JPWO2012114955A1 - Heat sink and method of using heat sink - Google Patents

Abstract

The heat sink (10) is used to cool the object to be cooled. The heat sink (10) is disposed on a base plate (1) in which heat-generating components are thermally connected and placed substantially vertically, and a plate surface of the base plate (1), and transfers heat to the cooling air. A plurality of pin fins (2) for performing. The plurality of pin fins (2) has a base plate (1) such that a pair of pin fin rows in which the pin fins (2) are linearly arranged at predetermined intervals form an approximately V shape that opens upward. It stands on the top.

Description

  The present invention relates to a heat sink used for cooling an object to be cooled such as various models including electronic devices such as a CPU, an integrated circuit, and a semiconductor element, and a method of using the heat sink.

  Heat sinks are used for heat dissipation in various devices including electronic devices such as CPUs, integrated circuits, and semiconductor elements. In recent years, for example, with the increase in the density of electronic devices, the amount of heat generated by these devices and the heat generation density tend to increase. Therefore, high-performance heat sinks with better cooling performance have been demanded.

  Furthermore, there is a strong demand for weight reduction especially when these devices are used in an automobile. For this purpose, a heat sink that can realize a desired performance only by natural air cooling without using a cooling fan is preferable.

  In addition, various devices in recent years have progressed in miniaturization. For this reason, for example, even if a heat sink can be mounted on an electronic device such as a CPU, an integrated circuit, or a semiconductor element, which is a heating element, a spatial fan mounting It is often difficult to secure a margin. Also from this viewpoint, a heat sink that can realize a desired performance only by natural air cooling is desired.

  Needless to say, if a heat sink that exhibits the desired performance can be realized without using a cooling fan, the manufacturing cost can be reduced. For the reasons described above, there is a strong demand for a higher performance heat sink that can achieve desired performance only by natural air cooling without using a cooling fan.

As heat sinks using only natural air cooling, heat sinks as described in Patent Documents 1 to 4 have been proposed so far.
Further, although not necessarily suitable for natural air cooling, a heat sink as disclosed in Patent Document 5 has been proposed.

Japanese Unexamined Patent Publication No. 08-88301 Japanese Patent Laid-Open No. 06-104583 JP 2010-251730 A Japanese Patent Laid-Open No. 05-102357 JP 2008-205421 A

Many conventional air-cooling heat sinks use plate-like fins as shown in Patent Documents 1 to 4. In Patent Document 4 labeled “Pin-type heat sink”, a large number of radiating fins are disposed on a heat receiving plate that transmits heat from the object to be cooled, but each pin has a thick cross-sectional shape. It is a thin, wide flat or ribbon-shaped flat pin (see paragraph 0008 of Patent Document 4), and it can be said that a plate-like fin is used.
Since the plate-like fin has a large heat radiation area, the cooling performance is good. However, since the plate-like fin is plate-like, it has a corresponding weight.

  The present invention has been made in view of the above problems, and an object of the present invention is to obtain a heat sink that is lightweight and has excellent cooling performance.

  The present invention uses pin fins instead of plate fins to obtain a lightweight heat sink. In general, when pin fins are used, the heat radiation area is reduced as compared with plate fins, so that the cooling performance is lowered. However, placing pin fins at a high density to the same heat radiation area as the plate fins not only does not reduce the weight, but also increases the resistance to the flow of cooling air. In other words, the cooling performance is lowered, which is not realistic at all.

To meet the purpose of the present invention, in order to have a heat dissipation performance comparable to that of plate fins even if pin fins are used, it is devised so that the flow of cooling air is accelerated and enhanced. It is important to improve the function of the fins so that the heat exchange efficiency between the air and the fins increases.
The present invention made as a result of intensive studies from this viewpoint is specifically as follows.

That is, the heat sink according to the first aspect of the present invention is:
A heat sink used to cool a cooling object,
A base plate erected so that an updraft generated by heat generated from the object to be cooled flows along the plate surface;
A pin fin group comprising a plurality of pin fins disposed on the plate surface of the base plate;
With
The pin fin group has a pair of pin fin rows in which a plurality of pin fins are arranged in a row at intervals from each other, and the pair of pin fin rows gradually spreads vertically between the rows. Arranged opposite to the horizontal direction,
It is characterized by that.

  The cross-sectional shape of the plurality of pin fins may be circular or elliptical.

  The cross-sectional shape of the plurality of pin fins may be a circle or an ellipse with an aspect ratio of 1.0 to 5.0.

  In addition, the cross-sectional shape of the plurality of pin fins may be an oval shape that is long from the outer vertical lower side to the inner vertical upper side of the pair of pin fin rows.

  In the pin fin group, the pair of pin fin rows may be repeatedly provided in two or more pairs in the horizontal direction.

  In the pair of pin fin rows, an angle formed by arrangement directions of the pin fins in each pin fin row may be 40 ° or less.

The method of using the heat sink according to the second aspect of the present invention is as follows:
A base plate and a pin fin group comprising a plurality of pin fins disposed on the plate surface of the base plate, the pin fin group having a pair of pin fin rows in which a plurality of pin fins are arranged in a row at intervals from each other The pair of pin fin rows is a method of using a heat sink disposed so as to face each other so as to gradually spread between the rows,
Ascending airflow generated by the heat generated from the cooling target flows along the plate surface of the base plate, and the pair of pin fin rows face each other in the horizontal direction so that the space between the rows gradually spreads vertically upward. In addition, the heat sink is arranged and used for natural air cooling,
It is characterized by that.

  The cross-sectional shape of the plurality of pin fins may be circular or elliptical.

  The cross-sectional shape of the plurality of pin fins may be circular or elliptical with an aspect ratio of 1.0 to 5.0.

  The cross-sectional shape of the plurality of pin fins may be an ellipse that is long in a direction crossing the arrangement direction of the pin fins in the pin fin row.

In the pin fin group, two or more pairs of the pin fin rows are provided,
The heat sink may be disposed so that the pair of pin fin rows are repeatedly disposed in two or more pairs in the horizontal direction.

  In the pair of pin fin rows, an angle formed by arrangement directions of the pin fins in each pin fin row may be 40 ° or less.

  Here, “the base plate is erected so that the updraft generated by the heat generated from the cooling target flows along the plate surface” or “the upflow generated by the heat generated from the cooling target along the plate surface of the base plate “Flow” means “the base plate is erected substantially vertically”. Specifically, the inclination of the base plate surface may be within a range of + 45 ° to −45 ° from the vertical direction, and +30 Good cooling performance can be obtained if it is within the range of from -30 °. Furthermore, if it is in the range of + 10 ° to −10 °, particularly good cooling performance can be obtained.

  Further, “the pin fin group has a pair of pin fin rows in which a plurality of pin fins are arranged in a row at intervals from each other, and the pair of pin fin rows is gradually moved vertically upward between the rows. In other words, it is arranged on the base plate so as to form a substantially V shape in which the pair of pin fin rows opens upward. It is a structure.

  Here, the term “substantially V-shaped” does not necessarily mean that the tip of the V-shape is completely closed as it is as the shape of “V”. For the reason, it is meant that the tip of the V shape may be appropriately vacated. To that end, the word “abbreviated” was prefixed.

