Cooling fan and electronic device

Abstract

A cooling fan (10) comprises: a plurality of main fins (21) disposed around an axis (C1); and a plurality of guide fins (22), which are disposed around the axis (C1) such that each is disposed between two main fins adjacent to each other in the circumferential direction around the axis (C1), and which are smaller in size than the main fins (21). According to this structure, the cooling performance of the cooling fan can be improved.

Description

Cooling fans and electronic devices

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

[0002] Cooling fans are arranged inside electronic devices such as game consoles, personal computers, and server computers to cool heat-generating components such as CPUs (Central Processing Units) and GPUs (Graphics Processing Units) mounted on circuit boards. In the electronic device disclosed in International Publication No. 2021 / 193882, the cooling fans are arranged with their rotational centerlines perpendicular to the circuit board. The cooling fans draw in external air from the top and bottom and send it outward in the radial direction. This air cools the CPUs and other components mounted on the circuit board.

[0003] An object of the present disclosure is to improve the cooling performance of a cooling fan for a heat-generating component.

[0004] The cooling fan proposed in this disclosure has a plurality of main fins arranged around an axis, and a plurality of guide fins arranged around the axis, each of which is positioned between two adjacent main fins in the circumferential direction around the axis and is smaller in size than the main fins.

[0005] The electronic device proposed in the present disclosure includes a circuit board and the cooling fan.

[0006] With the cooling fan and electronic device described above, the guide fins can adjust the flow of air blown outward in the radial direction by the main fins. As a result, the cooling performance of the cooling fan for heat-generating components can be improved. Furthermore, while increasing the number of fins can sometimes reduce the amount of air blown out, this disadvantage can be reduced because the size of the guide fins is smaller than the size of the main fins.

[0007] 1 is a plan view showing an example of a cooling fan proposed in the present disclosure; FIG. 2 is a cross-sectional view taken along line II-II shown in FIG. 1; This figure shows the positional relationship between the cooling fan and a circuit board; FIG. 3 is a perspective view of an impeller included in the cooling fan shown in FIG. 1; FIG. 4 is a bottom view of the impeller; FIG. 5 is a diagram showing the positional relationship between a main fin and a guide fin; FIG. 6 is a diagram showing the positional relationship between a main fin, a guide fin, an outer ring, and an inner ring in a cross section along the axis; FIG. 7 is a diagram showing an example of an electronic device equipped with a cooling fan; and FIG. 8 is a front view of the electronic device shown in FIG.

[0008] The cooling fan and electronic device proposed in this disclosure will be described below, taking a cooling fan 10 (see FIG. 1) and an electronic device 90 (see FIG. 6) as examples.

[0009] Hereinafter, the Z1 and Z2 directions shown in Figure 3 and other figures will be referred to as "upward" and "downward," respectively. Furthermore, in Figure 6, which shows the electronic device 90, the X1 and X2 directions will be referred to as "rightward" and "leftward," respectively, and the Y1 and Y2 directions will be referred to as "forward" and "backward," respectively. Furthermore, in Figures 2 and 3, C1 is the axis of the cooling fan 10 (axis of the impeller 20). These directions are defined to explain the shapes and relative positional relationships of the elements (components, members, and parts) of the cooling fan 10 and the electronic device 90. Therefore, the directions shown in the figures do not limit the orientation of the cooling fan 10 and the electronic device 90 during use.

[0010] [Overview of Cooling Fan] As shown in Figure 2, the cooling fan 10 has an impeller 20. The impeller 20 is rotatable about an axis C1 that runs along the up-down direction. The impeller 20 has a plurality of main fins 21 that are aligned in the rotational direction. The impeller 20 also has a plurality of guide fins 22 that are aligned in the rotational direction. Each guide fin 22 is formed between two adjacent main fins 21. The two types of fins 21 and 22 will be described in detail later.

