JP2004047789A - Heat sink - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heat sink wherein pressure loss of cooling fluid is little even if cooling air of large capacity and high speed is used, cooling capability is superior and an electronic element having large caloric value can be cooled with high efficiency, in the heat sink which is provided with a substrate and a plurality of vertical fins held by the substrate. <P>SOLUTION: The heat sink is provided with the substrate wherein a heat generating element is bonded on the back, and fins wherein the plurality of vertical fins disposed upright on the substrate are arranged. Thickness and height of the vertical fins are increased, heat exchange area is ensured, and dimensions of the respective parts are made a specified relation. As a result, structure is obtained wherein pressure loss of cooling air is restrained low. <P>COPYRIGHT: (C)2004,JPO

Description

【００２５】
【表２】

【００２６】
（比較例）
比較のため、図１０に示す各部構造を有し、表３に示す各フィン寸法を有するヒートシンクを作成し、実施例と同様にして放熱実験をして性能を評価した。測定結果を表３に併記した。
【００２７】
【表３】

【００２８】
表１から表３の結果から、本発明によれば高発熱量の素子を接合したヒートシンクにおいて、風速を高めても格子状のフィン内での圧力損失を低く抑え、効率的な素子の放熱が行われるので、素子の性能を最大限に発揮できることが判る。
【００２９】
【発明の効果】
本発明によれば、冷却流体がフィン体に当ったときの通風抵抗（圧力損失）の上昇を抑え、十分な冷却流体をヒートシンク本体内に呼び込んで冷却効率を向上させることができるので、特に車両の制御機器のように設置する空間が限られ、しかも多量の熱を発生する制御素子の温度制御に有効である。
【図面の簡単な説明】
【図１】本発明のヒートシンクの構造を説明する外観斜視図である。
【図２】図１のヒートシンクの線Ａ−Ａ’に沿った断面図である。
【図３】図１のヒートシンクの線Ｂ−Ｂ’に沿った断面図である。
【図４】縦フィンの構造を示す断面図である。
【図５】図４の一部を拡大して示した図である。
【図６】縦フィンの板厚と素子の温度上昇及び圧力損失との関係を示す図である。
【図７】フィンの高さと素子の温度上昇及び圧力損失との関係を示す図である。
【図８】縦フィン厚さに対する横フィン厚さの割合と、素子の温度上昇及び圧力損失との関係を示す図である。
【図９】横フィンピッチに対する縦フィン厚さの割合と、素子の温度上昇及び圧力損失との関係を示す図である。
【図１０】本発明のヒートシンクの各部構造を示す図で、（ａ）は平面図、（ｂ）は裏面図、（ｃ）は正面図、（ｄ）は側面図を示す。
【図１１】従来の沸騰冷却器の構造を説明する図で、（ａ）は外観斜視図、（ｂ）は冷却塔の内微を示部を示す図である。
【図１２】従来のヒートシンクの構造の一例を説明する断面図である。
【図１３】従来のヒートシンクの他の構造を説明する断面図である。
【図１４】従来のヒートシンクの別の構造を説明する断面図である。
【符号の説明】
１１，１１１，１２１，１３１・・・・・・ヒートシンク、１，１２・・・・・・基板、３，１３，１０３，１２３，１３３・・・・・・フィン、１４・・・・・・横フィン、４，１６，１０４・・・・・・素子、１００・・・・・・沸騰冷却型ヒートシンク、１０６・・・・・・冷却媒体[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a heat sink, and more particularly, to a heat sink for forcibly cooling a heat generating portion by a cooling fluid such as air flowing by a fan or the like.
[0002]
[Prior art]
Conventionally, in order to cool a large-capacity heating element, a method of cooling the element using a boiling cooler or a heat pipe has been generally used. FIG. 11 shows an external view of an example of the boiling cooler. The boiling cooler 100 has a pedestal 101 on which an element 104 that generates heat is mounted, a cooling tower 102 is connected to the pedestal 101, and a number of fins 103 are provided on an outer peripheral surface of the cooling tower 102. . The pedestal 101 and the cooling tower 102 are formed in an integrated container, and a cooling medium 106 such as fluorocarbon which is easily vaporized and has a large heat of vaporization is sealed therein. In this boiling cooler, the cooling medium 106 on the pedestal 101 below the cooling tower 102 is vaporized by the heat generated by the element 104 and rises to the upper part of the cooling tower 102. The cooling medium that has risen to the upper portion of the cooling tower 102 is condensed by the heat radiation of the fins 103, and falls again to the pedestal 101. By repeating the circulation of the cooling medium, the heat generated by the element is radiated, the element is prevented from being heated, and a constant temperature is maintained.
