JPWO2013180270A1 - heatsink - Google Patents

Abstract

The heat sink (1) includes a vertical air flow path (6), and a plurality of lower cooling fins (5) and upper cooling fins (4) arranged radially so as to surround the vertical air flow path (6). A plurality of radial air flow paths are formed between adjacent lower cooling fins (5) or upper cooling fins (4), and the radial air flow paths are formed by lower cooling fins (5) and upper cooling fins (4). ) And the vertical air flow path (6). As a result, the heat dissipation efficiency of the heat sink (1) is improved.

Description

  The present invention relates to a heat sink that releases heat generated from an electronic device or the like constituting an electronic device or the like to cool the electronic device or the like.

  The heat sink is a device that releases heat generated from an electronic element or the like constituting an electronic device or the like to cool the electronic element, and includes a plurality of cooling fins (for example, Patent Document 1). In general, if the total surface area of the cooling fins is increased, the amount of heat radiation per unit time can be increased. However, since electronic devices and the like are required to be smaller and lighter, heat sinks are also required to be smaller and lighter. Yes. For this reason, the heat sink has a large number of cooling fins arranged at high density to increase the total surface area of the cooling fins.

  However, if a large number of cooling fins are arranged at a high density, the spacing between the cooling fins becomes small, and the flow rate of air flowing between the cooling fins becomes small. As a result, the heat dissipation performance is reduced. In such a case, a cooling fan is provided and cooling air is blown onto the cooling fins to perform forced cooling. However, if a cooling fan is provided, the volume and weight of the electronic device and the like will increase accordingly, which contradicts the demand for a reduction in size and weight.

  Therefore, there is a need for a heat sink that can achieve a desired cooling performance without using a cooling fan and that is small and light. For example, Patent Literature 2 discloses an air-cooled semiconductor heat sink including a plurality of heat radiation fins formed radially with respect to the axial direction of the heat pipe.

  In the air-cooled semiconductor heat sink disclosed in Patent Document 2, a plurality of radiating fins are arranged radially with respect to the axial direction of the heat pipe to form radiating fins parallel to the direction of gravity. For this reason, the air flow caused by buoyancy is not hindered, so that the heat dissipation performance is greatly improved.

JP 2002-368468 A JP 2003-100804 A1

  Certainly, in the air-cooled semiconductor heat sink disclosed in Patent Document 2, since the radiating fins are formed in parallel to the direction of gravity, the air flow caused by buoyancy is not hindered. However, the air received from the radiation fin near the lower end of the radiation fin flows along the radiation fin to form a boundary layer, and the temperature of the air forming the boundary layer rises toward the upper end of the radiation fin. Therefore, above the heat radiating fins, the heat radiating fins are enveloped in high-temperature air, so that no heat is radiated from the heat radiating fins to the air layer. Therefore, as shown in the drawing of Patent Document 2, even if the heat dissipating fins are extended in the height direction and the heat dissipating area of the heat dissipating fins is expanded, the increase in heat dissipating performance is small compared to the increase in the volume weight of the heat sink. Become. Therefore, there is a problem that the heat dissipation performance is low for the volume weight.

  The present invention has been made in view of the background as described above, and provides a heat sink having a high heat dissipation performance compared to the volume weight, that is, a heat sink having a desired heat dissipation performance and a small volume weight. Objective.

  In order to achieve the above object, a heat sink according to the present invention comprises a vertical air flow path and a plurality of cooling fins arranged radially so as to surround the periphery of the vertical air flow path. A plurality of radial air flow paths are formed between the fins, and the radial air flow paths are formed so as to communicate the outer circumferential space of the cooling fin and the vertical air flow path. .

  A heat receiving member that is connected to the object to be cooled in heat transfer and that is in contact with the lower surfaces of the plurality of cooling fins and mechanically couples the plurality of cooling fins may be provided.

  When the heat sink is viewed from above, the outer ends of the plurality of cooling fins may protrude further outward than the outer edge of the heat receiving member.

  A plurality of sets of the cooling fins are provided, and the sets of cooling fins are vertically stacked and offset around the central axis so that the upper cooling fins are positioned on the lower radial air flow path. It may be arranged.