[0011] As shown in Figure 2, the cooling fan 10 has an electric motor 60 at its center. The electric motor 60 has a stator 62 and a rotor 61 surrounding the stator 62. The cooling fan 10 also has a motor housing 30 that houses the electric motor 60. The motor housing 30 has a cylindrical portion 30a and a bottom portion 30b located at the lower end of the cylindrical portion 30a. The rotor 61 of the electric motor 60 is fixed to the cylindrical portion 30a. The impeller 20 is fixed 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] 1, the cooling fan 10 has a base plate 40. The base plate 40 has an annular outer peripheral base portion 41 and a central base portion 42 formed inside the outer peripheral base portion 41 and intersecting with the axis C1 of the cooling fan 10. The outer peripheral base portion 41 has a plurality of mounting portions 41a that protrude radially outward.

[0013] The base plate 40 is disposed, for example, on one side in the axial direction of the impeller 20 (upper side in the illustrated example). As shown in Fig. 2, the cooling fan 10 has a support portion 50 for supporting the electric motor 60. The support portion 50 has a motor support portion 52 that is located inside the motor housing 30 and supports the stator 62. The support portion 50 has a fixing portion 51 at its upper end that is fixed to the central base portion 42. The fixing portion 51 and the motor support portion 52 are formed of resin.

[0014] When the cooling fan 10 is mounted on the electronic device 90, the base plate 40 may be positioned above the impeller 20, or conversely, the base plate 40 may be positioned below the impeller 20.

[0015] The electronic device 90 has a circuit board 80 (see FIG. 6). As shown in FIG. 2, the cooling fan 10 is disposed along the edge of the circuit board 80 when mounted on the electronic device 90. The position of the circuit board 80 in the axial direction (the Z1-Z2 direction in the illustrated example) is between the upper end 21e and the lower end 21f of the main fin 21. When the impeller 20 rotates, part of the airflow (reference symbol F24 in FIG. 2) flows along the upper surface 80a of the circuit board 80, and another part of the airflow (reference symbol F12 in FIG. 2) flows along the lower surface 80b of the circuit board 80. This allows both components (cooling targets) arranged above the circuit board 80 and components (cooling targets) arranged below the circuit board 80 to be cooled by a single cooling fan 10.

[0016] In the electronic device 90, components that generate more heat than components on the upper side of the circuit board 80 are mounted on the lower side 80b of the circuit board 80. Therefore, as will be described in detail later, the impeller 20 and the circuit board 80 are arranged and configured to supply more air to the lower side 80b of the circuit board 80 than to the upper side 80a of the circuit board 80. Components that generate a large amount of heat, such as integrated circuits such as a CPU, GPU, or memory, or a SoC (System on a Chip) having these functions, may be provided on the lower side 80b of the circuit board 80.

[0017] 3, the primary fin 21 is a plate-like member formed along the axial direction (Z1-Z2 direction) and extends radially outward from the impeller 20. An inner end 21a of the primary fin 21 (an end closer to the axis C1 in the radial direction) may be connected to an outer edge 22b of an annular inner guide ring 24, which will be described later. Alternatively, the inner end 21a of the primary fin 21 may be fixed to the cylindrical portion 30a of the motor housing 30.

[0018] As shown in Figure 2, when the impeller 20 rotates, air is introduced into the impeller 20 from the upper and lower sides thereof and is then blown outward in the radial direction of the impeller 20. In other words, the cooling fan 10 is a centrifugal fan. (In Figure 2, the air flow introduced from the upper side is labeled F21, and the air flow introduced from the lower side is labeled F11.) As described above, the cooling fan 10 has a base plate 40. When the impeller 20 rotates, air is introduced into the impeller 20 through a gap between the central base portion 42 and the outer peripheral base portion 41 of the base plate 40.

[0019] 4A , each guide fin 22 is formed between two adjacent main fins 21 in the rotation direction of the impeller 20. Each guide fin 22 is a plate-like member formed along the axial direction. The size of each guide fin 22 is smaller than that of the main fins 21.

