Cooling fan and electronic device

Abstract

Disclosed is a cooling fan (10) that includes an outer guide (23) and an inner guide (22). The outer guide (23) has a portion positioned between an upper end (21a) and a lower end (21b) of fins (21) in the axial direction and between two adjacent fins (21), and guides air toward the radial outside of an impeller (20). The inner guide (22) is positioned between the upper end (21a) and a lower end (21b) of the fins (21) in the axial direction, positioned closer to the center in the radial direction than the outer guide (23), and configured to guide the air toward the radial outside of the impeller (20). Consequently, the flow rate and flow velocity of the air delivered to the upper and lower sides of a circuit board (80) can be made appropriate.

Description

[Technical Field]

[0001] The present disclosure relates to a cooling fan and electronic device.[Background Art]

[0002] Cooling fans for cooling a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), and other heat-generating components mounted on a circuit board are disposed in an electronic device such as a video game console, a personal computer, and a server computer. The electronic device disclosed in PCT Patent Publication No. WO2021 / 193882 is configured such that the cooling fans are disposed along an edge of the circuit board. The circuit board is positioned between both ends (upper and lower ends) of the cooling fan as viewed in an axial direction (up-down direction). When the circuit board is positioned as described above, one cooling fan is enough to deliver air to both the upper and lower sides of the circuit board.[Summary]

[0003] When the cooling performance required for components mounted on the upper side of the circuit board is different from the cooling performance required for components mounted on the lower side, as in the case of a structure disclosed in PCT Patent Publication No. WO2021 / 193882, it is desirable that the flow rate and flow velocity of the air delivered to the upper and lower sides of the circuit board be appropriately adjustable according to the components.

[0004] A cooling fan proposed according to the present disclosure includes an impeller having a plurality of fins. The plurality of fins are arranged in the direction of rotation. The fins each have a first end and a second end in an axial direction. The second end is opposite the first end. The cooling fan has an outer guide and an inner guide. The outer guide has a portion positioned between the first and second ends in the axial direction and between two adjacent fins, and guides air toward a radial outside of the impeller. Further, the inner guide is positioned between the first and second ends in the axial direction, positioned closer to a center in the radial direction than the outer guide, and configured to guide the air toward the radial outside of the impeller.

[0005] The electronic device proposed according to the present disclosure includes the cooling fan and a circuit board. The circuit board is positioned between the first and second ends in the axial direction.

[0006] The cooling fan is configured such that the outer guide and the inner guide allow for a higher degree of freedom in adjusting an airflow. As a result, the flow rate and flow velocity of the air delivered toward one side (e.g., the upper side) of the circuit board and delivered to the opposite side (e.g., the lower side) can easily be made appropriate. This makes it possible to improve the cooling performance of the cooling fan for the heat-generating components disposed on the upper and lower sides of the circuit board.[Brief Description of Drawings]

[0007] [FIG. 1] FIG. 1 is a perspective view illustrating a first example of a cooling fan proposed according to the present disclosure. [FIG. 2] FIG. 2 is a perspective view of the cooling fan depicted in FIG. 1 [FIG. 3] FIG. 3 is a bottom view of the cooling fan depicted in FIG. 1. [FIG. 4A] FIG. 4A is a cross-sectional view taken along line IVb-IVb of FIG. 3. [FIG. 4B] FIG. 4B is a diagram illustrating an example of a positional relation between an outer guide, an inner guide, and a circuit board that are depicted in FIG. 4A. [FIG. 5A] FIG. 5A is a diagram illustrating another example of the positional relation between the outer guide, the inner guide, and the circuit board. [FIG. 5B] FIG. 5B is a diagram illustrating yet another example of the positional relation between the outer guide, the inner guide, and the circuit board. [FIG. 6] FIG. 6 is a perspective view illustrating a second example of the cooling fan proposed according to the present disclosure. [FIG. 7] FIG. 7 is a bottom view of the cooling fan depicted in FIG. 6. [FIG. 8A] FIG. 8A is a cross-sectional view taken along line VIIa-VIIa of FIG. 7. [FIG. 8B] FIG. 8B is a diagram illustrating the positional relation between the outer guide, the inner guide, and the circuit board depicted in FIG. 8A. [FIG. 9] FIG. 9 is a diagram illustrating an example of an electronic device in which the cooling fan is mounted. [FIG. 10] FIG. 10 is a front view of the electronic device depicted in FIG. 9. [Description of Embodiment]

[0008] A cooling fan and electronic device proposed according to the present disclosure will now be described. The present disclosure describes, as examples, the cooling fan 10 (see FIG. 1), the cooling fan 110 (see FIG. 6), and the electronic device 90 (see FIG. 9).

[0009] In the following description, directions indicated by Z1 and Z2, for example, in FIG. 1 will be referred to as an upward direction and a downward direction, respectively. Further, directions indicated by X1 and X2 in FIG. 9, which depicts the electronic device 90, will be referred to as a rightward direction and a leftward direction, respectively, and directions indicated by Y1 and Y2 will be referred to as a forward direction and a rearward direction, respectively. These directions are defined to explain a relative positional relation between the elements (parts, members, and sections) of the electronic device 90. Therefore, the directions indicated in the drawings do not limit postures of the cooling fans 10 and 110 and electronic device 90 during their use.[Overview of Cooling Fan]

[0010] First, the cooling fan 10 will be described as a first example. As depicted in FIG. 1, the cooling fan 10 includes an impeller 20. The impeller 20 is rotatable around an axis line C1 that runs in the up-down direction. The impeller 20 has a plurality of fins 21 that are arranged in the direction in which the impeller 20 rotates.