  An interlayer annular member may be provided between the pair of adjacent cooling fins that are stacked one above the other and that mechanically couples the two and connects them thermally.

  According to the present invention, a plurality of radial air flow paths are formed between the cooling fins, and the radial air flow paths communicate with the outer peripheral space of the cooling fins and the vertical air flow paths. Since the air that has received heat radiation and has become high temperature flows into the vertical air flow path and rises and is discharged in the vertical air flow path, the low temperature air always hits the cooling fins. Therefore, the heat dissipation efficiency is increased.

  Moreover, if it has a heat receiving member that is connected to the object to be cooled in heat transfer and is in contact with the lower surfaces of the plurality of cooling fins and mechanically couples the plurality of cooling fins, the heat generated in the object to be cooled can be obtained. Since heat is equally transferred to the plurality of cooling fins, the heat dissipation efficiency is further increased. Further, when the heat sink is viewed in plan from above, if the outer end portions of the plurality of cooling fins protrude further outward than the outer edge of the heat receiving member, the heat sink flows into the cooling fin row from below the heat sink. Since the air streamline is improved, the heat dissipation efficiency is further increased.

  In addition, if a plurality of sets of cooling fins arranged radially so as to surround the vertical air flow path are provided, and the sets of cooling fins are stacked vertically, the number of cooling fins, Since the total heat radiation area increases, the heat radiation efficiency increases. In addition, if the cooling fins of the upper cooling fins are arranged on the radial air flow path of the lower cooling fins, the air whose temperature has increased by touching the lower cooling fins, Since the upper cooling fins are not touched, that is, the low-temperature air touches the upper cooling fins, the heat dissipation efficiency is further increased.

  Further, if an interlayer annular member is provided between the adjacent cooling fin sets and mechanically couples and heat-transfers the two, the lower cooling fin set is equivalent to the upper cooling fin set. The heat dissipation efficiency is further increased.

It is a notional top view of the heat sink concerning the present invention. It is a notional front view of a heat sink. It is sectional drawing which cut | disconnected the heat sink by the AA line of FIG. 1A. It is a notional top view of the upper module which constitutes a heat sink. It is a notional front view of an upper module. It is a notional top view of the lower module which constitutes a heat sink. It is a conceptual front view of a lower module. It is a conceptual front view which shows the flow of the cooling air around a heat sink. It is a conceptual sectional view showing a flow of cooling air around a heat sink. It is a figure which shows the definition of the dimension of a heat sink. It is a graph which shows the result of numerical simulation. It is a graph which shows the result of numerical simulation. It is a conceptual top view which shows the modification of a heat sink. It is a conceptual front view which shows the modification of a heat sink. It is a conceptual top view which shows the modification of a heat sink. It is a perspective view of a heat sink. It is a top view of a heat sink. It is an elevation view of a heat sink. It is an elevation view of a heat sink. It is an elevation view of a heat sink. It is an elevation view of a heat sink. It is a graph which shows the relationship between the weight of a heat sink, and thermal resistance.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.

  A conceptual configuration of a heat sink 1 according to the present invention is shown in FIGS. 1A to 1C. 1A is a plan view of the heat sink 1, FIG. 1B is a front view, and FIG. 1C is a cross-sectional view of the heat sink 1 taken along the line AA of FIG. 1A.

  As is apparent from FIGS. 1A to 1C, the heat sink 1 includes an upper fin row 2 and a lower fin row 3. The upper fin row 2 has 18 upper cooling fins 4 arranged radially (specifically, extending in a radial direction around the central axis X and arranged in an annular shape as a whole). And disposed above the lower fin row 3. The lower fin row 3 has 18 lower cooling fins 5 arranged radially (specifically, extending radially in the center axis X and arranged in an annular shape as a whole). doing. Each of the upper cooling fin 4 and the lower cooling fin 5 is a metal (for example, aluminum alloy or brass) flat plate that is rectangular in a planar shape.