[0003]
However, in recent years, boiling coolers and heat pipes that use refrigerants are being abolished due to environmental problems related to global warming, and there is a remarkable tendency to switch to dry high-performance heat sinks that do not use refrigerants. For example, heat exchangers called heat sinks are provided at various heat generating parts of inverters, machine tools, etc., and a cooling fluid such as air is forced to flow through the heat sink by a fan or the like to cool the heat sink. Have been. The heat sink is made of a metal having good thermal conductivity, and is configured to increase the surface area as much as possible to increase the contact area with the cooling medium, thereby suppressing the temperature rise of various heating elements.
[0004]
Hereinafter, an example of this type of conventional heat sink will be described.
12 to 14 are front views illustrating the configuration of a conventional heat sink.
A conventional heat sink 111 shown in FIG. 12 includes a substrate 112 having a substantially rectangular planar shape to which electronic components (not shown) such as thyristors and transistors are fixed, and a large number of corrugated plate-shaped bends laminated on the substrate 112. And a fin 113 having a fin body 113a. This heat sink is not suitable for the purpose of dissipating a large amount of heat because the heat exchange efficiency of the plate bending fins is significantly reduced as the height is increased.
[0005]
A conventional heat sink 121 shown in FIG. 13 includes a substrate 122 having a substantially rectangular planar shape to which electronic components (not shown) such as thyristors and transistors are fixed, and lattice-like fins 123 made of an extruded material mounted on the substrate 122. It is configured. Since the lower limit of the thickness of the extruded material is usually about 0.6 mm, the heat sink has a large pressure loss at the fins and does not have a necessary cooling fluid such as air, so the cooling capacity is reduced. It has been difficult to increase the cooling efficiency of the steel.
[0006]
A conventional heat sink 131 shown in FIG. 14 includes a substrate 132 having a substantially rectangular planar shape to which electronic components (not shown) such as thyristors and transistors are fixed, and a large number of flat plate-shaped vertical members standing on the substrate 132. And a fin 133 having a fin body 133a. The vertical fin bodies 133a face each other in the direction of flow of a desired cooling fluid such as air (the direction perpendicular to the paper surface in the figure) with their side surfaces facing each other, and are maintained at an appropriate interval G to substantially keep the same. They are arranged in parallel.
[0007]
These heat sinks are used for small and low-capacity elements having a heat generation amount of 0.6 to 2 kW, and a wind speed applied to the fins is 2 to 3 m / s, and air cooling is performed using a sirocco fan or the like. Has been adopted.
[0008]
[Problems to be solved by the invention]
In recent years, the capacity of electronic elements has been increased, and a type in which one element generates 3 kW of heat has been put to practical use, and electronic devices using a plurality of such large-capacity elements have come to be employed. In order to improve the performance of the heat sink in response to the elements that generate a large amount of heat, the surface area of the fins must be increased, the spacing between the fins must be reduced, and the number of fins installed must be increased to increase the fins. A method of density arrangement is conceivable. Even with a structure in which the fins are arranged at high density, there is a limit to increasing the number of fins, and if the interval between the fins is reduced, the ventilation resistance (pressure loss) of cooling fluid such as air passing between the fins is reduced. ) Is increased, and as a result, the amount of air passing through the fin body is reduced, and there is a problem that the cooling efficiency cannot be improved.
[0009]
For example, heat sinks for control elements that generate a large amount of heat, such as control equipment for vehicles in recent years, cannot be infinitely increased in number of fins due to restrictions on mounting locations. It has been found that there is a limit in improving the performance, and the required cooling performance cannot be satisfied.
Therefore, a method of increasing the wind speed of the cooling air blown into the fins to 5 to 13 m / sec and cooling with a large amount of cooling air has been attempted. However, when the wind speed is increased, the pressure loss rapidly increases in the lattice-shaped fins, and a problem arises that the air volume does not increase as expected.