[0011] As depicted in FIG. 4A, the cooling fan 10 has an electric motor 60 at its center. The electric motor 60 includes a stator 62 and a rotor 61. The rotor 61 surrounds the stator 62. Further, the cooling fan 10 has a motor housing 30 that houses the electric motor 60. The motor housing 30 has a cylindrical section 30a and a bottom section 30b. The bottom section 30b is positioned at the lower end of the cylindrical section 30a. The rotor 61 of the electric motor 60 is secured to the cylindrical section 30a. The impeller 20 is secured to the motor housing 30, and rotates when driven by the electric motor 60. The impeller 20 and the motor housing 30 may be integrally molded from resin.

[0012] As depicted in FIG. 3, the fins 21 have a plate-like shape formed in an axial direction and extend toward a radial outside of the impeller 20. When the impeller 20 rotates, air is introduced into the impeller 20 from the upper and lower sides of the impeller 20, and delivered to the radial outside of the impeller 20. The fins 21 may extend, for example, obliquely in two directions, namely, in the radial direction and rotation direction of the impeller 20. Further, the fins 21 may be curved along a part of a clothoid curve. The curved shape of the fins 21 is capable of increasing efficiency of air introduction and delivery by the cooling fan 10. An end of each fin 21 (the end close to a center in the radial direction) may be secured to the cylindrical section 30a of the motor housing 30. Alternatively, the end of each fin 21 (the end close to the center in the radial direction) may be connected to an outer edge 22b of an inner guide 22 that is annular in shape and described later.

[0013] As depicted in FIG. 2, the cooling fan 10 includes a base plate 40. The base plate 40 has an outer peripheral base section 41 and a central base section 42. The outer peripheral base section 41 is annular in shape. The central base section 42 is formed inside the outer peripheral base section 41, and intersects with the axis line C1 of the cooling fan 10. The outer peripheral base section 41 has a plurality of mounting sections 41a that protrude radially outward. When the impeller 20 rotates, the air is introduced into the impeller 20 through an opening between the central base section 42 and the outer peripheral base section 41.

[0014] The base plate 40 is disposed, for example, on one side in the axial direction of the impeller 20 (the upper side in the depicted example). As depicted in FIG. 4A, the cooling fan 10 includes a support section 50 for supporting the electric motor 60. The support section 50 has a motor support section 52 that is positioned inside the motor housing 30 to support the stator 62. The support section 50 has a secured section 51. The secured section 51 is disposed on the upper end of the support section 50 and secured to the central base section 42. The secured section 51 and the motor support section 52 may be coupled to each other, for example, through a through-hole formed in the central base section 42. The secured section 51 and the motor support section 52 may be integrally molded from resin.

[0015] As depicted in FIG. 4A, the central base section 42 of the base plate 40 is positioned above the outer peripheral base section 41. This makes it possible to raise the position of the electric motor 60 and the position of the motor housing 30, which houses the electric motor 60. This increases an amount of air that is introduced into the impeller 20 from below the cooling fan 10.

[0016] In a situation where the cooling fan 10 is mounted in the electronic device 90, the cooling fan 10 may be disposed in a posture in which the base plate 40 is positioned above the impeller 20, or conversely, positioned below the impeller 20.

[0017] The electronic device 90 includes a circuit board 80 (see FIG. 10). As depicted in FIG. 4A, the cooling fan 10 mounted in the electronic device 90 is disposed along an edge of the circuit board 80. The position of the circuit board 80 in the axial direction of the cooling fan 10 (the up-down direction (Z1-Z2 direction) in the depicted example) is between the upper end 21a and the lower end 21b of the fins 21. When the impeller 20 rotates, a part of an airflow flows along an upper surface 80a of the circuit board 80, and another part of the airflow flows along a lower surface 80b of the circuit board 80. This allows the one cooling fan 10 to cool both components (cooling targets) disposed on the upper side of the circuit board 80 and components (cooling targets) disposed on the lower side of the circuit board 80.

[0018] In an example of the electronic device 90, the components generating more heat than the components on the upper side of the circuit board 80 are mounted on the lower surface 80b of the circuit board 80. Therefore, as will be described in detail later, the impeller 20 and the circuit board 80 are disposed and configured in such a manner as to supply more air to the lower surface 80b of the circuit board 80 than to the upper surface 80a. The components generating a large amount of heat, for example, integrated circuits, such as a CPU, a GPU, and a memory, or an SoC (System on a Chip) having the functions of such integrated circuits may be disposed on the lower surface 80b of the circuit board 80.[Inner Guide and Outer Guide]

[0019] As depicted in FIG. 4A, the impeller 20 includes an outer guide 23. The outer guide 23 is positioned between the upper end 21a and lower end 21b of the fins 21 in the axial direction (Z1-Z2) of the cooling fan 10. Stated differently, the outer guide 23 is positioned downwardly away from the upper end 21a and upwardly away from the lower end 21b. The outer guide 23 may be displaced, for example, in the axial direction from a horizontal plane H4 (see FIG. 4B; the plane perpendicular to the axial direction) that passes midway between the upper end 21a and lower end 21b of the fins 21.