[0020] With this structure, the airflows F24 and F12 (see FIG. 2) that pass between two adjacent main fins 21 and are blown outward in the radial direction can be adjusted by the guide fins 22. As a result, the cooling performance of the cooling fan 10 for heat-generating components can be improved. Also, if the number of fins is too large, the amount of blown air may actually be reduced, but in the cooling fan 10, the size of the guide fins 22 is smaller than the size of the main fins 21, so this disadvantage can be suppressed.

[0021] 4B , the guide fin 22 has an inner end (inner edge) 22a located toward the center of the impeller 20 and an outer end (outer edge) 22b located radially outward. The primary fin 21 also has an inner end 21a located toward the center of the impeller 20 and an outer end (outer edge) 21b located radially outward. The distance L2 from the inner end 22a to the outer end 22b of the guide fin 22 in the direction along the primary fin 21 is smaller than the distance L1 from the inner end 21a to the outer end 21b of the primary fin 21 in the same direction.

[0022] 5, the size H2 of the guide fin 22 in the axial direction is smaller than the size H1 of the main fin 21 in the axial direction. More specifically, the size H2 of the guide fin 22 may be smaller than half the size H1 of the main fin 21.

[0023] Thus, in the cooling fan 10, the size of the guide fins 22 is smaller than that of the main fins 21 in both the axial direction and the direction perpendicular thereto.

[0024] [Position of Guide Fins] As shown in Figure 5, the main fin 21 has inner edges 21c and 21d that are located radially closer to the axis C1. The inner edge 21c extends downward from an upper end 21e of the outer periphery of the main fin 21 toward the axis C1. Conversely to the inner edge 21c, the inner edge 21d extends upward from a lower end 21f of the outer periphery of the main fin 21 toward the axis C1. The guide fin 22 is located radially outward of the inner edges 21c and 21d of the main fin 21. The outer end 22b of the guide fin 22 is located radially closer to the axis C1 than the outer end 21b of the main fin 21. This effectively reduces noise caused by air hitting the guide fins 22.

[0025] 5, the inner edges 21c and 21d of the main fin 21 may be gently curved. More specifically, the connecting portion between the inner edge 21c and the upper end 21e of the main fin 21 and the connecting portion between the inner edge 21d and the lower end 21f may be curved. This can reduce noise during rotation of the impeller 20 (noise caused by the inner edges 21c and 21d hitting the air).

[0026] As shown in Figure 5, the guide fin 22 is located between the outer peripheries of two adjacent main fins 21. In other words, the position of the guide fin 22 is shifted radially outward from the center M1 of the main fin 21 in the direction along the main fin 21. Here, the center M1 of the main fin 21 is an arc that passes through the midpoint between the inner end 21a and the outer end 21b in the direction along the main fin 21. The entire guide fin 22 may be located radially outward from the center M1 of the main fin 21. The impeller 20 sends air radially outward by the outer peripheries of the main fins 21. Because the guide fin 22 is located between the outer peripheries of two adjacent main fins 21, it can guide air toward the outer peripheries of the main fins 21.

[0027] 4B , the primary fin 21 may extend in a direction oblique to both the radial direction and the rotational direction of the impeller 20. The primary fin 21 may be curved along a portion of a clothoid curve. This shape of the primary fin 21 can increase the efficiency of air introduction and delivery by the cooling fan 10.

[0028] 4B shows two primary fins 21_1 and 21_2 that are adjacent to each other in the rotation direction. The primary fin 21_2 is located on the opposite side of the primary fin 21_1 in the rotation direction R1 of the impeller 20. The primary fin 21_1 is located upstream in the rotation direction of the impeller 20, and the primary fin 21_2 is located downstream in the rotation direction of the impeller 20.

[0029] 4B, the guide fin 22 may be inclined with respect to the main fins 21_1 and 21_2. More specifically, the guide fin 22 may be inclined so that a distance G2 between the guide fin 22 and the main fin 21_2 gradually decreases outward in the radial direction. Here, the distance G2 is the distance between the main fin 21_2 and the guide fin 22 in a direction perpendicular to the surface of the main fin 21_2.

