JP2014045086A - Heat sink - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat sink which improves heat radiation performance thereby achieving weight reduction, facilitates the manufacturing, and improves the durability.SOLUTION: A heat sink 1 is formed by erecting multiple heat radiation fins 3 on a rear surface of a base plate 2 so that the heat radiation fins 3 are arranged along a cooling air flow direction and in parallel with each other. High heat transfer rate parts 3a and low heat transfer rate parts 3b are alternately arranged along the cooling air flow direction on both surfaces of each heat radiation fin 3. For example, the high heat transfer rate parts 3a and the low heat transfer rate parts 3b face each other on opposing surfaces of the adjacent heat radiation fins 3.

Description

  The present invention relates to a heat sink in which a plurality of radiating fins are erected on the back surface of a base plate.

  In recent years, the amount of heat generation has increased as the power consumption of semiconductors has increased at an accelerated rate, so that the demand for high-performance cooling systems has increased. In addition, even in a circuit integrated at a high density for miniaturization, the power consumed tends to increase, and the heat generation density increases rapidly at the same time as the heat generation amount.

  Also in LED (light emitting diode) which is a semiconductor, the use as a lighting is increasing from the use for the conventional display with the improvement in brightness, The power consumption is also increasing.

  However, the biggest problem with LED elements is that most of the input electric power becomes heat and the luminous efficiency is lowered by the heat generated by itself. In particular, an LED that consumes a large amount of power is required to have a heat dissipation structure that can receive heat of several watts per chip. In order to conduct this heat generation, instead of the conventional resin substrate, the heat conductivity is reduced. High metal core substrates and ceramic substrates have been put into practical use.

  Also, a cooling structure that suppresses heat generation of the LED by heat radiation by a heat sink in which a plurality of heat radiation fins are erected on the back surface of the base plate has been put into practical use. Here, an example of the cooling structure by the heat sink of the conventional illuminating device is shown in FIG.

  That is, FIG. 7 is a diagram showing an example of a conventional cooling structure using a heat sink, where (a) is a plan view, (b) is a front view, (c) is a side view, and (d) is a perspective view. The illustrated heat sink 11 is made of an aluminum alloy having a high thermal conductivity, and a plurality of rectangular plate-like sheets (in the figure, the vertical direction in FIG. 7) that are long on the back surface of the rectangular plate-like base plate 12. In the example shown, eleven (11) radiating fins 13 are vertically arranged at an appropriate interval in the left-right direction (direction orthogonal to the flow direction of the cooling air), and the LED 10 as the light source is located at the center of the surface of the base plate 12. It is mounted on.

  Thus, when the LED 10 which is a light source is energized and emits light, the heat generated from the LED 10 is conducted from the base plate 12 of the heat sink 11 to the heat radiation fins 13 and is radiated from the heat radiation fins 13 into the air. By this, LED10 is cooled and the temperature rise is suppressed.

  By the way, in order to improve the heat dissipation performance of the heat sink 11, the total heat transfer area of the heat dissipating fins 13 may be increased. For that purpose, the arrangement pitch of the heat dissipating fins 13 may be narrowed to increase the number of the heat dissipating fins 13. Conceivable.

  Further, regarding the heat sink, Patent Document 1 discloses that a surface (envelope surface) in contact with the wing-shaped radiation fin located at the cooling air introduction position is curved so as to protrude downstream of the cooling air, and is placed at the cooling air discharge position. There has been proposed a configuration in which a surface (envelope surface) in contact with a wing-shaped radiating fin positioned is curved so as to protrude to the upstream side of the cooling air. According to this configuration, the flow resistance of the cooling air passing through the heat sink is greatest at both sides of the heat sink and decreases toward the center of the heat sink, so the speed and amount of cooling air passing through the center of the heat sink increases. The heat generated by the high heat generating element attached to the lower part of the central portion of the heat sink can be effectively dissipated.