[0020] The outer guide 23 has a portion that is positioned between two adjacent fins 21. As depicted in FIG. 3, the outer guide 23 has, for example, an annular shape surrounding the entire periphery of the motor housing 30, and couples all of the fins 21. (The outer guide 23 is also shaded in FIG. 3.) Therefore, a part of the outer guide 23 is formed between any two adjacent fins 21.

[0021] As depicted in FIG. 4A, the impeller 20 includes the inner guide 22. The inner guide 22 is positioned between the upper end 21a and lower end 21b of the fins 21 in the axial direction (Z1-Z2). Stated differently, the inner guide 22 is positioned downwardly away from the upper end 21a and upwardly away from the lower end 21b. Further, the inner guide 22 is positioned closer to the center (axis line C1) in the radial direction than the outer guide 23.

[0022] Furthermore, the inner guide 22 may have a portion that is positioned between two adjacent fins 21. As depicted in FIG. 3, the inner guide 22 has, for example, an annular shape surrounding the entire periphery of the motor housing 30, and couples all of the fins 21. (The inner guide 22 is shaded in FIG. 3.) Therefore, a part of the inner guide 22 may be formed between any two adjacent fins 21. An inner edge 22c (the end close to the axis line C1) of the inner guide 22 may be connected to the outer peripheral surface of the motor housing 30. It should be noted that the ends of the fins 21 positioned close to the axis line C1 need not necessarily be connected to the outer peripheral surface of the motor housing 30. In such a case, the inner edge 22c of the inner guide 22 may be connected to the outer peripheral surface of the motor housing 30, and the ends of the fins 21 positioned close to the axis line C1 may be connected only to the inner guide 22.

[0023] As depicted in FIG. 4B, the fins 21 have an inner region portion 21e whose axial width gradually increases toward the outside in the radial direction. The inner guide 22 is positioned between the upper and lower edges of the inner region portion 21e. The inner guide 22 may be disposed so as to intersect, for example, with the horizontal plane H4 (the plane perpendicular to the axial direction) that passes midway between the upper end 21a and lower end 21b of the fins 21.

[0024] As depicted in FIG. 4B, when the impeller 20 is cross-sectionally viewed in the axial direction, the inner and outer guides 22 and 23 may be plate-shaped. That is, widths W2 and W3 of the inner and outer guides 22 and 23 may be greater than thicknesses T2 and T3 thereof.

[0025] The inner guide 22 and the outer guide 23 guide the air, which flows into the impeller 20 from above and below, outward in the radial direction. For example, an airflow F1 (see FIG. 4A), an airflow F2 (see FIG. 4A), and an airflow F3 (see FIG. 4A) are formed. The airflow F1 is guided by an upper surface 23a (see FIG. 4B) of the outer guide 23, and delivered toward the outside in the radial direction. The airflow F2 is formed between the outer guide 23 and the inner guide 22. The airflow F3 is guided by a lower surface of the outer guide 23 and a lower surface 22a (see FIG. 4B) of the inner guide 22, and delivered toward the outside in the radial direction.

[0026] The impeller 20 has the two guides 22 and 23 as described above, and thus allows for a higher degree of freedom in adjusting the airflow. As a result, the airflow formed along the upper surface 80a of the circuit board 80 and the airflow formed along the lower surface 80b can easily be made appropriate. In the example depicted, for example, in FIG. 4A, it is possible to not only obtain a sufficient flow rate and flow velocity of the air to be delivered to the lower side of the circuit board 80 but also obtain a required flow rate and flow velocity of the air to be delivered to the upper side of the circuit board 80. This improves the cooling performance of the cooling fan 10 for the heat-generating components disposed on the upper and lower sides of the circuit board 80. This makes it possible to effectively cool the heat-generating components while reducing the noise generated when the cooling fan 10 is driven.

[0027] As depicted in FIG. 4B, the outer edge 22b of the inner guide 22 is positioned inside an inner edge 23b of the outer guide 23 (positioned close to the axis line C1). Therefore, when the cooling fan 10 is viewed in the axial direction, the inner guide 22 and the outer guide 23 do not overlap. This makes it possible to smooth the airflow passing between the inner guide 22 and the outer guide 23. In addition, this makes it easy to mold the impeller 20 from resin.[Positional Relation between Outer Guide and Inner Guide in Axial Direction]

[0028] A height of the inner guide 22 and a height of the outer guide 23, that is, their positions in the axial direction, will now be described. As depicted in FIG. 4B, the outer edge 22b of the inner guide 22 and the inner edge 23b of the outer guide 23 are positioned away from each other in the axial direction (up-down direction). This makes it possible to increase a width of an airflow path between the inner edge 23b of the outer guide 23 and the outer edge 22b of the inner guide 22. In the example depicted in FIG. 4B, the inner edge 23b of the outer guide 23 is positioned higher than the outer edge 22b of the inner guide 22.