[0030] 4B, when the impeller 20 rotates, the primary fins 21 generate an airflow F12a that spreads radially outward. This airflow F12a is guided by the guide fins 22 toward the primary fins 21_2 (see airflow F12b). The airflow F12b is then sent out of the impeller 20 by the primary fins 21_2 (see airflow F12c). This action of the guide fins 22 can improve the cooling performance of the cooling fan 10. For example, the air flow velocity can be increased.

[0031] 4B , the inner end 22 a of the guide fin 22 is located closer to the primary fin 21_1 than the intermediate position Ma between the two primary fins 21_1 and 21_2. This arrangement of the guide fin 22 makes it possible to increase the amount of air guided by the guide fin 22 toward the primary fin 21_2. Here, the intermediate position Ma is a position on a straight line that passes through the inner end 22 a and extends in a direction perpendicular to the surface of the primary fin 21_2.

[0032] 4B, the distance G1 between the guide fin 22 and the main fin 21_1 gradually increases radially outward, in contrast to the distance G2. Here, the distance G1 is the distance between the main fin 21_1 and the guide fin 22 in a direction perpendicular to the surface of the main fin 21_1.

[0033] As shown in Fig. 4B, the outer end 22b of the guide fin 22 may be located closer to the primary fin 21_2 than the intermediate position Mb between the two primary fins 21_1 and 21_2. Here, the intermediate position Mb is a position on a straight line that passes through the outer end 22b and is perpendicular to the surface of the primary fin 21_2. Unlike the example shown in Fig. 4B, the outer end 22b of the guide fin 22 may be located closer to the primary fin 21_1 than the intermediate position Mb between the two primary fins 21_1 and 21_2.

[0034] [Relationship between Guide Fins and Guide Ring] The impeller 20 may have an outer guide ring 23 (see FIG. 3). As shown in FIG. 5, the outer guide ring 23 is located between the upper end 21e and the lower end 21f of the main fins 21 in the axial direction (Z1-Z2 direction). That is, the outer guide ring 23 is located downwardly away from the upper end 21e and upwardly away from the lower end 21f. The outer guide ring 23 is annular and surrounds the entire periphery of the motor housing 30, connecting all of the main fins 21. The outer guide ring 23 is formed to match the position of the circuit board 80 (its position in the axial direction). The outer guide ring 23 can increase the flow velocity of air delivered to the circuit board 80.

[0035] The above-described guide fins 22 may be formed on the outer guide ring 23. This increases the degree of freedom in the position of the guide fins 22. That is, because the outer guide ring 23 is annular and connects the multiple primary fins 21, it becomes easy to adjust the position and inclination of the guide fins 22 between two adjacent primary fins 21 when designing the impeller 20. For example, it becomes easy to adjust the distance G2 between the inner end 22a of the guide fin 22 and the primary fin 21_2.

[0036] As will be described later, the speed of the airflow delivered from the impeller 20 varies depending on the height (position in the axial direction), and is faster at the heights of the outer guide ring 23 and the inner guide ring 24, which will be described later. The outer guide ring 23 is formed to match the position of the circuit board 80. Since the guide fins 22 are formed on the outer guide ring 23, the speed of the airflow delivered to the circuit board 80 can be increased.

[0037] As shown in FIG. 5 , the guide fins 22 may have upper portions 22g formed above the outer guide ring 23 and lower portions 22h formed below the outer guide ring 23. This arrangement of the guide fins 22 can reduce the distance from the outer guide ring 23 to the ends (upper and lower ends) of the guide fins 22 compared to when the entire guide fins 22 are formed below the outer guide ring 23. Therefore, deflection of the guide fins 22 during rotation of the impeller 20 can be reduced. This arrangement of the guide fins 22 can also increase the velocity of both the airflow F24 (see FIG. 2 ) formed above the circuit board 80 and the airflow F12 (see FIG. 2 ) formed below the circuit board 80. Furthermore, because the guide fins 22 are formed on the outer guide ring 23, which is located between the upper end 21e and the lower end 21f of the main fin 21, it is easy to adjust the position of the guide fins 22 in the axial direction.