  According to the heat sink and the method of using the heat sink of the present invention, it is possible to obtain a heat sink that is lightweight and has a high cooling performance, particularly a natural heat-cooling heat sink.

It is a perspective view which shows the heat sink of 3rd Embodiment of this invention. It is a front view which shows the heat sink of 3rd Embodiment. It is a perspective view which shows the heat sink of a comparative example. It is a front view which shows the heat sink of a comparative example. It is a perspective view explaining the calculation model used for simulation calculation. It is a figure which shows the air velocity distribution obtained by simulation calculation about the heat sink of the comparative example. It is a figure which shows the air velocity distribution obtained by simulation calculation about the heat sink of 3rd Embodiment. It is a figure which shows the relationship between the substantially V-shaped opening angle | corner (alpha) obtained by simulation calculation, and the maximum temperature rise value (DELTA) T of a baseplate. It is a figure which shows the air velocity distribution obtained by simulation calculation when opening angle (alpha) is 10 degrees. It is a figure which shows the air velocity distribution obtained by simulation calculation when opening angle (alpha) is 15 degrees. It is a figure which shows air velocity distribution obtained by simulation calculation when opening angle (alpha) is 20 degrees. It is a figure which shows the air velocity distribution obtained by simulation calculation when opening angle (alpha) is 25 degrees. It is a figure which shows air velocity distribution obtained by simulation calculation when opening angle (alpha) is 30 degrees. It is a figure which shows the air velocity distribution obtained by simulation calculation when opening angle (alpha) is 40 degrees. It is a figure which shows air velocity distribution obtained by simulation calculation when opening angle (alpha) is 50 degrees. It is a figure which shows the relationship between the pin fin gap | interval and the maximum temperature rise value (DELTA) T of a baseplate which were obtained by simulation calculation. It is a figure which shows the air velocity distribution obtained by the simulation calculation when a gap | interval is 1.25 mm. It is a figure which shows air velocity distribution obtained by simulation calculation when a clearance gap is 2.5 mm. It is a figure which shows the air velocity distribution obtained by the simulation calculation when a clearance gap is 3.5 mm. It is a figure which shows the relationship between the aspect ratio and the maximum temperature rise value (DELTA) T of a baseplate which were obtained by simulation calculation. It is a figure which shows the air velocity distribution obtained by the simulation calculation in the case of aspect ratio 3.26. It is a figure which shows the air velocity distribution obtained by the simulation calculation when the aspect ratio is 4.82. It is a front view which shows the heat sink of 4th Embodiment of this invention. It is a front view which shows the heat sink of 5th Embodiment of this invention. It is a front view which shows the heat sink of 6th Embodiment of this invention. It is a schematic front view which shows the heat sink of 1st Embodiment of this invention, and shows the example whose opening angle (alpha) is 2 degrees. It is a schematic front view which shows the heat sink of 1st Embodiment, and shows the example whose opening angle (alpha) is 3 degrees. It is a schematic front view which shows the heat sink of 1st Embodiment, and shows the example whose opening angle (alpha) is 5 degrees. It is a schematic front view which shows the heat sink of 1st Embodiment, and shows the example whose opening angle (alpha) is 10 degrees. It is a schematic front view which shows the heat sink of the comparative example whose opening angle (alpha) is 0 degree. It is a perspective view which shows the heat sink of 1st Embodiment when opening angle (alpha) is 10 degrees. It is a perspective view explaining the calculation model used for simulation calculation. It is a figure which shows the air velocity distribution obtained by simulation calculation when opening angle (alpha) is 2 degrees. It is a figure which shows the air velocity distribution obtained by simulation calculation when opening angle (alpha) is 3 degrees. It is a figure which shows air velocity distribution obtained by simulation calculation when opening angle (alpha) is 5 degrees. It is a figure which shows the air velocity distribution obtained by simulation calculation when opening angle (alpha) is 10 degrees. It is a figure which shows the air velocity distribution obtained by simulation calculation when opening angle (alpha) is 0 degree. It is a schematic front view which shows the heat sink of 2nd Embodiment, and shows the example whose opening angle (alpha) is 2 degrees. It is a schematic front view which shows the heat sink of 2nd Embodiment, and shows the example whose opening angle (alpha) is 3 degrees. It is a schematic front view which shows the heat sink of 2nd Embodiment, and shows the example whose opening angle (alpha) is 5 degrees. It is a schematic front view which shows the heat sink of 2nd Embodiment, and shows the example whose opening angle (alpha) is 10 degrees. It is a schematic front view which shows the heat sink of a comparative example, and shows the example whose opening angle (alpha) is 0 degree. It is a figure which shows the air velocity distribution obtained by simulation calculation when opening angle (alpha) is 2 degrees. It is a figure which shows the air velocity distribution obtained by simulation calculation when opening angle (alpha) is 3 degrees. It is a figure which shows air velocity distribution obtained by simulation calculation when opening angle (alpha) is 5 degrees. It is a figure which shows the air velocity distribution obtained by simulation calculation when opening angle (alpha) is 10 degrees. It is a figure which shows the air velocity distribution obtained by simulation calculation when opening angle (alpha) is 0 degree. It is a schematic front view which shows the heat sink of 3rd Embodiment of this invention, and shows the example whose opening angle (alpha) is 10 degrees. It is a schematic front view which shows the heat sink of a comparative example, and shows the example whose opening angle (alpha) is 0 degree. It is a schematic front view which shows a comparative heat sink, and shows the example in which the pin fin row | line | column is provided uniformly with the angle of attack (beta) of 5 degrees. It is a figure which shows the air velocity distribution obtained by simulation calculation when opening angle (alpha) is 10 degrees. It is a figure which shows the air velocity distribution obtained by simulation calculation when opening angle (alpha) is 0 degree. It is a figure which shows the air velocity distribution obtained by the simulation calculation when the angle of attack β is 5 °. It is a schematic front view which shows the heat sink of 4th Embodiment of this invention, and shows the example whose opening angle (alpha) is 10 degrees. It is a schematic front view which shows the heat sink of a comparative example, and shows the example whose opening angle (alpha) is 0 degree. It is a schematic front view which shows a comparative heat sink, and shows the example in which the pin fin row | line | column is provided uniformly with the angle of attack (beta) of 5 degrees. It is a figure which shows the air velocity distribution obtained by simulation calculation when opening angle (alpha) is 10 degrees. It is a figure which shows the air velocity distribution obtained by simulation calculation when opening angle (alpha) is 0 degree. It is a figure which shows the air velocity distribution obtained by the simulation calculation when the angle of attack β is 5 °.

The example of the form for implementing this invention is demonstrated referring drawings below.
Note that the heat sink of the present invention shown in each of the following examples is desirably manufactured using a material having good thermal conductivity such as aluminum, aluminum alloy, copper, or copper alloy.

  Further, in order to improve the cooling performance, the surface of the heat sink of the present invention may be subjected to a surface treatment that enhances heat radiation. In particular, when using a heat sink for natural air cooling, the convective heat transfer coefficient is inevitably relatively small and tends to stop, so it can be said that the contribution of the radiant heat transfer coefficient is relatively large. Therefore, increasing the radiant heat transfer coefficient is considered to be particularly effective. For example, when the material of the heat sink is aluminum or an aluminum alloy, as a method for increasing the radiant heat transfer rate, a method in which alumite treatment such as black alumite treatment is simple and possible even for complicated shapes is possible. It is preferable.