[0029] Further, as depicted in FIG. 4B, the position of the inner edge 23b of the outer guide 23 (the position in the axial direction) is different from the position of the inner edge 22c of the inner guide 22 (the position in the axial direction). This makes it possible to increase the degree of freedom in the width of the airflow path formed between the two guides 22 and 23. For example, the width of the airflow path formed between the two guides 22 and 23 can be increased or decreased. In the example depicted in FIG. 4B, the inner edge 23b of the outer guide 23 is positioned higher than the inner edge 22c of the inner guide 22. This results in an increase in the width of the airflow path formed between the two guides 22 and 23.

[0030] Furthermore, as depicted in FIG. 4B, the outer edge 22b and inner edge 22c of the inner guide 22 may be shifted to one side in the axial direction with respect to the outer edge 23c and inner edge 23b of the outer guide 23. That is, the inner guide 22 may be entirely positioned on one side in the axial direction of a horizontal plane H1 (see FIG. 4B) (positioned below in the example of FIG. 4B), and the outer guide 23 may be entirely positioned on the side opposite the inner guide 22 with respect to the horizontal plane H1 (positioned above in the example of FIG. 4B). This makes it possible to further expand the width of the airflow path between the inner guide 22 and the outer guide 23, and increase the amount of air that is passed between the two guides 22 and 23 and delivered to the lower side of the circuit board 80.[Inclination of Guides]

[0031] As depicted in FIG. 4B, the inner guide 22 may be inclined in such a manner that the height of its outer edge 22b (the position in the axial direction) is different from the height of its inner edge 22c. This allows the inner guide 22 to adjust the direction of the airflow from the impeller 20. In the example depicted in FIG. 4B, the inner guide 22 is inclined in such a manner that the outer edge 22b is lower in height than the inner edge 22c. This allows the air to be delivered to the lower side of the circuit board 80.

[0032] The outer guide 23 may also be inclined in such a manner that the height of its outer edge 23c (the position in the axial direction) is different from the height of its inner edge 23b. This allows the outer guide 23 to adjust the direction of the airflow from the impeller 20. In the example depicted in FIG. 4B, the outer guide 23 is inclined in such a manner that the outer edge 23c is lower in height than the inner edge 23b.

[0033] As described above, the two guides 22 and 23 are inclined in the same direction in the example depicted in FIG. 4B. Since the guides 22 and 23 are shaped in a manner described above, it is possible to smooth the airflow passing between the two guides 22 and 23. In the depicted example, the outer edges 22b and 23c of the inner guide 22 and outer guide 23 are both lower in height than the inner edges 22c and 23b. This makes it possible to smooth the airflow that is passed between the two guides 22 and 23 and directed toward the lower side of the circuit board 80.[Curvature of Guides]

[0034] Further, when the impeller 20 is cross-sectionally viewed in the axial direction, at least one of the guides 22 and 23 may be curved.

[0035] As depicted, for example, in FIG. 4B, the outer guide 23 may be curved so as to bulge downward. That is, the outer guide 23 may be curved along a virtual arc that is formed around a center located above the outer guide 23. This curvature makes it possible to increase the amount of air that runs from the upper side of the impeller 20 and flows in between the two guides 22 and 23. It should be noted that, unlike FIG. 4B, the outer guide 23 need not necessarily have the above-described curvature.

[0036] Furthermore, as depicted in FIG. 4B, the inner guide 22 may be curved so as to bulge upward. That is, the inner guide 22 may be curved along a virtual arc that is formed around a center located below the inner guide 22. This curvature makes it possible to increase the amount of air that runs from the upper side of the impeller 20 and flows in between the two guides 22 and 23. It should be noted that, unlike FIG. 4B, the inner guide 22 need not necessarily have the above-described curvature.[Positional Relation between Circuit Board and Guides]

[0037] As depicted in FIG. 4B, the circuit board 80 may be disposed, for example, above the horizontal plane H4, which passes midway between the upper end 21a and lower end 21b of the fins 21. The inner guide 22 may be positioned below the circuit board 80. More specifically, the inner edge 22c and outer edge 22b of the inner guide 22 may be both positioned below the circuit board 80. As a result, the air flowing into the impeller 20 from below and hitting the inner guide 22 and the air flowing into the impeller 20 from above and hitting the inner guide 22 (the air passing between the two guides 22 and 23) are directed toward the lower side of the circuit board 80.

[0038] As described above, the outer guide 23 is positioned above the inner guide 22. The outer guide 23 is capable of increasing the airflow along the upper surface 80a of the circuit board 80. For example, the air introduced into the impeller 20 from above hits the upper surface 23a of the outer guide 23. Then, a part of that air is guided to the upper side of the upper surface 80a of the circuit board 80. As depicted in FIG. 4B, the outer guide 23 may be positioned slightly below the circuit board 80. More specifically, the inner edge 23b of the outer guide 23 may be positioned at substantially the same height as the circuit board 80, and the outer edge 23c of the outer guide 23 may be positioned below the circuit board 80. In FIG. 4B, a horizontal plane H5 (the plane perpendicular to the axial direction) passing through the circuit board 80 passes through the inner edge 23b of the outer guide 23.