[0038] 5, the vertical width Wg of the upper portion 22g of the guide fin 22 is greater than the vertical width Wh of the lower portion 22h of the guide fin 22. This increases the speed of the airflow F24 formed by the guide fin 22 along the upper surface 80a of the circuit board 80.

[0039] [Inner Guide Ring and Outer Guide Ring] The impeller 20 may have an inner guide ring 24 (see FIG. 3) in addition to the outer guide ring 23. As shown in FIG. 5, the inner guide ring 24 is located closer to the center (axis C1) in the radial direction than the outer guide ring 23. The inner edge (the end closer to the axis C1) of the inner guide ring 24 may be connected to the outer peripheral surface of the motor housing 30. Like the outer guide ring 23, the inner guide ring 24 is located between the upper end 21e and the lower end 21f of the primary fins 21 in the axial direction (Z1-Z2 direction). In other words, the inner guide ring 24 is located downward from the upper end 21e and upward from the lower end 21f. The inner guide ring 24 is annular and surrounds the entire circumference of the motor housing 30, connecting all of the primary fins 21.

[0040] The inner guide ring 24 and the outer guide ring 23 guide the air that has flowed into the impeller 20 radially outward. For example, as shown in Fig. 2, air flows F22 and F24 are formed, which are guided by the upper surface of the outer guide ring 23 and sent out radially outward, an air flow F23 is formed between the outer guide ring 23 and the inner guide ring 24, and air flows F11 and F12 are formed, which are guided by the lower surface of the outer guide ring 23 and the lower surface of the inner guide ring 24 and sent out radially outward.

[0041] 2, the circuit board 80 may be disposed above a horizontal plane H4 that passes through, for example, the midpoint between the upper end 21e and the lower end 21f of the main fin 21. The inner guide ring 24 may be positioned below the circuit board 80. The outer guide ring 23 may be positioned above the inner guide ring 24. As a result, air that flows into the impeller 20 from below and hits the inner guide ring 24, and air that flows into the impeller 20 from above and hits the inner guide ring 24 (air F23 that passes between the two rings 24, 23) are sent toward the bottom of the circuit board 80.

[0042] As described above, the speed of the airflow discharged from the impeller 20 varies depending on the height (position in the axial direction), becoming faster with the height of the rings 24 and 23. The inner guide ring 24 is positioned below the circuit board 80, which contributes to improving the airflow rate and flow velocity along the lower surface 80b of the circuit board 80. The outer edge 23c (see FIG. 5) of the outer guide ring 23 is positioned slightly below the circuit board 80. This arrangement of the outer guide ring 23, together with the inner guide ring 24, contributes to improving the airflow rate along the lower surface 80b of the circuit board 80. Furthermore, while the outer guide ring 23 is positioned above the inner guide ring 24, the inner edge 23b (see FIG. 5) of the outer guide ring 23 is positioned at substantially the same height as the circuit board 80. This arrangement of the outer guide ring 23 contributes to improving the airflow rate and flow velocity along the upper surface 80a of the circuit board 80.

[0043] 4A, the impeller 20 may have an outer ring 25 that connects the outer ends 21b of the main fins 21. The outer ring 25 may connect the lower ends of the outer ends 21b of the main fins 21, for example.

[0044] The positional relationship between the rings 24 and 23 and the circuit board 80 is not limited to the example shown in FIG. 2 and the like.

[0045] [Electronic Device] An electronic device 90 (see FIG. 6) equipped with the cooling fan 10 will be described. The electronic device 90 is, for example, an entertainment device that functions as a game device or audio-visual device. The electronic device 90 outputs moving image data generated by executing a game program, video and audio data acquired via a network, and video and audio data acquired from a recording medium such as an optical disc to a display device such as a television. The electronic device may also be a personal computer or a server computer.