(First embodiment)
20A to 20D are schematic front views of the heat sink according to the first embodiment of the present invention, and FIG. 20E is a schematic front view of the heat sink of the comparative example.
FIG. 21 is a perspective view of the heat sink according to the first embodiment of the present invention corresponding to FIG. 20D.
The heat sink 10 of the first embodiment is for transferring heat to the cooling air on the plate surface of the base plate 1 (width 61 mm, length (height) 70 mm, plate thickness 3 mm) placed substantially vertically. A plurality of pin fins 2 (columnar shape having a diameter of 2.5 mm and a height of 25 mm) are provided upright, and the plurality of pin fins 2 are arranged in a straight line at a predetermined interval (1.8 mm). A pair of (pin fin rows) (a pair of pin fin rows) is formed so as to form an approximately V shape that opens upward, that is, between the pin fins at the row end portions of the pin fin rows vertically below each other. A plurality of pin fins 2 are erected on the plate surface of the base plate 1 so that the distance between the pin fins at the row end portions vertically above the distance is larger than the distance. In other words, in the heat sink 10, a pair of pin fin rows are arranged on the base plate 1 so as to face each other so that the space between the rows gradually expands vertically upward. In this embodiment, three pairs (that is, six pin fin rows) of a pair of pin fin rows forming a substantially V shape are arranged in the horizontal direction.

  The opening angle of the substantially V-shape (referred to as the apex angle at the tip of the substantially V-shape) α was gradually increased to 0 to 10 °. However, the example in which the opening angle α in FIG. 1E is 0 ° is shown for comparison and does not belong to the embodiment of the present invention. The opening angle α corresponds to the angle formed by the pin fin arrangement directions in the pin fin row.

  20A to 20E, the opening angle α is increased from a state in which two pin fin rows in each of three pairs (three pairs) of pin fin rows are arranged parallel to each other along the vertical direction (see FIG. 20E). This is done by rotating the pin fin rows slightly in opposite directions. Here, in order to prevent the total number of pin fins 2 arranged on the base plate 1 from changing even if the opening angle α is changed, each pin fin row is rotated around the center position in the vertical direction of the pin fin row. I made it. In this embodiment, the distance between the centers of the pair of pin fin rows in the vertical direction is 8.3 mm.

  Although not shown in FIGS. 20A to 20E, the heat generating component 3 is connected across the entire back surface of the base plate 1 (the side opposite to the side where the pin fins 2 are erected).

  In the pin fin type heat sink (α = 0 °) of the comparative example shown in FIG. 20E, the pin fin rows are arranged in parallel to each other in the vertical direction, so that the rising airflow of the warmed air flows upward as it is.

  On the other hand, in the example shown in FIGS. 20A to 20D in which the opening angle α is larger than 0 ° and has a certain opening angle, the pin fin row is inclined (α / 2) with respect to the vertical direction. It extends to. This obliquely arranged pin fin row has an angle of attack that is half the opening angle (α / 2) for a rising air flow rising in the vertical direction, so that the rising air flow of warmed air collides with the pin fin row. And it is conceivable that a part passes through the pin fin row and reaches the opposite side (inside the pair of pin fin rows). Here, this is tentatively called “attack angle impact effect”. However, when the opening angle α is small as shown in FIGS. 20A to 20D, this effect is expected to be insignificant.

  However, as will be described in detail below, there is a reason different from the “attack angle collision effect”, and even if the opening angle α is small, the pair of pin fin rows has an opening angle α of more than 0 ° vertically upward. As a result (see FIGS. 20A to 20D), more air than expected passes through the pin fin rows and reaches the opposite side as compared to when the pin fin rows are arranged in the vertical direction (see FIG. 20E). I found out.

In order to confirm that the cooling performance of the heat sink of the first embodiment is excellent, a simulation calculation was performed.
FIG. 22 shows a perspective view for explaining a calculation model used for the simulation calculation. The simulation calculation was performed for the state where the wind tunnel 3 was attached to the heat sink 10. The wind tunnel 3 has a rectangular parallelepiped shape penetrating in the vertical direction. The front, rear, left and right four surfaces are walls, and the upper and lower surfaces are open surfaces. The wind tunnel 3 is attached to positions 15 mm (a, b = 15 mm in FIG. 22) from the upper and lower ends of the heat sink 10 and 5 mm (c = 5 mm in FIG. 22) from the tip of the pin fin 2. .

  Further, since the heat sink 10 is mirror-symmetric (symmetric in FIGS. 20A to 20E), the simulation calculation was performed on one half of the mirror symmetry plane in order to shorten the calculation time. For this reason, FIG. 22 also shows one half of the heat sink 10.

  The results of the air velocity distribution obtained by the simulation calculation for each structure of FIGS. 20A to 20E are shown in FIGS. 23A to 23E. As a result of the air velocity distribution, an air velocity distribution in a vertical plane (in this embodiment, a position 12.5 mm away from the base plate 1) at a position that is 1/2 the height of the pin fin 2 is shown. In FIG. 23, the larger the air velocity, the darker the black color. The figure also shows the base plate maximum temperature rise value ΔT in each case.

  The simulation calculation conditions were a calorific value of 10 W at the heat generating portion, the wind tunnel material was resin, the heat sink material was an aluminum alloy, and the boundary condition of the lower part of the wind tunnel was an atmospheric pressure of 25 ° C.

  As can be seen from FIG. 23A to FIG. 23E, in any of the regions sandwiched between the pin fin rows, the speed increases toward the upper side. This is because the air is warmed while moving as an updraft. It is thought that this is because it is gradually accelerated by continuing to receive even greater buoyancy. In addition, since all the regions sandwiched between the pin fin rows are guarded by the pin fin rows on both the left and right sides, it can be considered that a kind of “chimney effect” occurs there.

  When carefully observed, the opening angle α gradually increases from 0 ° from FIG. 23E to FIG. 23A to FIG. 23D, and the inside of the substantially V-shaped shape that opens upward (that is, the width increases toward the top). The air velocity in the space gradually increases, and conversely, the space outside the substantially V-shape that opens upward, that is, the inside of the substantially V-shape that opens downward (that is, the space becomes narrower as it goes upward). It can be seen that the air velocity in the space gradually decreases.

  That is, when the opening angle α is not 0 °, the air velocity is different between the inside and the outside of the substantially V shape that opens upward. In general, pressure drops when air flows at high speed (Bernoulli's theorem). Accordingly, the degree of pressure drop based on the flow of air at a high speed is also different, and the pressure drop is more remarkable on the inner side of the substantially V-shape opening upward than on the outer side. As a result, a pressure difference is generated between the inside and outside of the substantially V shape, and a force is applied so that air is drawn in from the outside toward the inside.

  As apparent from the above description, this effect does not occur when the opening angle α is 0 °, but only occurs when the opening angle α is greater than 0 °. This will be called the “difference effect”.

  In addition to the chimney effect, in addition to the chimney effect, the air flows more rapidly as it goes upward in the space portion inside the substantially V-shape that opens upward as described above. This is probably because the fluid friction resistance becomes smaller as the air rises because the flow path becomes wider. Moreover, the extent of the spread is proportional to the size of the opening angle α. As a result, as shown in FIGS. 23A to 23D, it is considered that the air velocity increases as the opening angle α increases.