[0039] Research by the present inventors has revealed that the flow velocity of the air delivered from the impeller 20 varies with the height (the position in the axial direction) and becomes higher at the height of the guides 22 and 23. As described above, the inner guide 22 is positioned below the circuit board 80, and thus contributes to improving the flow rate and flow velocity of the airflow along the lower surface 80b of the circuit board 80.

[0040] As depicted in FIG. 4B, the inner edge 23b of the outer guide 23 is positioned at substantially the same height as the circuit board 80 while the outer guide 23 is positioned higher than the inner guide 22. Positioning the outer guide 23 in the above manner contributes to improving the flow rate and flow velocity of the airflow along the upper surface 80a of the circuit board 80.

[0041] Further, as depicted in FIG. 4B, the outer edge 23c of the outer guide 23 is positioned slightly below the circuit board 80. The outer guide 23 positioned in the above manner and the inner guide 22 collaborate to additionally contribute toward the improvement of the flow velocity of the airflow along the lower surface 80b of the circuit board 80.

[0042] As depicted in FIG. 4B, the outer edge 22b of the inner guide 22 and the outer edge 23c of the outer guide 23 are both positioned below the horizontal plane H5 including the circuit board 80. This allows the air passing between the inner guide 22 and the outer guide 23 to be supplied to the lower side of the circuit board 80. Moreover, as depicted in FIG. 4, the inner edge 23b of the outer guide 23 may be at substantially the same position as a plane including the circuit board 80.

[0043] As depicted in FIG. 4B, the outer edge 23c of the outer guide 23 is positioned radially inward from outer ends 21c of the fins 21. When the outer guide 23 is positioned in the above manner, an airflow path from the upper side of the outer guide 23 to the lower side of the circuit board 80 can be provided between the circuit board 80 and the outer edge 23c of the outer guide 23.

[0044] It should be noted that a positional relation between the guides 22 and 23 and the circuit board 80 is not limited to the example depicted, for instance, in FIG. 4B. The outer guide 23 may be, for example, positioned partially above the circuit board 80. For example, the outer edge 23c of the outer guide 23 may be positioned below the circuit board 80 while the inner edge 23b of the outer guide 23 is positioned above the circuit board 80. As another example, the outer guide 23 may be positioned entirely above the circuit board 80. That is, the inner edge 23b and outer edge 23c of the outer guide 23 may be both positioned above the circuit board 80.[Alternative Guide Positions]

[0045] The positional relation between the two guides 22 and 23 is not limited to the example depicted, for instance, in FIG. 4B.

[0046] For example, although the inner edge 22c of the inner guide 22 is positioned higher than the inner edge 23b of the outer guide 23 as depicted in FIG. 5A, the outer edge 22b of the inner guide 22 may be positioned lower than the inner edge 23b of the outer guide 23.

[0047] Further, the guides 22 and 23 need not necessarily be inclined. In the example of FIG. 5A, the outer guide 23 is formed in parallel with a horizontal plane H2 that is perpendicular to the axial direction.

[0048] As yet another example, the height of the inner edge 22c of the inner guide 22 (the position in the axial direction) and the height of the inner edge 23b of the outer guide 23 may be equal as depicted in FIG. 5B. That is, a horizontal plane H3 perpendicular to the axial direction may pass through both the inner edge 22c of the inner guide 22 and the inner edge 23b of the outer guide 23. In such a case, the outer edge 23c of the outer guide 23 may be positioned higher than the outer edge 22b of the inner guide 22.[Radial Positional Relation between Elements]

[0049] As depicted in FIG. 4B, the fins 21 have the inner region portion 21e and an outer region portion 21f. The inner region portion 21e is a portion where the width of the fins 21 in the axial direction gradually increases toward the outside in the radial direction. The outer region portion 21f is a portion where the width of the fins 21 in the axial direction is substantially constant in the radial direction. The outer peripheral base section 41 (see FIG. 4A) of the base plate 40 is positioned above the outer region portion 21f. The inner region portion 21e is positioned inside the outer peripheral base section 41 of the base plate 40.

[0050] The radial position of an inner edge 41b (see FIG. 4A) of the outer peripheral base section 41 may substantially correspond to the position of a boundary between the outer region portion 21f and the inner region portion 21e.

[0051] The outer guide 23 may be positioned partially inside of the inner edge 41b of the outer peripheral base section 41 of the base plate 40. Specifically, as depicted in FIGS. 3 and 4A, the inner edge 23b (see FIG. 3) of the outer guide 23 may be positioned inside the inner edge 41b (see FIG. 3) of the outer peripheral base section 41. When the outer guide 23 is positioned in the above manner, the air delivered from the upper side of the cooling fan 10, passed through the opening in the base plate 40, and introduced into the impeller 20 can be more effectively guided radially outward by the outer guide 23.

[0052] As depicted in FIG. 4A, the base plate 40, the outer guide 23, and the inner guide 22 are arranged in this order in the axial direction. Specifically, the outer guide 23 is positioned below the base plate 40, and the inner guide 22 is positioned below the outer guide 23. When the guides 22 and 23 and the base plate 40 are positioned in the above manner, the air having passed inside the inner edge 41b of the outer peripheral base section 41 of the base plate 40 can be captured by the outer guide 23 and guided radially outward. Additionally, the air having passed inside the inner edge 41b of the outer peripheral base section 41 can be captured by the inner guide 22 and guided radially outward.