An object of the present invention is to suppress a rise in ventilation resistance (pressure loss) of a fin body as a heat sink for a large heat capacity element, secure a sufficient flow rate of cooling air, and as a result, enhance the heat radiation function of the entire heat sink, and provide cooling. An object is to provide a high-performance heat sink capable of improving efficiency.
[0010]
[Means for Solving the Problems]
As a result of repeated detailed experiments to solve the above-described problems, the heat sink of the present invention, in a heat sink having lattice-shaped fins, increases the thickness of the vertical fins to facilitate heat transfer from an element that generates heat. By increasing the height of the vertical fins to secure a heat dissipation area, and by increasing the opening area through which cooling air passes to suppress the rise in pressure loss, a large heat generation element It has enabled efficient cooling.
That is, the heat sink of the present invention is a heat sink comprising a substrate having a heating element bonded to the back surface, a plurality of vertical fins erected on the substrate, and a horizontal fin between the adjacent vertical fins. The thickness (T) of the vertical fin at the junction with the heat sink was 1.2 mm to 3.2 mm, and the height (H) of the vertical fin was 140 mm or more.
[0011]
In the heat sink according to the aspect of the invention, it is preferable that the thickness (t) of the horizontal fin be equal to or less than 0.38 times the thickness (T) of the vertical fin.
Preferably, the ratio of the thickness (T) of the vertical fins to the pitch (p) of the horizontal fins is 0.23 or less or 0.32 or more.
Further, it is preferable that the ratio of the pitch (p) of the horizontal fins to the pitch (P) of the vertical fins is 0.15 to 0.72.
When the heat sink is configured in such a dimensional relationship, it is possible to efficiently release the heat generated from the large-capacity element while suppressing the pressure loss while utilizing the large-capacity air flow.
[0012]
Further, in the heat sink according to the present invention, it is preferable that the thickness of the vertical fin is reduced as the distance from the junction with the substrate increases. The temperature decreases as the vertical fins move away from the joint, and the amount of heat transfer also decreases, so the heat capacity of the fins can be small, and it is better to reduce the thickness and increase the opening area of the grid-like part. This is advantageous because the loss can be reduced.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described in more detail with reference to the drawings.
1 to 3 show a heat sink of the present invention. FIG. 1 is an external perspective view of the heat sink, FIG. 2 is a sectional view taken along line AA ′ of FIG. 1, and FIG. 3 is a line B of FIG. FIG. 4 shows a cross-sectional view along the line −B ′.
In the following drawings, the scale is not always accurate for easy understanding of the structure.
As shown in FIGS. 1 to 3, a heat sink 11 of the present invention is mounted with a thyristor, an electronic component such as a transistor (omitted in FIG. 1), and the like. For example, a vertical dimension L and a horizontal dimension W are each about 600 mm. And a fin 13 having a number of vertical fins 13a and 13b erected on one surface (the upper surface in FIG. 1) of the substrate 12, and substantially between the adjacent vertical fins 13a and 13b. It is formed from horizontal fins 14 arranged horizontally.
The shape of the substrate 12 is not limited to a square flat plate, but may be a flat rectangular shape, a flat elliptical shape, a flat circular shape, or the like. As a material of the substrate 12, a metal having good thermal conductivity such as aluminum or copper is used. In particular, it is preferable to use aluminum or an aluminum alloy from the viewpoint of weight reduction.
As shown in FIG. 1, a number of vertical fins 13a and 13b are arranged on one upper surface of the substrate 12 so as to be substantially parallel to the flow direction F of the cooling fluid indicated by the arrow. The vertical fins 13a and 13b are also preferably made of a metal having good heat conductivity, for example, aluminum or an aluminum alloy.
[0014]
FIG. 2 is a cross-sectional view of the heat sink shown in FIG. 1 taken along the line AA ′, in which an element 16 is mounted on the back surface of the substrate 12, and a plurality of vertical fins 13 a and 13 b are substantially perpendicular to the surface of the substrate 12. It is erected in. A horizontal fin 14 is disposed between the vertical fins 13a and 13b, and the opening is configured to have a lattice-shaped cross section as a whole.