[0046] As shown in FIG. 6 , the electronic device 90 has a device main body 91. The device main body 91 has a housing 91a. The housing 91a houses the cooling fan 10 described above. The cooling fan 10 is arranged so that an axis C1 passing through its center of rotation faces the vertical direction of the electronic device 90. The housing 91a also houses a circuit board on which various electronic components such as a CPU and a GPU are mounted. The housing 91a has a heat sink (heat pipe, etc.). The heat sink is connected to the electronic components such as the CPU. The cooling fan 10 introduces external air into the housing 91a and forms an airflow that passes through the heat sink.

[0047] The electronic device 90 has an upper exterior panel 92 that covers the upper surface of the housing 91a. The electronic device 90 also has a lower exterior panel 93 that covers the lower surface of the housing 91a. 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 intakes Sa, Sb, Sc, and Sd for introducing outside air into the electronic device 90, as shown in FIG.

[0048] As shown in Figure 7, when the cooling fan 10 is driven, air is introduced through the upper air intakes Sa and Sb. This 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. When the cooling fan 10 is driven, air is introduced through the lower air intakes Sc and Sd. This air 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.

[0049] 7, the cooling fan 10 is disposed on the edge of the circuit board 80. The air introduced into the cooling fan 10 is blown outward in the radial direction by the rotation of the impeller 20, forming airflows above and below the circuit board 80.

[0050] [Summary] (1) As described above, the cooling fan proposed in this disclosure has a plurality of main fins arranged around an axis, and a plurality of guide fins arranged around the axis, each of which is positioned between two adjacent main fins in the circumferential direction around the axis and is smaller in size than the main fins.

[0051] With this structure, the guide fins can adjust the flow of air sent outward in the radial direction by the main fins. As a result, the cooling fan's cooling performance for heat-generating components can be improved. Also, while increasing the number of fins can actually reduce the amount of air sent out, this disadvantage can be reduced because the size of the guide fins is smaller than the size of the main fins.

[0052] (2) In the cooling fan of (1), the size of the guide fins in the direction along the axis is smaller than the size of the main fins in the direction along the axis.

[0053] (3) In the cooling fan of (1) or (2), each main fin has an inner end located radially closer to the axis and an outer end located radially outward. Each guide fin has an inner end located radially closer to the axis and an outer end located radially outward. The size of the guide fin, expressed as the distance between the inner end and the outer end of the guide fin in a direction along the main fin, is smaller than the size of the main fin, expressed as the distance between the inner end and the outer end of the main fin in a direction along the main fin.

[0054] (4) In the cooling fan according to any one of (1) to (3), each guide fin is inclined with respect to the two adjacent main fins.

[0055] (5) The cooling fan described in any one of (1) to (4) further includes an electric motor that rotates the multiple primary fins and the multiple guide fins in a first rotational direction, which is one of the clockwise and counterclockwise directions. The multiple primary fins include a first primary fin and a second primary fin positioned relative to the first primary fin in a second rotational direction, which is the other of the clockwise and counterclockwise directions. The guide fin positioned between the first primary fin and the second primary fin is arranged so that the distance between the second primary fin and the guide fin gradually decreases toward the outside in the radial direction. When the impeller rotates, the primary fins generate an airflow that spreads radially outward. This airflow is guided toward the second primary fin by the guide fin. The second primary fin then sends this airflow to the outside of the impeller. This action of the guide fin 22 can improve the cooling performance of the cooling fan 10. For example, it can increase the airflow velocity.

[0056] (6) The cooling fan according to any one of (1) to (5) further includes a guide ring extending in the circumferential direction around the axis and connected to the plurality of main fins. The guide fins are formed on the guide ring. This makes it easy to adjust the position and inclination of the guide fins between two adjacent main fins during impeller design.

