JP2003258473A - Cooling device with heat sink - Google Patents

Abstract

(57) [Problem] To provide a cooling device provided with a heat sink that has high heat dissipation performance of fins even at a position away from the center of a substrate and can reduce the size of the device in the height direction. SOLUTION: The heat sink 1 is composed of a first fin group 3 composed of plate-like fins arranged in a radial direction, and a second fin group 4 composed of pin-shaped fins around the first fin group. The cooling fan 2 blows cooling air to the first fin group from the axial direction of the rotating shaft of the motor,
It operates to blow cooling air to the second fin group from a direction perpendicular to the axial direction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cooling device equipped with a heat sink that dissipates heat from a heat source, and more particularly to a cooling device suitable for cooling electronic components such as CPUs.

[0002]

2. Description of the Related Art The amount of heat generated from electronic parts such as a CPU used in a computer tends to increase more and more as its performance becomes higher. In Japanese Utility Model Publication No. 3-15982, a cooling fan is arranged on a heat sink in which a plurality of plate-shaped heat radiation fins are arranged radially on the surface of the substrate, and the air discharged from the cooling fan is directed to the central portion of the substrate. There is disclosed a cooling device having a structure in which the air is exposed to the outside and then the air is discharged to the outside through a plurality of radiation fins arranged in the radial direction. Also, U.S. Pat. No. 5,629,834, Japanese Patent No. 2,765,801 and Japanese Patent Laid-Open No. 7-111302.
No. 5792922) and US Pat. No. 5,792,292 (JP-A-9-1).
No. 02566) discloses a cooling device using a heat sink in which a plurality of plate-shaped fins are arranged along the flow of air radially flowing out from an impeller of a fan. Japanese Unexamined Patent Publication No. 2001-298140 discloses a cooling device using a heat sink in which a plurality of plate-shaped fins are radially arranged with a predetermined inclination angle with respect to the substrate surface.

[0003]

In the heat sinks of the first, second and third cooling devices, the cooling air is blown directly onto the plate-shaped fins from the direction perpendicular to the substrate surface immediately below and in the vicinity of the impeller of the cooling fan. Therefore, the heat dissipation performance is high, but the heat exchange progresses between the cooling air and the fins as the distance from the center of the substrate increases, and the temperature of the cooling air rises. Heat dissipation performance is low. For this reason, the cooling performance of the device is lowered. Also, the heat sink of the fourth cooling device is currently suitable for cooling recent high heat value CPUs. However, in the heat sink of the fourth cooling device, since the fins have a cylindrical outer shape, it is difficult to efficiently arrange the fins on the rectangular substrate, which causes a problem that the size in the height direction of the device becomes large. .

An object of the present invention is to provide a cooling device provided with a heat sink that has high fin heat dissipation performance even at a position away from the center of the substrate, and can reduce the size in the height direction of the device.

[0004]

SUMMARY OF THE INVENTION The present invention is directed to an improved cooling device having a heat sink for dissipating heat from a heat source. The heat sink is mounted on a substrate having a good heat conductivity and having a front surface and a back surface in contact with a heat source, so that heat can be transferred to the front surface of the substrate, and a plurality of plate-shaped heat radiation fins are arranged in a radial direction. The heat radiation fin unit includes one fin group and a second fin group in which a plurality of pin-shaped heat radiation fins are arranged upright. The cooling fan includes an impeller having a plurality of blades and rotated by a motor, and is attached to the heat sink so that the impeller is located above the first fin group of the heat sink.

The radiating fin unit has a positional relationship such that the second fin group surrounds the outer periphery of the first fin group, and has a height P1 from the substrate surface to the tip of the radiating fin of the second fin group. The ratio L = P2 / P1 of the height P2 from the substrate surface to the virtual plane including the virtual circle formed by the rotation of the lowermost edge of the impeller satisfies the relationship of 0.3 <L <0.9. The area ratio S = F2 / F1 between the total heat dissipation area F1 of the first fin group and the total heat dissipation area F2 of the second fin group satisfies the relationship of 0.1 <S <0.4. The cooling fan blows cooling air to the first fin group from the axial direction of the rotating shaft of the motor, and blows cooling air to the second fin group from a direction perpendicular to the axial direction.