  On the other hand, in the outer portion of the substantially V-shape that opens upward (that is, the inner portion of the substantially V-shape that opens downward), the air flows more slowly as it goes upward in the opposite direction. It is considered that the fluid friction resistance increases as the air rises because the flow path narrows in a tapered shape as it goes upward. Moreover, the degree of the narrowing is proportional to the size of the opening angle α. As a result, as shown in FIGS. 23A to 23D, it is considered that the air velocity gradually decreases as the opening angle α increases.

  In the first embodiment, a case is shown in which three pairs of pin fin rows constituting a substantially V-shape opening upward are provided in the horizontal direction. However, as can be understood from the above description, “open” The “angular pressure differential effect” occurs even when there is only one pair of pin fin rows constituting a substantially V-shape that opens upward. That is, in the inner space portion of the approximately V-shape that opens upward, the flow path becomes wider toward the upper side and the air flows at a higher speed as it goes upward as described above. Since there is no such effect in the space portion outside the V shape, the air velocity is larger on the inside than on the outside of the substantially V shape.

  Even if the opening angle α is 0 °, the so-called “chimney effect” is considered to occur. Briefly, the “chimney effect” is mainly related to the air movement in the vertical direction (the direction along the pin fin array), while the “open angle pressure difference effect” is mainly the air movement in the horizontal direction (the direction across the pin fin array). It can be said that.

  Due to the presence of this “opening angle pressure differential effect”, air passes better than expected even at a narrow interval between the pin fins constituting the pin fin row. Therefore, heat is efficiently exchanged between the pin fins and air, and the cooling performance is excellent.

From the air velocity distribution shown in FIGS. 23A to 23E, this “opening angle pressure difference effect” begins to appear even when the opening angle α is slightly increased from 0 °, and becomes gradually more pronounced as the opening angle α increases. It turns out that it becomes an effect.
Further, from the result of the maximum temperature rise value ΔT of the base plate 1 shown in FIGS. 23A to 23E, in the arrangement of the pin fins 2 shown in FIG. 20, a change in ΔT is clearly seen when α = 2 °, and α It can be seen that when T = 5 °, the change in ΔT is obvious.

(Second Embodiment)
24A to 24D are schematic front views of the heat sink according to the second embodiment of the present invention, and FIG. 24E is a schematic front view of the heat sink of the comparative example.
In the heat sink of the second embodiment, the distance between the pin fins in the pin fin row is larger than that of the first embodiment. However, other points are almost the same as those of the heat sink of the first embodiment.

  The heat sink according to the second embodiment includes a plurality of heat exchangers for transferring heat to the cooling air on the plate surface of the base plate 1 (width 85 mm, length (height) 70 mm, plate thickness 3 mm) placed substantially vertically. The pin fins 2 (columnar shape with a diameter of 4.2 mm and a height of 25 mm) are erected, and the plurality of pin fins are arranged in rows (9 mm) at a predetermined interval (9 mm). A pair of pin fin rows) (a pair of pin fin rows) is formed so as to form a substantially V-shape that opens upward, that is, the distance between the pin fins at the row end portions of the pair of pin fin rows vertically below each other. A plurality of pin fins 2 are erected on the base plate 1 so that the distance between the pin fins at the end of the row in the vertical upper direction is larger than that of the base plate 1. In the second embodiment, as in the first embodiment, three pairs of pin fin rows that form a substantially V-shape are arranged in the horizontal direction (that is, six pin fin rows).

  In the method of increasing the opening angle α in FIGS. 24A to 24E, each pin fin row is rotated around the center position of the pin fin row as in the first embodiment. In this embodiment, the pair of pin fin rows is assumed to have a distance of 10 mm between the centers in the vertical direction.

  The results of the air velocity distribution obtained by the simulation calculation for each structure of FIGS. 24A to 24E are shown in FIGS. 25A to 25E. The figure also shows the base plate maximum temperature rise value ΔT in each case. The simulation calculation conditions are the same as in the first embodiment.

  As can be seen from FIGS. 25A to 25E, in the heat sink of the second embodiment, as in the heat sink of the first embodiment described with reference to FIGS. 23A to 23E, in any of the regions sandwiched between the pin fin rows. The speed of air increases in the upward direction, and as the opening angle α gradually increases from 0 °, the air velocity in the space inside the generally V-shaped shape that opens upward (that is, increases in the upward direction) is The air velocity of the inner space (the outer space of the approximately V-shape that opens upward) inside the approximately V-shape that gradually increases and conversely opens downward (that is, narrows as it goes upward) is It is getting smaller.

From the transition state of the air velocity distribution shown in FIGS. 25A to 25E, the “opening angle pressure difference effect” begins to appear even when the opening angle α is slightly increased from 0 °, and as the opening angle α increases. It turns out that it becomes a remarkable effect gradually.
Further, from the result of the maximum temperature rise value ΔT of the base plate 1 shown in FIGS. 25A to 25E, in the case of the arrangement of the pin fins 2 shown in FIG. 24, a change in ΔT is clearly seen when α = 5 °. And when α = 10 °, it can be seen that the change in ΔT is obvious.

As described above, in both the first embodiment and the second embodiment, the “opening angle pressure difference effect” occurs even when the opening angle α is slightly increased from 0 °.
In the first embodiment, the maximum temperature rise value ΔT of the base plate 1 is clearly changed even when α = 2 °. The change in ΔT is obvious when α = 5 °, and α = 5 in the second embodiment. There is a clear change in ΔT at °, and the change in ΔT is obvious when α = 10 °.

  As can be seen from the heat sink 10 shown in FIGS. 20A to 20E and the heat sink 10 shown in FIGS. 24A to 24E, the value of the opening angle α where the change in ΔT is obvious is the value of each specific heat sink (ie, pin fin). Depending on the structure of the column). However, from the above results, it can be said that the performance of the heat sink is improved at least at α = 2 °, further improved at α = 5 °, and further improved at α = 10 °.

  It should be noted that, as explained above, the “opening angle pressure difference effect” occurs because the pin fin array has “opening angle”. Therefore, for example, even if each pin fin row is arranged in an oblique direction with an angle β (hereinafter referred to as “attack angle”) β with respect to the vertical direction, the adjacent pin fin row similarly has an angle of attack β. If the pin fin rows are arranged in an oblique direction and are parallel to each other (that is, the opening angle α = 0 °), it is expected that the “opening angle pressure difference effect” does not occur.

The result of confirming this is shown below.
26A and 26B are the same as FIGS. 20D and 20E described above, and the opening angle α is 10 ° and 0 °, respectively. From another perspective, FIG. 26A can also be seen as pin fin rows having angles of attack β = 5 ° and β = −5 ° arranged alternately.
On the other hand, FIG. 26C is a diagram in which the pin fin row of β = −5 ° in FIG. 26A is rotated 10 ° to the + β side and arranged on the β = 5 ° side. That is, all pin fin rows correspond to those arranged parallel to each other with an angle of attack β = 5 °.

  FIGS. 27A to 27C show the results of air velocity distribution obtained by simulation calculation for each structure of FIGS. 26A to 26C. The figure also shows the base plate maximum temperature rise value ΔT in each case. The simulation calculation conditions are the same as in the first embodiment.