[0053] Meanwhile, the outer edge 23c (see FIG. 3) of the outer guide 23 is positioned radially outward from the inner edge 41b of the outer peripheral base section 41. Therefore, when the cooling fan 10 is viewed in the axial direction, the outer portion of the outer guide 23 overlaps with the outer peripheral base section 41 of the base plate 40 as depicted in FIG. 3. The research by the present inventors has revealed that the outer guide 23 positioned in the above manner is capable of reducing the noise generated when the cooling fan 10 is driven.

[0054] As depicted in FIG. 4B, a portion of the outer guide 23 (the portion close to the axis line C1) is connected to the inner region portion 21e of the fins 21, and the remaining portion of the outer guide 23 (the portion farther from the axis line C1) is connected to the outer region portion 21f. When the outer guide 23 is positioned in the above manner, the air introduced into the impeller 20 from the upper side of the cooling fan 10 can be more effectively guided radially outward by the outer guide 23. The inner guide 22 is formed on the inner region portion 21e.

[0055] As depicted in FIG. 1, the impeller 20 includes a reinforcing ring 24. The reinforcing ring 24 couples the ends of the fins 21. Consequently, the impeller 20 is reinforced. For example, it is possible to prevent the fins 21 from bending when the impeller 20 rotates. In the example depicted, for instance, in FIG. 1, the reinforcing ring 24 is secured to the lower end 21b of the fins 21. However, the reinforcing ring 24 may alternatively be secured to the ends 21c of the fin 21 in the radial direction.

[0056] As depicted in FIG. 3, the outer guide 23 is positioned inside the reinforcing ring 24. More specifically, the outer edge 23c of the outer guide 23 is positioned inward from an inner edge 24a of the reinforcing ring 24. Therefore, when the cooling fan 10 is viewed in the axial direction, the outer guide 23 and the reinforcing ring 24 do not overlap. This makes it easy to mold the impeller 20 from resin.[Second Example of Cooling Fan]

[0057] The cooling fan 110, that is, a second example of the cooling fan proposed according to the present disclosure, will now be described with reference to FIGS. 6 to 8B. The following description of the cooling fan 110 focuses on the differences between the cooling fan 110 and the earlier-described cooling fan 10. The matters not described in regard to the cooling fan 110 may be considered similar to those described in regard to the cooling fan 10.

[0058] The cooling fan 110 includes an impeller 120 having a plurality of fins 121 that are arranged in the rotation direction. As depicted in FIG. 8B, the fins 121 each have an inner region portion 121a and an outer region portion 121b. As is the case with the cooling fan 10, the inner region portion 121a is a portion where the width of the fins 121 in the axial direction gradually increases toward the outside in the radial direction. The outer region portion 121b is a portion where the width of the fins 121 in the axial direction is substantially constant in the radial direction. The outer peripheral base section 41 of the base plate 40 (see FIG. 8A) is positioned above the outer region portion 21f. The inner region portion 21e is positioned inward from the outer peripheral base section 41 of the base plate 40.

[0059] As depicted in FIG. 8B, recesses 121c and 121d are formed on the edge of the inner region portion 121a. The recess 121c is formed on the upper edge of the inner region portion 121a. The recess 121d is formed on the lower edge of the inner region portion 121a. The recesses 121c and 121d are capable of reducing the air resistance encountered by the fins 121 when the impeller 120 rotates. This makes it possible to reduce the noise generated by the rotation of the impeller 120.

[0060] As depicted in FIGS. 8A and 8B, the impeller 120 has the inner guide 22 and the outer guide 23, as is the case with the earlier-described impeller 20. The inner guide 22 is connected to the inner region portion 121a. The inner region portion 121a has a portion positioned above the inner guide 22 and a portion positioned below the inner guide 22. A portion of the outer guide 23 is positioned on the inner region portion 121a, and the remaining portion is positioned on the outer region portion 121b.[Electronic Device]

[0061] The electronic device 90 in which the cooling fan 10 or the cooling fan 110 is mounted will now be described. The electronic device 90 is, for example, an entertainment device that functions as a video game console or audio-visual device. The electronic device 90 outputs video image data generated when a game program is executed, video / audio data acquired through a network, and video / audio data acquired from a recording medium, such as an optical disk, to a display device such as a television. The electronic device may be a personal computer or a server computer.

[0062] As depicted in FIG. 9, the electronic device 90 includes a device main body 91. The device main body 91 has a housing 91a. The housing 91a houses the above-described cooling fan 10. The cooling fan 10 is disposed in such a manner that the axis line C1 passing through the center of rotation of the cooling fan 10 faces in the up-down direction (Z1-Z2 direction) of the electronic device 90. The housing 91a additionally houses a circuit board on which various electronic components, such as a CPU and a GPU, are mounted. The housing 91a has a radiator (e.g., a heat sink or a heat pipe). The radiator is connected to the electronic components such as a CPU. The cooling fan 10 introduces outside air into the housing 91a to form an airflow that passes through the radiator.