FIG. 3 is a cross-sectional view of the heat sink shown in FIG. 1 taken along the line BB ′. In FIG. 3, the horizontal fins 14 are arranged in parallel with each other substantially in the length direction of the vertical fins 13a and 13b. I have.
[0015]
FIG. 4 is a detailed cross-sectional view of the fin 13, in which a large number of horizontal fins 14 are arranged so as to connect between two parallel vertical fins 13a and 13b. By arranging a plurality of fins having such a cross-sectional shape, a lattice-like fin is formed as a whole. The fins 13 are manufactured by extrusion of aluminum or an aluminum alloy, and are brazed and fixed to the surface of the substrate 12 using a brazing sheet.
[0016]
FIG. 5 is an enlarged view of a part of the fin 13 shown in FIG. 4, and shows a part of the vertical fin 13b and three horizontal fins 14. Since the horizontal fins 14 are thin and weak in strength, as shown in FIG. 5, a part of the horizontal fins 14 is provided with a projection 14a serving as a support when the fins 13 are erected in parallel. Since the length of the projection 14a is slightly longer than the length of the other fins 14, when the fins 13 are erected in parallel, a slight gap occurs between each horizontal fin 14 and the adjacent vertical fins 13a, 13b. However, it hardly affects the pressure loss of the cooling air. FIG. 4 shows an example in which such protrusions 14a are provided at two places above and below the vertical fin 13b.
[0017]
As shown in FIGS. 4 and 5, in the heat sink of the present invention, the height of the vertical fins 13a and 13b is (H), the interval (pitch) between the vertical fins 13a and 13b is (P), and the thickness of the horizontal fin 14 is Is represented by (t), and the interval (pitch) between the horizontal fins 14 is represented by (p). A heat sink is designed by variously changing the values of T, t, P, and p, and a heat radiation experiment is repeated. As a result, the pressure loss of the air flowing between the lattice-shaped fins is small, and the heat generation of the element is effectively dissipated. The optimum values of T, t, P, and p for preventing the rise of the element temperature were determined. The experiment was performed by attaching a heating element having a total calorific value of 8 kW to the back surface of a substrate made of A1050 alloy of 600 × 600 × 28 mm. Cooling was performed by air cooling using a turbo fan, and cooling air having a wind speed of 9 m / sec was blown through a duct onto a heat sink having a lattice cross section. The target values of the heat sink characteristics are a pressure loss of 1200 Pa or less, a temperature rise of the element of 50 ° C. or less, preferably a pressure loss of 800 Pa or less and a temperature rise of the element of 40 ° C. or less.
[0018]
FIG. 6 is a diagram showing the relationship between the thickness (T) of the vertical fins 13a and 13b obtained as described above and the temperature rise and pressure loss of the element. Here, the thickness (T) of the vertical fins 13a and 13b indicates the thickness of the vertical fin near the joint between the vertical fin and the substrate. In FIG. 4, the portion is slightly thicker at the junction with the substrate, and is inclined so as to gradually become thinner as the distance from the substrate increases. However, since the temperature decreases as the distance from the substrate decreases, the amount of heat transfer decreases. This is because it is better to make the vertical fins thinner and secure the cross-sectional area of the opening as wide as possible, since the heat capacity of the fins can be reduced. Of course, the same thickness may be formed over the entire length of the vertical fin.
[0019]
From the curve b in FIG. 6, as the thickness (T) of the vertical fin increases, the cross-sectional area of the opening decreases, so that the pressure loss increases. On the other hand, the heat capacity of the vertical fin increases from the curve a in FIG. It can be seen that the rise in the element temperature can be suppressed to a low level because the number of elements increases. The pressure loss is 1200 Pa or less when the thickness (T) of the vertical fin is 3.2 mm or less, and when the temperature rise of the element is 50 ° C. or less, the thickness (T) of the vertical fin is 1.2 mm. That is all. Therefore, the appropriate thickness (T) of the vertical fin is set to be 1.2 mm or more and 3.2 mm or less. Preferably, the thickness (T) of the vertical fin is not less than 1.8 mm and not more than 3 mm. Within this range, the pressure loss can be 800 Pa or less, and the temperature rise of the element can be 40 ° C. or less.