As can be seen from FIGS. 27A to 27C, when the angle of attack β of all the pin fin rows shown in FIG. 27C is 5 °, the pin fin rows shown in FIG. is almost equal to α = 0 °. That is, as described above, it is understood that the “opening angle pressure difference effect” does not occur in such a case.
In addition, the fact that the angle of attack β of all the pin fin rows shown in FIG. 27C is 5 ° and the one where the pin fin rows shown in FIG. 27B are along the vertical direction are almost equal to each other. "Collision effect" means that it is not so much affected, or very little if any.

  Moreover, what was similarly examined with respect to the heat sink of 2nd Embodiment is shown to FIG. 28A-FIG. 28C and FIG. 29A-FIG. 29C. As shown in FIG. 29A to FIG. 29C, the heat sink of the second embodiment has the same results as those studied for the heat sink of the first embodiment shown in FIG. 27A to FIG. 27C. It was confirmed that no “opening angle pressure difference effect” was observed in FIG. 29C in which the pin fin rows of FIG. 29 were arranged parallel to each other with an angle of attack β = 5 °.

(Third embodiment)
1A and 1B are a perspective view and a front view showing a heat sink according to a third embodiment of the present invention.
The heat sink of the third embodiment of the present invention transfers heat to the cooling air on the plate surface of the base plate 1 (width 35 mm, length (= height) 70 mm, plate thickness 3 mm) placed substantially vertically. A plurality of pin fins 2 (columnar shape with a diameter of 2.5 mm and a height of 25 mm) are erected, and the plurality of pin fins are arranged linearly at predetermined intervals of 1.8 mm. The pair of rows is erected on the plate surface of the base plate 1 so as to form a substantially V-shape that opens upward.

  Here, the plurality of pin fins 2 may be provided in a complete V shape with the V-shaped tips closed. However, for example, in order to use the die casting method as a method of standing the pin fins 2 on the base plate 1, it is necessary that the space between the pin fins 2 is about 2 mm, and as shown in FIG. May be easier to manufacture if there is a little (for example, 2 mm). Further, when the lower ends of the two pin fin rows are separated from each other in this way, it is possible to perform a simulation on a region on one side with respect to the symmetry line, and the design of the heat sink becomes easy. For this reason, in this embodiment, the lower ends of the two pin fin rows are assumed to be slightly separated from each other. Further, the opening angle α of the substantially V-shape formed by the pair of pin fin rows was 20 °.

  Although the heat generating component 3 (width 20 mm, length (= height) 20 mm) is not shown in FIGS. 1A and 1B, the back side of the base plate 1 (the side opposite to the side where the pin fins 2 are erected). ) Is connected to almost the center.

It was confirmed by simulation calculation that the heat sink of the third embodiment has excellent cooling performance. The result will be specifically described.
For comparison, a simulation calculation was also performed for a heat sink in which pin fins were uniformly distributed as shown in the perspective and front views of FIGS. 2A and 2B. For comparison, these heat sinks are provided with the same total number of pin fins having the same cross-sectional shape and the same fin height so as to have the same weight.

  FIG. 3 is a perspective view illustrating a calculation model used for the simulation calculation. The simulation calculation was performed for the state where the wind tunnel 3 was attached to the heat sink 10. Although the wind tunnel 3 has a rectangular parallelepiped shape, only the four surfaces on the front, rear, left, and right sides are walls, and the two upper and lower surfaces are hollow. The wind tunnel 3 was attached to positions 15 mm (a and b in FIG. 3) from the upper and lower ends of the heat sink 10 and 5 mm (c in FIG. 3) from the tip of the pin fin.

  Further, since the heat sink 10 has mirror symmetry, since the simulation calculation is performed for one half of the mirror symmetry plane in order to shorten the calculation time, FIG. 3 also shows one half of the heat sink.

  The conditions for the simulation calculation were a heating value of 10 W at the heat generating part, the wind tunnel material was resin, the heat sink material was an aluminum alloy, and the boundary condition of the lower part of the wind tunnel was an atmospheric pressure of 25 ° C.

  The simulation calculation results are as follows. The maximum temperature rise ΔT of the base plate is 75.3 ° C. in the heat sink of the comparative example, whereas it is 72.4 ° C. in the heat sink of the third embodiment of the present invention, which is the third embodiment of the present invention. It can be seen that the cooling performance is excellent.

  Consider the reason. 4A and 4B show the air velocity distribution in the vertical plane at a position 1/2 of the pin fin height. In FIGS. 4A and 4B, the larger the air velocity, the darker the black color. From FIG. 4A, it can be seen that in the pin fin arrangement of the comparative example, the air flow is blocked by the pin fins scattered vertically and horizontally, the resistance is large, and the speed does not increase.

  On the other hand, it can be seen from FIG. 4B that in the heat sink of the third embodiment of the present invention, air flows at a high speed inside the substantially V-shape. This is considered to be caused by the following. That is, heat is released from the base plate 1 around which the heat generating component is connected to the back side, so that the air around the base plate 1 is warmed and an upward air flow is generated. The ascending air current first collides with the pin fins 2 and then passes through the gap between the pin fins 2 and then reaches the inner side of the substantially V-shape to ascend the space. The ascending air flow gradually increases in response to buoyancy. Furthermore, since the inside of the substantially V shape is a free space, there is no flow resistance due to the pin fins scattered vertically and horizontally as in the comparative example. Furthermore, the inner side of the substantially V-shape is opened as a free space above and the left and right sides are guarded by linearly arranged pin fins constituting the substantially V-shape. Therefore, it is considered that a kind of “chimney effect” occurs, and the flow of air that rises due to buoyancy is accelerated further and flows upward at high speed.

  Since the pressure decreases when the air in the space (inside the substantially V shape) flows upward at high speed, the air outside the substantially V shape is drawn toward the inside of the substantially V shape. It will be. Here, since the V-shaped tip of the heat sink is substantially closed, air mainly flows through the gap between the pin fins. Of course, since the air velocity is larger on the inner side of the substantially V shape than on the outer side, the aforementioned “opening angle pressure difference effect” also acts. That is, the momentum of the air passing through the gap between the pin fins arranged linearly so as to form a substantially V shape is further increased. Due to the presence of these effects, air can pass better even if the distance between the pin fins is narrow. Therefore, in the third embodiment of the present invention, the heat is efficiently exchanged between the pin fins and the air for cooling. It is thought that the performance will be excellent.

  Now, assuming that the "chimney effect" is generated inside the substantially V-shape based on the guard effect of the linearly arranged pin fin as described above, it is considered that the effectiveness of the guard effect is determined. The size of the substantially V-shaped opening angle α is considered to have a great influence on the cooling performance of the heat sink of the present invention.

  Therefore, in order to investigate the effect of the opening angle α of the substantially V shape, the case where α is changed from 10 ° → 15 ° → 20 ° → 25 ° → 30 ° → 40 ° → 50 ° is examined by simulation calculation. did. The given conditions for the simulation calculation were the same as those in FIGS. However, the base plate dimensions were set to a width of 70 mm, a length (= height) of 70 mm, and a thickness of 3 mm so that the pin fin arrangement does not protrude from the base plate even when the opening angle α of the substantially V shape is increased.