In the second fin group of the heat sink used in the present invention, a plurality of pin-shaped heat dissipating fins are arranged in a concentric circle centered on the rotation axis of the motor, and are arranged with respect to the line of air flow from the cooling fan. Are staggered. Further, a concave shape that can be fitted with the cooling fan is formed on the outer peripheral side surface portion of the radiation fin of the first fin group.

As for the shape of the heat radiation fins immediately below and in the vicinity of the impeller of the cooling fan, it has been known in the experiments so far that the heat radiation performance is high when a plurality of plate-shaped fins are arranged in the radial direction. Therefore, in the cooling device provided with the heat sink of the present invention, the shape of the radiation fins of the first fin group located immediately below the impeller of the cooling fan is a plate shape,
It is arranged in the radial direction.

The cooling air blown to the first fin group from the axial direction of the rotating shaft of the motor flows between the fins of the first fin group to perform heat exchange, and the first fins along the substrate surface. It is quickly discharged toward the outer circumference of the group. Further, since the cooling fan blows cooling air from the opening formed on the side surface of the casing also in the direction perpendicular to the axial direction, the pin-shaped heat radiation fins of the second fin group arranged on the outer periphery of the first fin group are Air can be blown from a direction perpendicular to the upright direction of the pin. Since this cooling air does not exchange heat with the first fin group, it is possible to improve the heat dissipation performance of the second fin group on the outer peripheral portion of the substrate.

The pin-shaped heat radiation fins of the second fin group are arranged so as to surround the first fin group, but since the number of pin rows is 5 rows or less at most, the direction perpendicular to the upright direction of the pins. Even if air is blown from, the pressure loss is small,
In addition, the pins are arranged concentrically around the rotation axis of the motor in a staggered manner along the air flow, so that the air flow is locally complicated and heat exchange between the air and the pin-shaped heat radiation fins. Is promoted. Further, since the concave shape that can be fitted with the cooling fan is formed on the outer peripheral side surface of the radiation fin of the first fin group, there is no need to provide a space for fixing the cooling fan on the substrate, The number of heat radiation fins can be increased, and the cooling performance can be improved.

The radiating fins of the first fin group and the second fin group receive different cooling air from the cooling fan,
Since it is sprayed from different directions, the heat dissipation performance of the heat sink is high even at a position away from the center of the substrate, the cooling performance of the device is greatly improved, and the size in the height direction of the device can be reduced.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of a cooling device having a heat sink according to the present invention will be described below in detail with reference to the drawings. FIG. 1 is an exploded perspective view of an embodiment of a cooling device of the present invention. As shown in FIG. 1, this cooling device includes a heat sink 1 and a cooling fan 2. The heat sink 1 includes a substrate 5 having a front surface 5a and a back surface 5b in contact with a heat source, a first fin group 3 made up of plate-like fins arranged in a radial direction, and a second fin made up of pin-like fins around the fin. And a fin group 4 of. The substrate 5 is a metal material typified by an aluminum alloy or a copper alloy, a plate-like structure having a heat pipe structure inside, or a non-metal material such as a carbon material, which has excellent thermal conductivity and can be easily processed. It can be configured by.

The cooling fan 2 has an impeller 6. The impeller 6 has a plurality of blades 7 and is rotated by a motor 10. The housing of the motor 10 is supported by the casing 8 by three webs 11. In the casing 8, fixing pawls 9 are formed at two positions so that the rotation axis of the motor 10 is symmetrical. An opening 12 is formed in a part of the casing 8 and functions as an outlet for cooling air for the second fin group. A flow 21 of cooling air blown from the cooling fan 2 in the axial direction of the motor and a flow 22 of cooling air blown in the direction perpendicular to the axis are shown.

Recesses 9a which can be fitted with the cooling fan fixing pawls 9 are formed on the outer peripheral side surface portions of the radiation fins of the first fin group 3. The second fin group 4 is arranged so as to surround the first fin group 3. The cross section of the pin-shaped fins of the second fin group 4 is not limited to a circular shape, and may be a rectangular shape.

The air blown onto the first fin group 3 from the axial direction of the rotation shaft of the motor 10 by the cooling fan 2 flows between the adjacent fins of the plurality of plate-shaped heat radiation fins, and the substrate surface 5a. Along the outer periphery of the first fin group.