  Here, FIG. 8 shows a state of heat radiation by one radiation fin 13, and the cooling air flowing from below with respect to the radiation fin 13 is a laminar boundary layer that is a layer of air warmed on both surfaces of the radiation fin 13. BL is formed, and this laminar boundary layer BL grows from the tip of the radiation fin 13 toward the flow direction of the cooling air (upward in FIG. 8), and its thickness gradually increases. Since the thermal emissivity of the laminar boundary layer BL is lower than the thermal emissivity of the outer region, the thermal emissivity (the length of the arrow in FIG. Since the thickness of the laminar boundary layer BL increases from there toward the downstream in the flow direction of the cooling air (upward in FIG. 8), the thermal emissivity decreases.

  Accordingly, when each radiating fin 13 is long and continuous in the flow direction of the cooling air as in the heat sink 11 shown in FIG. 7, it is formed on the opposing surfaces of the adjacent cooling fin 13 as shown in FIG. The laminar boundary layer BL to be grown grows and overlaps in the flow direction of the cooling air, and the flow path between the two radiating fins 13 is covered with the laminar boundary layer BL. Will occur. Such a problem also occurs in the heat sink proposed in Patent Document 1.

  Therefore, Patent Document 2 proposes a cooling structure shown in FIG.

  10 is a view showing the cooling structure proposed in Patent Document 2, wherein (a) is a plan view, (b) is a front view, (c) is a side view, and (d) is a perspective view. In the illustrated heat sink 11, two types of plate-like heat radiation fins 13, 14 having different lengths on the back surface of the base plate 12 are staggered in the direction perpendicular to the cooling air flow direction F (the left-right direction in FIG. 10). Arranged vertically and parallel.

  According to such a cooling structure, heat generated from the LED 10 that is a heat generation source is conducted from the base plate 12 of the heat sink 11 to the radiation fins 13 and 14 and is radiated from the radiation fins 13 and 14 to the air. The LED 10 is cooled by the above and the temperature rise is suppressed. However, since the plurality of heat radiation fins 13 and 14 having different lengths of the heat sink 11 are alternately arranged in the direction (left-right direction) perpendicular to the flow direction F of the cooling air, The lengths L1 and L2 of the radiating fins 13 and 14 can be made shorter than the length of the radiating fins 13 of the heat sink 11 shown in FIG. 7. For example, as shown in FIG. The thickness of the laminar boundary layer BL to be reduced is reduced, and the interval P between adjacent radiating fins 13 and radiating fins 14 is increased. It can be. For this reason, between the adjacent ones of the radiation fins 13 and 14 having different lengths in the left-right direction (cooling air flow path) grows and is blocked by the laminar boundary layer BL whose thickness is increased. Therefore, the heat radiation performance of the heat radiation fins 13 and 14 is enhanced, and the heat radiation performance of the heat sink 11 as a whole is enhanced. As a result, the number of the radiating fins 13 and 14 (the number converted to one continuous radiating fin) can be reduced, and the weight of the heat sink 11 can be reduced. FIG. 11 is an enlarged detail view of part A in FIG.

Japanese Patent No. 3405900 JP 2012-084834 A

  However, in the cooling structure shown in FIG. 10 proposed in Patent Document 2, when the heat sink 11 is viewed from the upstream side in the flow direction of the cooling air, the radiating fins 13 and 14 are interrupted in the middle. The part where the heat radiation fins 13 and 14 are interrupted does not directly contribute to heat radiation, and there is a problem in that there is a limit to improving the heat radiation efficiency.

  Further, since the two types of heat radiation fins 13 and 14 having different lengths are alternately arranged in the direction orthogonal to the flow direction F of the cooling air on the back surface of the base plate 12 of the heat sink 11, the heat sink 11 is manufactured. In addition, since the length of each of the radiating fins 13 and 14 is relatively short and the portion connected to the base plate 12 is small, the radiating fins 13 and 14 are broken when a force is applied to the radiating fins 13 and 14. There was a problem of durability that it was easy.

  The present invention has been made in view of the above problems, and a target heat sink is capable of improving the heat dissipation performance and reducing the weight thereof, as well as facilitating manufacture and improving durability. Is to provide.