  The obtained results are shown in FIG. 5 as the relationship between the opening angle α and the maximum temperature rise value ΔT of the base plate. Moreover, the state of the air velocity distribution at each opening angle α is shown in FIGS.

  As apparent from FIGS. 6 to 8, as α increases from 10 ° → 15 ° → 20 °, the air passes through the gap between the pin fins arranged linearly so as to form a substantially V shape. It is extremely noticeable that the momentum of this has gradually increased. This is because the width of the inner region of the substantially V-shaped where the “chimney effect” occurs gradually becomes wider and the air easily flows, the “chimney effect” itself becomes stronger, and the updraft flows upward at a higher speed. This is considered to mean that the momentum of the air outside the substantially V-shape is drawn toward the inside of the V-shape is increased. Correspondingly, as can be seen from FIG. 5, as α increases from 10 ° → 15 ° → 20 °, ΔT significantly decreases and the cooling performance is improved.

  On the other hand, it can be seen from FIG. 5 that when the opening angle α exceeds 20 °, ΔT gradually increases and the cooling performance decreases. 9 to 12 corresponding to this, when α is 25 ° or more, a region having a low air velocity (a whitish portion in these drawings) appears above the inside of the substantially V shape. I understand that. Then, as the angle increases from 25 ° → 30 ° → 40 ° → 50 °, this region steadily expands, and when α = 50 °, the region where the air velocity is low occupies almost the entire inside of the V shape. . This is considered to be because if the opening angle α is too wide, it is no longer “chimney” -like and the “chimney effect” is weakened. Therefore, α needs to be 40 ° or less. From the above, in this embodiment in which the tip of the V-shape is closed, it can be said that the opening angle α of the substantially V-shape is preferably 10 ° <α ≦ 40 °.

It can be seen that if the opening angle α is selected as 15 ° ≦ α ≦ 30 °, the air velocity is generally high and ΔT can be kept low, which is preferable.
When α is small, when the substantially V-shape is arranged, for example, at the center of the base plate, there will be regions where no pin fins are present on both sides of the base plate. In such a case, in order to further improve the cooling performance, the substantially V-shaped shape is also arranged side by side on both side regions so that the substantially V-shaped pin fin arrangement is repeatedly provided twice or more in the horizontal direction. Is preferred.

By the way, as described above, in the heat sink of the present invention, the flow of air passing through the gap between the pin fins arranged linearly so as to form the substantially V shape is important. Then, next, how the cooling performance changes when the size of the gap between the pin fins is changed in the third embodiment of the present invention was specifically examined by simulation calculation.
The base plate dimensions were set to a width of 70 mm, a length (= height) of 70 mm, and a plate thickness of 3 mm as in the above examination. The opening angle α was set to 20 °, which was the best cooling performance in the above examination. When the opening angle α is set to 20 °, a region where no pin fins exist in the base plate having the above dimensions is generated. Therefore, a study was made on a shape in which two substantially V-shaped pin fins are arranged in the horizontal direction. Since the gap between the pin fins is changed on the base plate having a predetermined dimension, the number of pin fins was changed in accordance with the size of the gap.

  The examination results are shown in FIGS. 13 and 14A to 14C. FIG. 13 shows the relationship between the pin fin gap and the maximum temperature rise value ΔT of the base plate. From now on, there is an appropriate size in the gap between the pin fins, and the cooling performance is good even if it is too large or too small. You can see that it is inferior. Here, when the gap is 2.5 mm, ΔT is 46.8 ° C., which is the highest characteristic.

Looking at the simulation results of the air velocity distribution shown in FIGS. 14A to 14C, the air velocity is clearly slower in the gap of 1.25 mm shown in FIG. 14A both inside the pin fin gap and inside the V shape. I understand. When the gap between the pin fins becomes smaller in this way, it is difficult for air to pass through the gap, so that the cooling performance may be deteriorated.
On the other hand, as shown in FIG. 14B and FIG. 14C, the reason why the cooling performance becomes inferior when the pin fin interval is increased is that the total number of pin fins that can be erected on the base plate of a predetermined size is reduced and the total heat radiation area This is thought to be due to the decrease in

  From the consideration of the effect of the pin fin gap described above on the cooling performance, the following can be said. That is, in terms of the total number of pin fins that can be erected on a base plate having a predetermined dimension, the pin fin gap is preferably as small as possible. However, as the pin fin gap becomes smaller, there is a problem that the cooling performance becomes inferior because air becomes difficult to pass through. Therefore, if the total number of pin fins to be erected on the base plate of a predetermined dimension, for example, the pin fin erection position, is maintained and the difficulty of air passage can be improved, the cooling performance can be improved. It becomes possible to raise.

  As one means for realizing this, for example, if the cross-sectional shape of each pin fin (the cross-sectional shape perpendicular to the longitudinal direction) is a circle, compared to the case where it is a quadrangle, Air becomes easier to pass through the gap between the pin fins more smoothly. In this way, even if the arrangement position of each pin fin and the size of the cross-sectional area of each pin fin are the same, that is, the total number and the total weight of the entire pin fin are the same, the cooling performance is further improved.

  Furthermore, it is conceivable to change the cross-sectional shape of each pin fin from a circular shape to an elliptical shape extending along the air flow direction while maintaining the standing position of the pin fin. That is, the shape is changed to an ellipse in which the direction connecting the outer side and the inner side of the substantially V-shaped is the major axis and the direction along the substantially V-shaped pin fin row is the minor axis. Then, compared with the case where it is circular, the gap between the pin fins is further widened so that air can pass more easily, and the contact distance between the air and the pin fin when the air passes through the gap between the pin fins That is, since the contact area is increased, the cooling performance is further improved.

  However, the directions of the major axis and the minor axis described above do not necessarily exactly coincide with the “direction connecting the outer side and the inner side of the substantially V-shaped” and the “direction along the substantially V-shaped pin fin row”. In order to facilitate the smooth passage of air (upward airflow) through the substantially V-shaped pin fin row, rather, the long axis is obliquely crossing the “direction along the substantially V-shaped pin fin row”, that is, substantially V-shaped. It can be said that it is more preferable to be arranged so as to be inclined from the outer vertical lower side toward the inner vertical upper side.

Then, the case where the aspect ratio was changed by changing the cross-sectional shape of the pin fin from a circular shape to a gradually elongated elliptical shape was examined by simulation calculation. At this time, the standing position (cross-sectional center position) of each pin fin is maintained and the cross-sectional shape of each pin fin is gradually changed from a circular shape to an elongated elliptical shape so that only the change accompanying the ovalization can be grasped as purely as possible. At this time, the size of the cross-sectional area itself was kept the same so that the total number and weight of the entire pin fins were kept the same.
Further, as a circular pin fin as a starting point, a gap 1.8 mm (ΔT = 47.4) which is narrower than a gap 2.5 mm (ΔT = 46.8 ° C.) obtained with the highest characteristics in the examination of FIG. C) was selected.

  The result obtained by the above simulation calculation is shown in FIG. 15 as the relationship between the aspect ratio and the maximum temperature rise value ΔT of the base plate. FIG. 16 shows the air velocity distribution when the aspect ratio is 3.26 and 4.82.

