparatus including an axial-flow impeller including a plurality of blades inclined with respect to a rotational axis direction, and a drive unit that rotates the axial-flow impeller. The housing includes a mount portion and a sidewall. To the mount portion, the drive unit is mounted. The sidewall is provided around the axial-flow impeller, and has a plurality of slits that circulate gas. The plurality of slits are inclined with respect to the rotational axis direction in a direction opposed to a direction in which the plurality of blades incline.
According to another embodiment of the present invention, there is provided an electronic apparatus including a casing and an axial fan apparatus. The axial fan apparatus includes an axial-flow impeller, a drive unit, and a housing. The axial-flow impeller is capable of rotating and includes a plurality of blades inclined with respect to a rotational axis direction. The drive unit rotates the axial-flow impeller. The housing is mounted with the drive unit and disposed in the casing, and includes a sidewall, and a plurality of slits that circulate gas. The sidewall is provided around the axial-flow impeller. The plurality of slits are provided to the sidewall and inclined with respect to the rotational axis direction in a direction opposed to a direction in which the plurality of blades incline.
As described above, according to the embodiments of the present invention, noise can be suppressed and flow rate can be increased.
These and other objects, features and advantages of the present invention will become more apparent in light of the following detailed description of best mode embodiments thereof, as illustrated in the accompanying drawings.
In the following, embodiments of the present invention will be described with reference to the accompanying drawings.
The axial fan apparatus 10 includes a housing 3 and an axial-flow impeller 5. The axial-flow impeller 5 is capable of rotating inside the housing 3. The axial-flow impeller 5 includes a boss unit 6 and a plurality of blades 7. A motor (drive unit; not shown) is built in the boss unit 6. The plurality of blades 7 are provided around the boss unit 6.
The housing 3 includes an annular sidewall 35. An opening at an upper portion of the sidewall 35 serves as a suction port 3a. Airflows in an axial direction (Z direction) generated by the blades 7 rotating in a θ direction are sucked into the housing 3 via the suction port 3a. As shown in
As shown in
The sidewall 35 of the housing 3 is provided with a plurality of slits 35a via which the gas is circulated. As shown in
The slits 35a are provided by predetermined pitches in a rotational circumferential direction (θ direction) of the axial-flow impeller 5. The pitch can arbitrarily be set. The pitch may be set depending on a width u of the slit 35a and a diameter R (refer to
The blade 7 includes a negative pressure generation surface 7a at the suction port 3a side, and a back surface 7b opposed to the negative pressure generation surface 7a. The negative pressure generation surface 7a generates laminar flows of the gas, to thereby generate a negative pressure, and is curved. So, in a precise sense, the inclination of the blade 7 refers to an inclination of a tangent line at a given point on the curved negative pressure generation surface 7a, specifically, an inclination of the tangent line in the rotational circumferential direction of the axial-flow impeller 5 with respect to the rotational axis direction. Alternatively, the inclination of the blade 7 may be an average inclination of a plurality of tangent lines.
Meanwhile, the inclination of the slit 35a with respect to the rotational axis direction refers to an inclination α of the slit 35a in a longitudinal direction with respect to the rotational axis direction. The inclination α of the slit 35a is an inclination from bottom right to top left. The inclination α of the slit 35a is opposed to the inclination of the blade 7 closest to the slit 35a with respect to the rotational axis direction. The inclination α of the slit 35a with respect to the rotational axis direction is larger than 0° and smaller than 90°. The inclination α is typically 30° to 60°, specifically, 45°.
The axial-flow impeller 5 is typically made of a resin, but may be made of metal, rubber, or the like. The housing 3 is also typically made of a resin, but may be made of other materials.
Functions of the axial fan apparatus 10 structured as described above will be described.
The driving of the motor causes the axial-flow impeller 5 to rotate. The rotational direction of the blades 7 is counterclockwise seen from the top surface side of
As shown in
In addition, according to this embodiment, as shown in
(1) Axial fan apparatus A
(2) Axial fan apparatus B
(3) Axial fan apparatus C
It should be noted that, in each of the axial fan apparatus A, B, and C, the diameter of the axial-flow impeller is smaller by 0.5 to 2 mm than the diameter of the sidewall, or, in the item (3), than the length of one side of the sidewall 135 of the housing 103.