  In order to achieve the above object, the illumination device according to claim 1 is a heat sink in which a plurality of radiating fins are erected in parallel with each other along the flow direction of the cooling air on the back surface of the base plate. The high emissivity portions and the low emissivity portions are alternately arranged along the flow direction of the cooling air.

  The invention described in claim 2 is characterized in that, in the invention described in claim 1, the high emissivity part and the low emissivity part are opposed to each other on the opposing surfaces of the adjacent radiating fins.

  The invention according to claim 3 is characterized in that, in the invention according to claim 1, the high emissivity parts and the low emissivity parts are opposed to each other on the opposing surfaces of the adjacent radiating fins. Features.

  According to a fourth aspect of the present invention, in the first aspect of the present invention, the high emissivity portions and the low emissivity portions are opposed to each other in the flow direction of the cooling air on the opposing surfaces of the adjacent radiating fins. It is characterized by comprising.

  The invention according to claim 5 is the invention according to any one of claims 1 to 4, wherein the high emissivity part is formed by partially subjecting the material of each of the heat dissipating fins to the material itself. The low emissivity part is used.

  According to invention of Claim 1, since the high emissivity part and the low emissivity part were alternately arrange | positioned along the flow direction of a cooling wind on both surfaces of each radiating fin, the laminar flow formed along each radiating fin The boundary layer disappears or becomes thin at the low emissivity part. For this reason, the laminar boundary layer does not continuously grow along the flow direction of the cooling air in each radiating fin and its thickness does not increase, and the laminar boundary layer is suppressed to a certain thickness or less. The heat radiation performance of each heat radiation fin is improved. As a result, the heat dissipation performance of the entire heat sink is improved, and the weight of the heat sink can be reduced by reducing the number of heat dissipation fins.

  In addition, since each radiating fin of the heat sink is configured as a single continuous structure without being divided in the middle, manufacturing of the heat sink is facilitated and each radiating fin is relatively long. Since the portion coupled to the base plate is large, even if a force is applied to the radiating fin, the radiating fin is not easily broken, and the durability of the heat sink is improved.

  According to the second aspect of the present invention, since the high emissivity portion and the low emissivity portion are opposed to each other on the opposing surfaces of the adjacent radiating fins of the heat sink, a laminar boundary layer is formed between the adjacent radiating fins. Will occur alternately on the left and right, and the space between the adjacent radiating fins (arrangement pitch) can be narrowed to reduce the size and weight of the heat sink.

  According to the invention described in claim 3, since the high emissivity portions and the low emissivity portions are opposed to each other on the opposing surfaces of the adjacent heat dissipation fins of the heat sink, the layer generated between the adjacent heat dissipation fins The flow boundary layer becomes symmetrical, and the cooling air passing between the radiation fins goes straight and the flow velocity is increased, so that the heat dissipation of the heat sink is more effectively enhanced.

  According to the invention described in claim 4, since the high emissivity portions and the low emissivity portions are opposed to each other in the flow direction of the cooling air on the opposing surfaces of the adjacent heat dissipation fins of the heat sink, Both of the effects of the inventions of claim 2 and claim 3 can be enjoyed to a certain extent, and the heat sink is improved by increasing the flow velocity of the cooling air passing between the radiating fins while reducing the size and weight of the heat sink. The heat dissipation can be improved.

  According to the invention described in claim 5, by subjecting the material of each radiating fin of the heat sink to a surface treatment, a high emissivity portion and a low radiating portion are provided on both surfaces of each radiating fin along the flow direction of the cooling air. Can be arranged alternately.