[0020]
Next, FIG. 7 shows the relationship between the fin height (H) and the temperature rise and pressure loss of the element. The thickness (T) of the vertical fin at the joint with the substrate was 2 mm. It can be seen from the curve c in FIG. 7 that if the fin height (H) is 75 mm or more, the pressure loss becomes 1000 Pa or less, and from the curve d in FIG. 7 the temperature rise of the element becomes 40 ° C. or less. When the fin height (H) is 250 mm or more, the temperature rise of the element converges to 30 ° C. and hardly changes. This is because the fin temperature approaches the temperature of the cooling airflow, and the heat exchange efficiency is reduced. Therefore, it is not advantageous to lengthen the fin height (H) unnecessarily because the effect is small. If the fin height (H) is 140 mm or more, the pressure loss can be suppressed to 800 Pa or less even when the vertical fin thickness (T) is increased.
Therefore, the appropriate fin height (H) is set to 140 mm or more. In the heat sink of the present invention, the reduction in the cross-sectional area of the opening by increasing the thickness (T) of the vertical fin is compensated for by increasing the height (H) of the vertical fin, thereby reducing the cross-sectional area of the opening. As a result, the heat exchange area was increased, and at the same time, the flow rate of the cooling medium was increased to enable large-capacity heat radiation.
[0021]
Subsequently, the thickness (t) of the horizontal fin 14 was examined. Increasing the thickness (t) of the lateral fins 14 increases the heat capacity and facilitates heat transfer, but reduces the cross-sectional area of the opening, thereby increasing the pressure loss. Therefore, when the thickness (T) of the vertical fin is 2 mm and the height (H) of the vertical fin is 234.6 mm, the ratio of the horizontal fin thickness (t) to the vertical fin thickness (T) (100 × t) / T,%), and the results are shown in FIG. According to the curve f of FIG. 8, if t / T is 65% or less, the pressure loss becomes 1200 Pa or less, and if t / T is 38% or less, the pressure loss becomes 800 Pa or less. In each case, the temperature rise of the element is 30 ° C. or less. Therefore, the ratio of the horizontal fin thickness (t) to the vertical fin thickness (T) (100 × t / T) is preferably 65% or less, more preferably 38% or less.
[0022]
Finally, the ratio (100 × T / p,%) of the vertical fin thickness (T) to the horizontal fin pitch (p) was examined. This is because when the vertical fin thickness (T) is increased and the horizontal fin pitch (p) is reduced, the area of the opening decreases, and there is a concern that the pressure loss increases. Therefore, the measurement was performed when the vertical fin thickness (T) was 2 mm, the vertical fin height (T) was 234.6 mm, and the horizontal fin thickness (t) was 0.6 mm (t / T = 0.3). The results are shown in FIG. From the curve g in FIG. 9, the temperature rise of the element is 50 ° C. or less and the pressure loss is 1000 Pa or less in any case, but the ratio of the vertical fin thickness (T) to the horizontal fin pitch (p) (100 × T) / P) was between 0.23 and 0.32, it was found that the pressure loss exceeded 800 Pa. Therefore, the ratio (100 × T / p) of the vertical fin thickness (T) to the horizontal fin pitch (p) is preferably 23% or less or 32% or more.
[0023]
【Example】
A heat sink having each part structure shown in FIG. 10 and each fin size shown in Table 1 and Table 2 was prepared, and a heat dissipation experiment was performed to evaluate the performance. The fins 3 shown in FIG. 10 have the cross-sectional shape shown in FIG. 4 arranged side by side in the same direction. The substrate 1 is made of an A1050 aluminum alloy having a size of 550 × 550 × 28 mm, a double-sided brazing sheet 2 is inserted between the substrate 1 and the fins 3, and the substrate 1 and the fins 3 are brazed as shown in the figure. did. The fin 3 used A1070 aluminum alloy for both the vertical and horizontal fins. As shown in FIG. 10B, four heat-generating elements 4 having a high heat capacity of 2 kW were arranged and mounted on the windward side as a whole. Cooling was performed by air cooling using a turbo fan, and cooling air having a wind speed of 9 m / s was blown into a heat sink having a lattice cross section through a duct. The temperature rise of the device was measured by embedding a thermocouple near the bonding surface of the substrate 1 with the device 4. The pressure loss was measured by arranging a micro pressure gauge on the inlet side and the outlet side of the fin.