Generally, the axial fan apparatuses operate with flow rate of ±(10 to 20)% with half the maximum flow rate as a standard (hereinafter referred to as “operating point range”). To be specific, an intersection point of the P-Q curve and a system impedance curve (not shown) may, in most cases, be an operating point (e.g., 0.95). In the graph, the flow rate of the three axial fan apparatuses A, B, and C is, for example, 0.06 to 0.10 m3/min in the operating point range.
In the operating point range, the axial fan apparatus A of this embodiment represents the highest static pressure. That is, in the operating point range, the flow rate of the axial fan apparatus A (10) is larger than those of the axial fan apparatuses B and C when it is assumed that those axial fan apparatuses represent the same static pressure. In addition, in the operating point range, the noise level of the axial fan apparatus A is the lowest, and that of the general axial fan apparatus C in the past is the highest of the three. The noise level of the axial fan apparatus A is lower by 9 to 10 dB than that of the axial fan apparatus C.
It should be noted that
In the axial fan apparatus of this embodiment, denoted by reference numeral 20, each blade 17 of an axial-flow impeller 15 is provided with an auxiliary vane 18. The auxiliary vane 18 stands on a negative pressure generation surface 17a at an end portion 17c (refer to
Further, the housing 3 has the same structure as that of the housing 3 of the above embodiment. The sidewall 35 includes the slits 35a. The inclination of the slits 35a is opposed to an inclination of the blades 17.
Since each blade 17 includes the auxiliary vane 18 as described above, the swirling flows C are straightened. For example, as shown in
The height of the auxiliary vane 18 from the negative pressure generation surface 17a (height of a portion of the auxiliary vane 18 from the negative pressure generation surface 17a, the portion being most distant from the negative pressure generation surface 17a) is not limited as long as the auxiliary vane 18 does not contact the other members. Specifically, in the case that the height of the auxiliary vane 18 is smaller than twice the thickness of the blade 17 from the negative pressure generation surface 17a, the noise level can further be decreased, which will be described below.
The graph of
As shown in
As shown in
In view of the above, the height of the auxiliary vane 18 from the negative pressure generation surface 17a is preferably smaller than twice the thickness of the blade 17. With this structure, the swirling flows C are straightened owing to the slit 35a and suppressed owing to the auxiliary vane 18 in a balanced manner, the flow rate is increased, and the noise level is decreased.
The PC, denoted by reference numeral 50, includes a casing 63. The axial fan apparatus 10 (20) is arranged inside the casing 63. The axial fan apparatus 10 (20) is mounted to, for example, an opening portion (not shown) provided to a back surface 63a of the casing 63. Alternatively, the axial fan apparatus 10 (20) is mounted to, for example, a heat sink 57 connected to a CPU 55.
The electronic apparatus is not limited to a desktop PC as in the case of the PC 50, but may be a server computer, a display apparatus, an AV device, a projector, a game device, a car navigation device, or other electronic products.
Embodiments of the present invention are not limited to the embodiments as described above, but may be other various embodiments.
For example, in the axial fan apparatus 10, 20 according to the embodiments of the present invention, the slits 35a are provided to the substantially entire circumference of the sidewall in the circumferential direction. However, the plurality of slits 35a may be provided to a part of the sidewall corresponding to a predetermined angle in the circumferential direction. Alternatively, two groups of the slits 35a by the predetermined angle in the circumferential direction may be 180°-symmetrically provided to the sidewall. Alternatively, three groups of the slits 35a by the predetermined angle in the circumferential direction may be 120°-symmetrically provided to the sidewall. As described above, the slits 35a can be provided in a various manner.
It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and alternations may occur depending on design requirements and other factors insofar as they are within the scope of the appended claims or the equivalents thereof.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2007-107749 | Apr 2007 | JP | national |
This application is a continuation of U.S. patent application Ser. No. 12/101,558, filed Apr. 11, 2008, the entirety of which is incorporated herein by reference to the extent permitted by law. The present application claims priority to Japanese Patent Application No. 07-107749 filed in the Japanese Patent Office on Apr. 17, 2007, the entirety of which also is incorporated by reference herein to the extent permitted by law.
| Number | Date | Country | |
|---|---|---|---|
| Parent | 12101558 | Apr 2008 | US |
| Child | 13213691 | US |