It is a perspective view of the heat sink which concerns on Embodiment 1 of this invention. It is a front view of the heat sink concerning Embodiment 1 of the present invention. It is a perspective view of the heat sink which concerns on Embodiment 2 of this invention. It is a front view of the heat sink which concerns on Embodiment 2 of this invention. It is a perspective view of the heat sink concerning Embodiment 3 of the present invention. It is a front view of the heat sink which concerns on Embodiment 3 of this invention. It is a figure which shows an example of the cooling structure by the conventional heat sink, (a) is a top view, (b) is a front view, (c) is a side view, (d) is a perspective view. It is a figure which shows the mode of the thermal radiation with the radiation fin of 1 sheet. It is a figure which shows the form of the laminar flow boundary layer in an adjacent radiation fin. It is a figure which shows the cooling structure proposed in patent document 2, Comprising: (a) is a top view, (b) is a front view, (c) is a side view, (d) is a perspective view. It is the A section enlarged detail drawing of FIG.10 (b).

  Embodiments of the present invention will be described below with reference to the accompanying drawings.

<Embodiment 1>
FIG. 1 is a perspective view of a heat sink according to the first embodiment of the present invention, and FIG. 2 is a front view of the heat sink. Therefore, an external cooling method using cooling air from below to above is employed.

  Thus, the heat sink 1 is integrally formed of a carbon material having a high emissivity, and the surface of the base plate 2 having a rectangular plate shape follows the flow direction of the cooling air (the vertical direction in FIGS. 1 and 2). A plurality of plate-like radiating fins 3 are erected vertically and in parallel. In this embodiment, the high emissivity portions (hatched and black portions) 3a and the low emissivity portions 3b are alternately arranged along the flow direction (vertical direction) of the cooling air on the left and right surfaces of each radiating fin 3. Is arranged in multiple.

  Here, in each heat radiating fin 3, the high emissivity portion 3a is formed by performing a surface treatment such as ion etching on a part of the surface of the carbon material, and the emissivity of the high emissivity portion 3a is It is set larger than the emissivity of the low emissivity part 3b. And in each radiation fin 3, the low radiation part 3b is comprised with the carbon material itself which is a raw material, The emissivity is set smaller than that of the high emissivity part 3a. In the present embodiment, in the heat radiation fin 3 of the heat sink 1, the emissivity of the high emissivity portion 3a subjected to the surface treatment is about 0.99, and the emissivity of the low emissivity portion not subjected to the surface treatment is 0. .76 to 0.79.

  In the heat sink 1 configured as described above, heat generated in a heat source (not shown) is conducted from the base plate 2 of the heat sink 1 to each radiation fin 3 and is radiated from each radiation fin 3 into the air. Although a heat source is cooled and the temperature rise is suppressed, according to the heat sink 1 which concerns on this Embodiment, the following effects are acquired.

  In other words, in the present embodiment, the high emissivity portions 3a and the low emissivity portions 3b are alternately arranged on both surfaces of each radiating fin 3 of the heat sink 1 along the flow direction of the cooling air. The formed laminar boundary layer disappears or becomes thin at the low emissivity portion 3b. For this reason, the laminar boundary layer does not continuously grow along the flow direction of the cooling air in each radiating fin 3 and the thickness thereof does not increase, and the laminar boundary layer is suppressed to a certain thickness or less. Thus, the heat radiation performance of each radiation fin 3 is improved. As a result, the heat dissipation performance of the heat sink 1 as a whole is improved, and the number of heat dissipating fins 3 can be reduced to reduce the size and weight of the heat sink 1.

  In particular, in the present embodiment, since the high emissivity portion 3 a and the low emissivity portion 3 b are opposed to each other on the opposing surfaces of the adjacent heat sink fins 3 of the heat sink 1, a layer is formed between the adjacent heat sink fins 3. The flow boundary layer is alternately generated on the left and right sides, and the space (arrangement pitch) between the adjacent radiating fins 3 can be narrowed to reduce the size and weight of the heat sink 1.

  Moreover, since each radiation fin 3 of the heat sink 1 which concerns on this Embodiment is comprised as one continuous structure without being divided on the way, manufacture of the heat sink 1 becomes easy, and each radiation fin 3 has a relatively long length and a large portion coupled to the base plate 2, so that even if a force is applied to the cooling fin 3, the heat radiation fin 3 is not easily broken, and the durability of the heat sink 1 is improved.