[0063] The electronic device 90 has an upper exterior panel 92 that covers an upper surface of the housing 91a. The electronic device 90 additionally has a lower exterior panel 93 that covers a lower surface of the housing 91a. As depicted in FIG. 9, the exterior members of the electronic device 90 (i.e., the upper exterior panel 92, the lower exterior panel 93, and the housing 91a) have air intake ports Sa, Sb, Sc, and Sd for introducing the outside air into the interior of the electronic device 90.

[0064] As depicted in FIG. 10, the air is introduced from the upper air intake ports Sa and Sb when the cooling fan 10 is driven. The introduced air flows between the upper surface of the housing 91a and the upper exterior panel 92, and is introduced into the cooling fan 10 from above. Further, when the cooling fan 10 is driven, the air is introduced from the lower air intake ports Sc and Sd. The air introduced in this manner flows between the lower surface of the housing 91a and the lower exterior panel 93, and is introduced into the cooling fan 10 from below.

[0065] As depicted in FIG. 10, the cooling fan 10 within the housing 91a is disposed on the edge of the circuit board 80. The air introduced into the cooling fan 10 is delivered radially outward by the rotation of the impeller 20 to form airflows above and below the circuit board 80.[Outline]

[0066] (1) The cooling fan proposed according to the present disclosure includes an impeller having a plurality of fins. The plurality of fins are arranged in the direction of rotation. The fins each have a first end and a second end in the axial direction. The second end is opposite the first end. The cooling fan additionally has an outer guide and an inner guide. The outer guide has a portion positioned between the first and second ends in the axial direction and between two adjacent fins, and guides air toward the radial outside of the impeller. The inner guide is positioned between the first and second ends in the axial direction, positioned closer to the center in the radial direction than the outer guide, and configured to guide the air toward the radial outside of the impeller. The cooling fan has the two guides, and is thus capable of increasing the degree of freedom in adjusting an airflow. As a result, the flow rate and flow velocity of the air delivered toward one side (e.g., the upper side) of a circuit board and delivered to the opposite side (e.g., the lower side) can easily be made appropriate. This makes it possible to improve the cooling performance of the cooling fan for heat-generating components disposed on the upper and lower sides of the circuit board. Consequently, it is possible to effectively cool the heat-generating components while reducing the noise generated when the cooling fan is driven. (2) The cooling fan described in (1) may be configured such that the outer edge and inner edge of the inner guide are different in position in the axial direction. Adopting such a configuration makes it easy to adjust the direction of the airflow. (3) The cooling fan described in (1) or (2) may be configured such that the outer edge and inner edge of the outer guide are different in position in the axial direction. Adopting such a configuration makes it easy to adjust the direction of the airflow. (4) The cooling fan described in any one of (1) to (3) may be configured such that the outer edge of the inner guide is positioned closer to one side in the axial direction (placed in a lower position in the example depicted, for example, in FIG. 4B) than the inner edge of the inner guide, and that the outer edge of the outer guide is positioned closer to the one side in the axial direction (placed in a lower position in the example depicted, for example, in FIG. 4B) than the inner edge of the outer guide. Adopting such a configuration makes it possible to smooth the airflow passing between the above-mentioned two guides. (5) The cooling fan structured as described in any one of (1) to (4) may include a base plate that is positioned in the axial direction with respect to the impeller. The base plate may have an outer peripheral base section that is annular in shape. The outer guide may have a portion that is positioned closer to the center in the radial direction than the inner edge of the outer peripheral base section. When such a configuration is adopted, the air passing inside the outer peripheral base section can be effectively guided by the outer guide. (6) When the structure described in any one of (1) to (5) is adopted, the outer guide may have a portion that is positioned closer to the outside in the radial direction than the inner edge of the outer peripheral base section of the base plate. Adopting such a configuration makes it possible to smooth the airflow and thus reduce the noise generated when the cooling fan is driven. (7) When the structure described in any one of (1) to (6) is adopted, the base plate, the outer guide, and the inner guide may be arranged in this order in the axial direction. Adopting such a configuration makes it possible to allow the outer guide to guide the air introduced from the inside of the outer peripheral plate section of the base plate, and allow the inner guide to guide the air passing inside the outer guide. (8) The cooling fan described in any one of (1) to (7) may be configured such that the inner edge of the outer guide is positioned closer to the outside in the axial direction than the outer edge of the inner guide. Adopting such a configuration makes it possible to smooth the airflow passing between the inner guide and the outer guide, and makes it easy to mold the impeller from resin. (9) When the structure described in any one of (1) to (8) is adopted, the cooling fan may additionally include a reinforcing ring that couples the radially outer ends of the fins. Adopting such a configuration makes it possible to increase strength of the impeller. (10) The cooling fan described in (9) may be configured such that the outer edge of the outer guide is positioned closer to the center in the radial direction than the inner edge of the reinforcing ring. Adopting such a configuration makes it possible to avoid complicating an impeller molding process. (11) The cooling fan described in any one of (1) to (10) may be configured such that the outer edge of the inner guide and the inner edge of the outer guide are positioned away from each other in the axial direction. Adopting such a configuration makes it possible to provide a sufficient airflow path between the inner edge of the outer guide and the outer edge of the inner guide. (12) The cooling fan described in any one of (1) to (11) may be configured such that the inner edge of the outer guide and the inner edge of the inner guide are placed in different positions in the axial direction. Adopting such a configuration makes it possible to increase the degree of freedom in the width of the airflow path formed between the two guides. (13) The cooling fan described in any one of (1) to (12) may be configured such that the outer edge and inner edge of the inner guide are positioned closer to one side in the axial direction than the outer edge and inner edge of the outer guide, respectively. Adopting such a configuration makes it possible to further enlarge the airflow path between the outer guide and the inner guide. (14) The electronic device proposed according to the present disclosure includes the cooling fan described in any one of (1) to (13) and the circuit board positioned between the first end and the second end. (15) The electronic device described in (14) may be configured such that the outer edge of the inner guide and the outer edge of the outer guide are positioned closer to one side in the axial direction than a plane including the circuit board. Adopting such a configuration makes it possible to supply air passing between the inner guide and the outer guide to one side of the circuit board. [Others]