On the other hand, the second fin group 4 is blown by the cooling air from the opening 12 in the direction perpendicular to the axis. The cooling air from the opening 12 does not exchange heat with the first fin group, and the temperature of the cooling air has not risen. Therefore, the heat radiation of the second fin group 4 located on the outer peripheral portion of the substrate is dissipated. Performance improves. Further, when the cooling air flows between the pin-shaped radiating fins, the pins are alternately arranged concentrically with respect to the line of the air flow, so that the air flow becomes complicated and heat exchange is not performed. It accelerates and improves the heat dissipation performance.

Based on the above embodiment, 69 mm ×
Using a copper substrate of 83 mm x 4 mm, 77 copper plates of 31 mm x 15 mm x 0.3 mm are radially arranged as the first fin group, and 90 copper pins of 2 mm in diameter and 21 mm in length are used as the second fin group. A cooling device was prepared by arranging the fins around the first fin group and using a cooling fan having a diameter of 60 mm. The maximum external dimensions of this cooling device are 69 mm x
It was 83 mm × 34 mm. When a heat source of 73 W was brought into contact with the back surface of the heat sink of this cooling device and the cooling performance was tested, the thermal resistance value was 0.34 K / W. When tested under the same conditions using a cooling device which is considered to have the highest performance at present, the thermal resistance value is 0.34K.
Was / W. The size of this comparative cooling device is 69 mm
It was × 83 mm × 55 mm. Therefore, it has been possible to achieve downsizing of 35% or more as compared with the cooling device which is considered to have the highest performance at present.

According to the present invention, it is possible to improve the heat dissipation performance of the fin even at a position away from the center of the substrate.
Moreover, the height dimension of the device can be reduced without lowering the cooling performance.

[Brief description of drawings]

FIG. 1 is an exploded perspective view of an embodiment of a cooling device of the present invention.

[Explanation of symbols]

1 heat sink 2 Cooling fan 3 First fin group 4 Second fin group 5 substrates 5a Substrate surface 5b Back side of substrate 6 impeller 7 blade 8 casing 9 Claw for fixing cooling fan 9a recess 10 motors 11 web 12 openings 21 Flow of cooling air blown in the axial direction 22 Flow of cooling air blown in a direction perpendicular to the axis

Claims (4)

[Claims] 1. A cooling device comprising a heat sink for dissipating heat from a heat source, the substrate having good heat conductivity, the substrate having a front surface and a back surface in contact with the heat source, and heat transfer to the front surface of the substrate. A heat-dissipating fin, which is composed of a first fin group in which a plurality of plate-shaped heat-dissipating fins are arranged in a radial direction and a second fin group in which a plurality of pin-like heat-dissipating fins are vertically arranged. A heat sink having a unit, an impeller having a plurality of blades and rotated by a motor, and attached to the heat sink so that the impeller is located above the first fin group of the heat sink. A cooling fan, wherein the radiating fin unit has a positional relationship such that the second fin group surrounds the outer circumference of the first fin group, Ratio of the height P1 from the surface of the substrate to the tip of the radiation fin of the second fin group and the height P2 from the surface of the substrate to a virtual plane including a virtual circle formed by the rotation of the lowermost edge of the impeller. L = P2 / P1 is 0.3 <L <0.9
And the area ratio S = F2 / F1 of the total heat dissipation area F1 of the first fin group and the total heat dissipation area F2 of the second fin group is 0.1.
<S <0.4 is satisfied, the cooling fan blows cooling air to the first fin group from the axial direction of the rotation shaft of the motor, and the cooling fan is moved from a direction perpendicular to the axial direction. A cooling device which operates so as to blow cooling air to the second fin group. 2. The cooling device according to claim 1, wherein the radiation fins of the second fin group are arranged on a concentric circle centered on the rotation axis. 3. The radiating fins of the second fin group are arranged in a staggered manner with respect to the line of air flow from the cooling fan.
The cooling device according to. 4. The cooling device according to claim 1, wherein a concave shape that can be fitted into the cooling fan is formed on an outer peripheral side surface portion of the radiation fin of the first fin group.