The measurement results are shown in Tables 1 and 2.
[0024]
[Table 1]

[0025]
[Table 2]

[0026]
(Comparative example)
For comparison, a heat sink having each part structure shown in FIG. 10 and each fin size shown in Table 3 was prepared, and a heat radiation experiment was performed in the same manner as in the example to evaluate the performance. Table 3 also shows the measurement results.
[0027]
[Table 3]

[0028]
According to the results of Tables 1 to 3, according to the present invention, in the heat sink to which the elements having a high calorific value are bonded, even if the wind speed is increased, the pressure loss in the lattice-shaped fins is suppressed to be low, and the efficient heat radiation of the elements is achieved. It can be seen that the performance of the element can be maximized.
[0029]
【The invention's effect】
According to the present invention, it is possible to suppress an increase in ventilation resistance (pressure loss) when the cooling fluid hits the fin body, and to bring in sufficient cooling fluid into the heat sink body to improve the cooling efficiency. The space to be installed is limited as in the case of the control device described above, and it is effective for controlling the temperature of a control element that generates a large amount of heat.
[Brief description of the drawings]
FIG. 1 is an external perspective view illustrating the structure of a heat sink according to the present invention.
FIG. 2 is a cross-sectional view of the heat sink of FIG. 1 taken along line AA ′.
FIG. 3 is a cross-sectional view of the heat sink of FIG. 1 taken along line BB ′.
FIG. 4 is a sectional view showing a structure of a vertical fin.
FIG. 5 is an enlarged view of a part of FIG. 4;
FIG. 6 is a diagram showing the relationship between the plate thickness of a vertical fin and the temperature rise and pressure loss of an element.
FIG. 7 is a diagram showing the relationship between the height of a fin and the temperature rise and pressure loss of an element.
FIG. 8 is a diagram showing the relationship between the ratio of the horizontal fin thickness to the vertical fin thickness and the temperature rise and pressure loss of the element.
FIG. 9 is a diagram showing the relationship between the ratio of the vertical fin thickness to the horizontal fin pitch and the temperature rise and pressure loss of the element.
10A and 10B are diagrams showing the structure of each part of the heat sink of the present invention, wherein FIG. 10A is a plan view, FIG. 10B is a rear view, FIG. 10C is a front view, and FIG. 10D is a side view.
11A and 11B are diagrams illustrating a structure of a conventional boiling cooler, in which FIG. 11A is an external perspective view, and FIG. 11B is a diagram illustrating a part of the inside of a cooling tower.
FIG. 12 is a cross-sectional view illustrating an example of the structure of a conventional heat sink.
FIG. 13 is a cross-sectional view illustrating another structure of a conventional heat sink.
FIG. 14 is a cross-sectional view illustrating another structure of a conventional heat sink.
[Explanation of symbols]
11, 111, 121, 131 ... heat sink, 1, 12 ... board, 3, 13, 103, 123, 133 ... fin, 14 ... Horizontal fin, 4, 16, 104: Element, 100: Boiling cooling heat sink, 106: Cooling medium

Claims (5)

A substrate having a heating element bonded to a back surface thereof, a plurality of vertical fins standing on the substrate, and a heat sink provided with horizontal fins between the adjacent vertical fins, wherein the vertical A heat sink characterized in that the thickness (T) of the fin is 1.2 mm to 3.2 mm and the height (H) of the vertical fin is 140 mm or more. The heat sink according to claim 1, wherein a thickness (t) of the horizontal fin is 0.38 times or less of a thickness (T) of the vertical fin. The heat sink according to claim 1 or 2, wherein a ratio of a thickness (T) of the vertical fin to a pitch (p) of the horizontal fin is 0.23 or less or 0.32 or more. The heat sink according to any one of claims 1 to 3, wherein a ratio of a pitch (p) of the horizontal fins to a pitch (P) of the vertical fins is 0.15 to 0.72. . The heat sink according to any one of claims 1 to 4, wherein a thickness of the vertical fin becomes thinner as the distance from the joint with the substrate increases.

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