[0067] The cooling fan proposed according to the present disclosure is not limited to the cooling fan 10, which is described above, and various modifications may be made. Further, the electronic device proposed according to the present disclosure is not limited to the electronic device 90, which is described above, and various modifications may be made.

[0068] For example, the impeller 20 may include more than two annular guides that are arranged in the radial direction.

[0069] Moreover, the cooling fan 10 is configured such that the outer guide 23 and the inner guide 22 both have an annular shape and couple all the fins 21. However, the inner and outer guides 22 and 23 may alternatively be provided only for a portion of the rotation direction of the impeller 20. Stated differently, the impeller 20 may have two adjacent fins 21 having no inner and outer guides 22 and 23 provided between them. In the case where the inner and outer guides 22 and 23 are provided only for a portion of the rotation direction of the impeller 20 as mentioned above, the outer guide 23 is positioned in the radial direction of the inner guide 22. That is, the position (angular position) of the outer guide 23 in the rotation direction of the impeller 20 may coincide with the position of the inner guide 22 in the rotation direction of the impeller 20.

Claims

1. A cooling fan comprising: an impeller that includes a plurality of fins arranged in a direction of rotation, the fins each having a first end and a second end in an axial direction, the second end being opposite the first end; an outer guide that has a portion positioned between the first and second ends in the axial direction and between two adjacent fins and guides air toward a radial outside of the impeller; and an inner guide that is positioned between the first and second ends in the axial direction, positioned closer to a center in the radial direction than the outer guide, and configured to guide the air toward the radial outside of the impeller.

2. The cooling fan according to claim 1, wherein an outer edge and an inner edge of the outer guide are different in position in the axial direction.

3. The cooling fan according to claim 1, wherein an outer edge and an inner edge of the inner guide are different in position in the axial direction.

4. The cooling fan according to claim 1, wherein an outer edge of the inner guide is positioned closer to one side in the axial direction than an inner edge of the inner guide, and an outer edge of the outer guide is positioned closer to the one side in the axial direction than an inner edge of the outer guide.

5. The cooling fan according to claim 1, further comprising: a base plate that is positioned in the axial direction with respect to the impeller, wherein the base plate has an outer peripheral base section that is annular in shape, and the outer guide has a portion that is positioned closer to the center in the radial direction than an inner edge of the outer peripheral base section.

6. The cooling fan according to claim 1, further comprising: a base plate that is positioned in the axial direction with respect to the impeller, wherein the base plate has an outer peripheral base section that is annular in shape, and the outer guide has a portion that is positioned closer to an outside in the radial direction than an inner edge of the outer peripheral base section.

7. The cooling fan according to claim 5 or 6, wherein the base plate, the outer guide, and the inner guide are arranged in the axial direction in the order mentioned.

8. The cooling fan according to claim 1, wherein an inner edge of the outer guide is positioned closer to an outside in the axial direction than an outer edge of the inner guide.

9. The cooling fan according to claim 1, further comprising: a reinforcing ring that couples radially outer ends of the fins.

10. The cooling fan according to claim 9, wherein an outer edge of the outer guide is positioned closer to the center in the radial direction than an inner edge of the reinforcing ring.

11. The cooling fan according to claim 1, wherein an outer edge of the inner guide and an inner edge of the outer guide are positioned away from each other in the axial direction.

12. The cooling fan according to claim 1, wherein an inner edge of the inner guide and an inner edge of the outer guide are placed in different positions in the axial direction.

13. The cooling fan according to claim 1, wherein an outer edge and an inner edge of the inner guide are positioned closer to one side in the axial direction than an outer edge and an inner edge of the outer guide, respectively.

14. An electronic device comprising: a cooling fan; and a circuit board that is positioned between the first end and the second end in the axial direction, wherein the cooling fan includes an impeller that includes a plurality of fins arranged in a direction of rotation, the fins each having the first end and the second end in the axial direction, the second end being opposite the first end, an outer guide that has a portion positioned between the first and second ends in the axial direction and between two adjacent fins and guides air toward a radial outside of the impeller, and an inner guide that is positioned between the first and second ends in the axial direction, positioned closer to a center in a radial direction than the outer guide, and configured to guide the air toward the radial outside of the impeller.

15. The electronic device according to claim 14, wherein an outer edge of the inner guide and an outer edge of the outer guide are positioned closer to one side in the axial direction than a plane including the circuit board.

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