From FIG. 15, starting from a circle (aspect ratio of 1.00), the aspect ratio is increased and gradually becomes elliptical, so that ΔT decreases significantly and the cooling performance is steadily improving. I understand. This is thought to be due to the fact that as the aspect ratio is increased, the gap between the pin fins is expanded and the air is more easily passed, and the contact area between the air and the pin fin is increased when the air passes through the gap between the pin fins. .
Even when the aspect ratio is 1.44 (major axis 3.0 mm, minor axis 2.1 mm), ΔT = 45.6 ° C., and the highest characteristic (ΔT = 46.8 ° C.) obtained in FIG. It is amazing that it is far greater.

  However, the degree of improvement in characteristics gradually becomes gradual, and ΔT = 43.5 ° C. obtained with an aspect ratio of 3.26 (major axis 4.5 mm, minor axis 1.4 mm) is the highest characteristic, and thereafter the characteristic gradually increases. Decreases.

  16A and 16B show the state of air velocity distribution when the aspect ratio is 3.26 and 4.82, but the latter (aspect ratio 4.82) is compared to the former (aspect ratio 3.26). It can be seen that there are many lighter portions near the fins, that is, the air velocity is slower. Thus, as the aspect ratio increases, the pin fins gradually become plate-like fins, and the contact distance between the air and the pin fins when the air passes through the gaps between the pin fins becomes too long, resulting in cooling. It is considered that the flow rate of the working air is lowered and the cooling performance is lowered.

  In the above examination, the pin fin has an elliptical cross-sectional shape. However, in addition to the elliptical shape, the gap between the pin fins is widened to facilitate the passage of air and the pin fins when the air passes through the gap between the pin fins. Needless to say, it may have a shape that is expected to increase the contact area between the air and the air, for example, streamline, leaf shape, or egg shape.

  The reason why the cooling performance is excellent in the heat sink of the third embodiment of the present invention has been described above. Here, the key points that are the main points are examined and discussed, and each prior art document listed above is used. Organize the differences.

In a natural air cooling heat sink, it is most important to devise so that the flow of cooling air is accelerated and enhanced, but in this embodiment,
-(2) “Pin fins” are erected on the base plate so as to constitute (1) “substantially V-shaped”.
-And the base plate is (3) "substantially vertical",
It is realized by creating a momentum of updraft in the air by creating a kind of “chimney effect” by the two propositions. And there are three key points which are the main points in the above (1) (2) (3).

The reason why (1), (2) and (3) are key points is as follows.
First, regarding (1) “substantially V-shaped arrangement”, this arrangement is the root cause of the “chimney effect” described above.

  Next, regarding (2) “pin fin”, “natural air cooling” has the following problems with “plate fins”. As mentioned above, although the momentum of the air passing through the gap between the pin fins becomes stronger due to the “chimney effect”, in “natural air cooling”, it is derived from only the rising airflow of the heated air after all, There is a limit naturally. Therefore, for example, if the fins are plate-like, unlike the “forced air cooling” using a fan, the flow resistance when passing through the gap between the fins is too large and the momentum of the air is lost. Even if it is “natural air cooling”, the “chimney effect” can be enjoyed only if the fins are “pin fins”.

In addition, regarding (3) “vertical”, it is not necessary to explain the necessity of placing the base plate in “vertical” in order to expect “natural air cooling” by convection.
On the other hand, many heat sinks that place the base plate “horizontally” require a “forced air cooling” device such as a fan. In that case, if “pin fins” are used as fins, the air flow Since the fin density is too sparse and the efficiency is poor compared to the strength of the plate, it is rather preferable to use “plate fins”.
As described above, effective natural air cooling can be produced in the third embodiment of the present invention only when the above three factors (1), (2), and (3) are satisfied. It is necessary to remember that.

  Here, the difference between the heat sink of the embodiment of the present invention and the heat sink shown in Patent Documents 1 to 5 will be described.

  Patent Document 1 is different from the present invention using pin fins in that plate fins are used first.

  Further, FIG. 4 of Patent Document 1 shows a shape like a substantially V-shape that opens upward, and at first glance, the bag may be mistaken as if it is similar to the embodiment of the present invention. . However, the substantially V-shape shown in Patent Document 1 actually relates to the direction of each individual plate-like fin, and is arranged as an assembly of fins as in the embodiment of the present invention. In the first place, they are completely different. In addition, Patent Document 1 adopts such a direction of the fin in that the rising air collides with the fin and a turbulent flow is generated there. This is fundamentally different from the embodiment of the present invention which is intended to produce an “open angle pressure differential effect” or “chimney effect” by making the body substantially V-shaped.

  Moreover, patent document 2-patent document 4 differ from embodiment of this invention using a pin fin by the point which uses a plate-shaped fin first. Furthermore, Patent Document 2 to Patent Document 4 have no description or suggestion that the arrangement of the fins as an aggregate is a substantially V-shape that opens upward as in the embodiment of the present invention. It is fundamentally different from the embodiment of the invention.

  The heat sink of Patent Document 4 has an inclination angle so that the fin group is closed upward, whereas the heat sink according to the embodiment of the present invention has the fin group directed upward. The two have an opening angle so that the two are completely opposite in concept and structure.

  Next, in Patent Document 5, FIG. 8 shows a heat exchanger (heat sink) in which a plurality of plate-like fins are arranged in a square shape at predetermined intervals in the vertical direction on the base plate portion. .

  However, Patent Document 5 is also different from the embodiment of the present invention using pin fins in that plate fins are used. That is, Patent Document 5 has a “fin portion” as an indispensable constituent element as can be seen from the description in each claim. "Part" means the whole of a plurality of "plate fins" 3 arranged in a row in the vertical direction as shown in FIG. 1. " Yes, Patent Document 5 relates to “plate fins”.

  Further, as is apparent from the description in each claim and “Means for Solving the Problems”, Patent Document 5 describes that “to increase heat dissipation efficiency, the distance between the plate fins, the plate, It is necessary to appropriately regulate the relationship between the length of the fins and the flow velocity of the cooling air flowing between the plate fins "(paragraph 0008), and" lowering the flow velocity of the cooling air flowing between the plate fins, In order to achieve the "temperature boundary layer ... overlap" (paragraph 0007), the plate-like fins "so that the cooling air" decelerates "between the fins and flows almost uniformly" (Each claim).

  That is, Patent Document 5 is “to reduce the flow velocity of cooling air” flowing between “plate fins”, and the cooling air is “decelerated” between the fins so that it flows almost uniformly. It is a heat sink. In fact, all the embodiments described and “Best Mode for Carrying Out the Invention” are all described for “plate-like fins”, and cooling between the fins is performed. It is just what the working air "decelerates" and flows almost uniformly.

  However, in “natural air cooling” heat sinks, the problem is often that the flow rate of cooling air is rather low. Therefore, in the “natural air cooling” heat sink, contrary to the heat sink disclosed in Patent Document 5, it is the actual situation that how to increase the flow velocity is the actual situation. Was born out of the progress of study toward such a goal. That is, the direction of the embodiment of the present invention and Patent Document 5 are completely opposite in the first place, and both are essentially different.

  In other words, in the heat sink disclosed in Patent Document 5, the flow rate of the cooling air flowing into the fins is originally considerably high as long as the flow rate of the cooling air flowing between the fins is intentionally lowered as described above. To do. This is combined with the description of “inlet part for feeding cooling air” written in each claim, and the invention of Patent Document 5 assumes a forced cooling heat sink using a fan or the like. Is strongly suggested.