<Embodiment 2>
Next, a second embodiment of the present invention will be described below with reference to FIGS.

  3 is a perspective view of a heat sink according to Embodiment 2 of the present invention, and FIG. 4 is a front view of the heat sink. In these drawings, the same reference numerals are used for the same elements as those shown in FIGS. In the following, description thereof will be omitted.

  The present embodiment is characterized in that the high emissivity portions 3a and the low emissivity portions 3b are opposed to each other on the mutually opposing surfaces of the heat radiating fins 3 adjacent to the heat sink 1, and the other configurations are as described above. This is the same as that of the first embodiment.

  Thus, according to the heat sink 1 according to the present embodiment, since the high emissivity portion 3a and the low emissivity portion 3b are opposed to each other on the opposing surfaces of the adjacent radiating fins 3, the adjacent radiating fins are arranged. 3, the laminar boundary layer generated between the radiating fins 3 is symmetrical, and the cooling air passing between the radiating fins 3 goes straight and the flow velocity is increased, so that the heat dissipation of the heat sink 1 is further effectively improved.

  Also in the present embodiment, each radiating fin 3 of the heat sink 1 is configured as a single continuous structure without being divided in the middle. Since the length is relatively long and the portion connected to the base plate is large, even if a force is applied to the cooling fin, the heat radiation fin is not easily broken, and the durability of the heat sink is improved.

<Embodiment 3>
Next, a third embodiment of the present invention will be described below with reference to FIGS.

  FIG. 5 is a perspective view of a heat sink according to Embodiment 3 of the present invention, and FIG. 6 is a front view of the heat sink. In these drawings, the same components as those shown in FIGS. In the following, description thereof will be omitted.

  In the present embodiment, the high emissivity portions 3a and the low emissivity portions 3b are shifted from each other by a half of their length in the cooling air flow direction on the opposing surfaces of the adjacent heat radiating fins 3 of the heat sink 1. The other features are the same as those of the first embodiment.

  Thus, according to the heat sink 1 according to the present embodiment, the high emissivity portions 3a and the low emissivity portions 3b are shifted from each other in the cooling air flow direction on the opposing surfaces of the adjacent radiating fins 3. Since they are configured so as to face each other, both the effects of the first and second embodiments can be enjoyed to some extent, and while the heat sink 1 can be reduced in size and weight, the cooling air passing between the radiating fins 3 can be obtained. The heat dissipation of the heat sink 1 can be increased by increasing the flow rate.

  Also in the present embodiment, each radiating fin 3 of the heat sink 1 is configured as one continuous structure without being divided in the middle, so that the heat sink 1 can be easily manufactured and each radiating heat can be obtained. Since the fin 3 has a relatively long length and a large portion coupled to the base plate 2, even if a force is applied to the heat radiating fin 3, the heat radiating fin 3 is not easily broken and the durability of the heat sink 1 is improved. An effect is obtained.

DESCRIPTION OF SYMBOLS 1 Heat sink 2 Base plate of heat sink 3 Heat sink fin 3a High emissivity part of heat sink 3b Low emissivity part of heat sink

Claims (5)

In a heat sink in which a plurality of radiating fins are erected parallel to each other along the flow direction of the cooling air on the back surface of the base plate,
A heat sink, wherein high radiating portions and low emissivity portions are alternately arranged on both surfaces of each of the heat radiating fins along a flow direction of cooling air.   2. The heat sink according to claim 1, wherein the high emissivity portion and the low emissivity portion are opposed to each other on the opposing surfaces of the adjacent radiating fins.   2. The heat sink according to claim 1, wherein the high emissivity portions and the low emissivity portions are opposed to each other on opposite surfaces of the adjacent radiating fins.   The high emissivity portions and the low emissivity portions are opposed to each other in the flow direction of the cooling air on the opposing surfaces of adjacent radiating fins. Heat sink. 5. The high emissivity part is formed by partially performing a surface treatment on the material of each radiating fin, and the material itself is the low emissivity part. Heat sink.

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