[0057] (7) In the cooling fan described in (6), each main fin has a first end portion along the axis and a second end portion opposite the first end portion. The guide ring is located between the first end portion and the second end portion along the axis. This structure can suppress deflection of the guide fins when the impeller 20 rotates.

[0058] (8) In the cooling fan described in any one of (1) to (7), the position of the guide fin in the radial direction is shifted outward in the radial direction from the center in the direction along the main fin. With this structure, the guide fin can guide air toward the outer periphery of the main fin, which sends the air outward in the radial direction. As a result, the guide fin can more effectively adjust the air flow.

[0059] (9) In the cooling fan described in any one of (1) to (8), the main fins have outer ends positioned radially outward, and the guide fins are positioned radially closer to the axis than the outer ends of the main fins. This structure effectively reduces noise caused by air hitting the guide fins.

[0060] (10) The electronic device proposed in this disclosure includes a circuit board on which a heat-generating component is mounted, and a cooling fan for cooling the heat-generating component as described in any one of (1) to (9).

[0061] [Modifications] The cooling fan proposed in the present disclosure is not limited to the cooling fan 10 described above.

[0062] For example, the cooling fan proposed in the present disclosure may not have the inner guide ring 24 .

[0063] 5, the entire guide fins 22 may be positioned below the outer guide ring 23. This allows the position of the guide fins 22 to be lowered. Conversely, the entire guide fins 22 may be positioned above the outer guide ring 23. This allows the position of the guide fins 22 to be raised.

[0064] The cooling fan proposed in the present disclosure does not need to have the outer guide ring 23. In this case, the guide fins 22 may be connected to the outer peripheral surface of the motor housing 30, for example.

[0065] In yet another example, the distance G2 between the guide fin 22 and the main fin 21_2 may be constant in the radial direction.

Claims

1. A cooling fan having: a plurality of main fins arranged around an axis; and a plurality of guide fins arranged around the axis, each of which is positioned between two adjacent main fins in the circumferential direction around the axis and is smaller in size than the main fins.

2. The cooling fan according to claim 1, wherein the size of the guide fins in the direction along the axis is smaller than the size of the main fins in the direction along the axis.

3. A cooling fan as described in claim 1, wherein each main fin has an inner end located radially closer to the axis and an outer end located radially outward, and each guide fin has an inner end located radially closer to the axis and an outer end located radially outward, and the size of the guide fin, expressed as the distance between the inner end and the outer end of the guide fin in the direction along the main fin, is smaller than the size of the main fin, expressed as the distance between the inner end and the outer end of the main fin in the direction along the main fin.

4. The cooling fan according to claim 1, wherein each guide fin is inclined relative to the two adjacent main fins.

5. A cooling fan as described in claim 1, further comprising an electric motor that rotates the plurality of main fins and the plurality of guide fins in a first rotational direction that is one of a clockwise direction and a counterclockwise direction, wherein the plurality of main fins include a first main fin and a second main fin that is positioned further than the first main fin in a second rotational direction that is the other of the clockwise direction and the counterclockwise direction, and wherein the guide fin positioned between the first main fin and the second main fin is arranged so that the distance between the second main fin and the guide fin gradually decreases outward in the radial direction.

6. The cooling fan according to claim 1, further comprising a guide ring extending in the circumferential direction around the axis and connected to the plurality of main fins, the guide fins being formed on the guide ring.

7. A cooling fan as described in claim 1, wherein each main fin has a first end in a direction along said axis and a second end opposite said first end, and said guide ring is located between said first end and said second end in the direction along said axis.

8. The cooling fan according to claim 1, wherein the position of the guide fin in the radial direction is shifted outward in the radial direction from the center in the direction along the main fin.

9. A cooling fan as described in claim 1, wherein the main fins have outer ends positioned radially outward, and the guide fins are positioned closer to the axis in the radial direction than the outer ends of the main fins.

10. An electronic device comprising: a circuit board on which a heat-generating component is mounted; and a cooling fan according to claim 1 for cooling the heat-generating component.

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