  In addition, although described in paragraph 0057 of Patent Document 5, “the heat exchanger of the present invention can be applied to both“ natural air cooling ”and water-cooled heat exchangers”, it is described above. In addition, the heat exchanger (heat sink) shown in Patent Document 5 is completely opposite to the direction that the “natural air cooling” heat sink should aim. Those who have ordinary knowledge in the technical field are very skeptical about using the heat exchanger (heat sink) shown in Patent Document 5 as that for “natural air cooling”.

Further, in the case of the C-shaped heat sink shown in Patent Document 5, as can be seen from Claim 4 and FIG. 9, the C-shaped heat sink arranged so as to become gradually narrower from the inlet portion toward the discharge port. It is. As is apparent from FIG. 9, this has a structure corresponding to feeding cooling air.
On the other hand, in the heat sink of the embodiment of the present invention, on the contrary, it has a substantially V shape that opens upward (that is, corresponding to the above-mentioned “discharge port”). This is a structure corresponding to utilizing the ascending air current and the “chimney effect” inside the substantially V-shape as described above in the cooling mechanism of the embodiment of the present invention.
Thus, even if it is the fin arrangement (C-shape, substantially V-shape) that looks similar at first glance, Patent Document 5 and the embodiment of the present invention have very different functions and operations.

  That is, as discussed in detail above, although Patent Document 5 and the embodiment of the present invention have a face that seems to be equivalent at first glance, their essence is quite different in many respects. There are even aspects in which they are different and the direction in which they are directed is rather reversed.

(Fourth embodiment)
FIG. 17 is a front view showing a heat sink according to a fourth embodiment of the present invention. Compared with the third embodiment of the present invention, the substantially V-shaped shape that opens upward is composed of a pair of rows in which pin fins are arranged in a convex curve shape toward the left and right outer sides. Different. Thus, the linear arrangement of the pin fins forming the substantially V shape does not necessarily have to be linear, and may be curved. In particular, as shown in FIG. 17, a curved shape convex toward the left and right outer sides is preferable because the inner side of the substantially V shape matches the “chimney effect”.
Here, the cross-sectional shape of the pin fin is circular.

(Fifth embodiment)
FIG. 18 is a front view showing a heat sink according to a fifth embodiment of the present invention. The point that the substantially V-shape opening upward is composed of a pair of rows in which pin fins are arranged in a convex curve shape toward the inside of the V-shape and the third embodiment of the present invention. Compared to different. The cross-sectional shape of the pin fin is also circular here.

(Sixth embodiment)
FIG. 19 is a front view showing a heat sink according to a sixth embodiment of the present invention, in which the substantially V-shaped pin fin arrangement of the third embodiment is arranged twice in the horizontal direction. Here, the cross-sectional shape of the pin fin is an ellipse.
From the results of FIG. 5 described above, it has been found that the opening angle α of the substantially V shape is preferably 10 ° <α ≦ 40 °, and preferably 15 ° ≦ α ≦ 30 °. For example, when the angle is large, the base plate cannot be entirely covered with such an acute V-shaped arrangement. At that time, if a plurality of substantially V-shaped pin fin arrangements are repeatedly arranged in the horizontal direction as in the sixth embodiment, an acute-angled substantially V-shaped arrangement such that the opening angle α falls within the above range is achieved. Can be used to cover the entire base plate.

  For example, as in the first embodiment, the second embodiment, and the sixth embodiment, the substantially V-shaped pin fin arrangement that opens upward is repeatedly arranged in the horizontal direction. The V-shaped pin fin arrangements are not immediately adjacent to each other, but different V-shaped pin fin arrangements different from each other may be adjacent to each other, or one V-shaped pin fin arrangement and another V-shaped pin fin arrangement. An arrangement in which a parallel row of pin fins (i.e., corresponding to a substantially V-shaped opening angle α = 0 °) is sandwiched between the U-shaped pin fin arrangements.

  Moreover, you may make it provide the substantially V-shaped pin fin arrangement | positioning opened upwards repeatedly in the perpendicular direction twice or more.

  The heat sink according to the present invention can be used to cool the heating elements of various devices including electronic devices by natural air cooling. Since high cooling performance can be realized only by natural air cooling without using a cooling fan, it is particularly suitable for use in applications where there is a strong demand for weight reduction such as for automobiles.

1 Base plate 2 Pin fin 3 Wind tunnel 10 Heat sink

Claims (12)

A heat sink used to cool a cooling object,
A base plate erected so that an updraft generated by heat generated from the object to be cooled flows along the plate surface;
A pin fin group comprising a plurality of pin fins disposed on the plate surface of the base plate;
With
The pin fin group has a pair of pin fin rows in which a plurality of pin fins are arranged in a row at intervals from each other, and the pair of pin fin rows gradually spreads vertically between the rows. Arranged opposite to the horizontal direction,
A heat sink characterized by that.   The heat sink according to claim 1, wherein a cross-sectional shape of the plurality of pin fins is circular or elliptical.   The heat sink according to claim 2, wherein a cross-sectional shape of the plurality of pin fins is a circle or an ellipse having an aspect ratio of 1.0 to 5.0.   4. The heat sink according to claim 2, wherein a cross-sectional shape of the plurality of pin fins is an ellipse that is long from an outer vertical lower side to an inner vertical upper side of the pair of pin fin rows.   5. The heat sink according to claim 1, wherein in the pin fin group, the pair of pin fin rows is repeatedly provided in two or more pairs in the horizontal direction.   6. The heat sink according to claim 1, wherein the pair of pin fin rows has an angle formed by arrangement directions of pin fins in each pin fin row of 40 ° or less. A base plate and a pin fin group comprising a plurality of pin fins disposed on the plate surface of the base plate, the pin fin group having a pair of pin fin rows in which a plurality of pin fins are arranged in a row at intervals from each other The pair of pin fin rows is a method of using a heat sink disposed so as to face each other so as to gradually spread between the rows,
Ascending airflow generated by the heat generated from the cooling target flows along the plate surface of the base plate, and the pair of pin fin rows face each other in the horizontal direction so that the space between the rows gradually spreads vertically upward. In addition, the heat sink is arranged and used for natural air cooling,
A method of using a heat sink.   The method of using a heat sink according to claim 7, wherein a cross-sectional shape of the plurality of pin fins is circular or elliptical.   The method of using a heat sink according to claim 8, wherein a cross-sectional shape of the plurality of pin fins is a circle or an ellipse having an aspect ratio of 1.0 to 5.0.   10. The method of using a heat sink according to claim 8, wherein a cross-sectional shape of the plurality of pin fins is an ellipse that is long in a direction crossing an arrangement direction of the pin fins in the pin fin row. In the pin fin group, two or more pairs of the pin fin rows are provided,
The method of using a heat sink according to any one of claims 7 to 10, wherein the heat sink is arranged so that the pair of pin fin rows is repeatedly arranged in two or more pairs in the horizontal direction.   The method of using a heat sink according to any one of claims 7 to 11, wherein the pair of pin fin rows has an angle formed by pin fin arrangement directions in each pin fin row of 40 ° or less.