  Further, the upper cooling fins 4 and the lower cooling fins 5 are arranged at equal pitches on the circumference centered on the central axis X so as to have a pitch of 20 ° at the central angle. The upper fin row 2 and the lower fin row 3 are offset by 10 ° at the central angle. That is, in the plan view (FIG. 1A), the lower cooling fins 5 are arranged so as to be visible between two adjacent upper cooling fins 4.

  The upper fin row 2 and the lower fin row 3 are arranged in a so-called donut shape in a plan view (FIG. 1A), and a vertical air flow path 6 is formed at the center of the upper fin row 2 and the lower fin row 3. ing. The vertical air flow path 6 is a cylindrical cavity centering on the central axis X, and penetrates from the lower surface to the upper surface of the heat sink 1. In other words, the upper cooling fins 4 and the lower cooling fins 5 are arranged radially around the vertical air flow path 6.

  In addition, a first cylindrical member 7 and a second cylindrical member 8 are disposed between the upper fin row 2 and the lower fin row 3. Each of the first cylindrical member 7 and the second cylindrical member 8 is a cylindrical metal member centered on the central axis X, and mechanically couples the upper fin row 2 and the lower fin row 3. At the same time, it functions as an interlayer annular member that couples the two in a heat transfer manner.

  An annular member 9 is disposed below the lower fin row 3. The annular member 9 is a metal member that is mechanically coupled to the lower fin row 3 and is a member that is thermally connected to the cooling target of the heat sink 1. That is, the annular member 9 functions as a heat receiving member that receives the exhaust heat of the cooling target. In the present embodiment, the planar heat pipe 10 is in heat transfer contact with the lower surface of the annular member 9, and a heating element 11 (an object to be cooled) such as an LED is attached to the lower surface center of the planar heat pipe 10. It is done. Therefore, the heat generated in the heating element 11 is transferred to the annular member 9 through the planar heat pipe 10, and from the annular member 9 to the lower fin row 3, the first cylindrical member 7 and the second cylindrical member 8. Then, heat is transferred to the upper fin row 2, and is transferred from the lower fin row 3 and the upper fin row 2 to the environment, that is, ambient air.

  The heat sink 1 is configured by combining an upper module 12 as shown in FIGS. 2A and 2B and a lower module 13 as shown in FIGS. 2C and 2D.

  The upper module 12 is formed by forging a metal material. As shown in FIGS. 2A and 2B, the upper module 12 includes 18 upper cooling fins 4, that is, the upper fin row 2 and the first and second cylindrical members 7 and 8. Prepare. In the upper module 12, the upper cooling fins 4 are mechanically coupled to the first and second cylindrical members 7 and 8 in a lattice shape. A radial air flow path 14 is formed between adjacent upper cooling fins 4. Accordingly, 18 radial air passages 14 are formed in the upper fin row 2, and communicate with the outside of the vertical air passage 6 and the lower fin row 3.

  The lower module 13 is also formed by forging a metal material, and includes 18 lower cooling fins 5, that is, the lower fin row 3 and the annular member 9, as shown in FIGS. 2C and 2D. In the lower module 13, the lower end of the lower cooling fin 5 abuts on the annular member 9 and is mechanically coupled. A radial air flow path 15 is also formed between adjacent lower cooling fins 5. Accordingly, 18 radial air passages 15 are formed in the lower fin row 3 and communicate with the vertical air passage 6 and the outside of the lower fin row 3.

  With this configuration, the heat sink 1 excites the flow of cooling air as shown in FIGS. 3A and 3B. 3A and 3B, a curve with an arrow indicates a streamline of cooling air flowing into and out of the heat sink 1.

  That is, since the upper fin row 2 and the lower fin row 3 are offset by 10 ° at the central angle, as shown in FIG. 3A, the upper fin row 2 and the lower fin row 3 flow from below the heat sink 1 and follow the surface of the lower cooling fin 5. The cooling air that flows and receives the heat from the lower cooling fins 5 and rises in temperature passes through between the upper cooling fins 4 and escapes above the heat sink 1. Further, the cooling air that has flowed away from the lower cooling fins 5, that is, between the two adjacent lower cooling fins 5, receives almost no heat from the lower cooling fins 5 and remains in the upper fin row 2 at a low temperature. It flows in along the surface of the upper cooling fin 4, receives heat from the upper cooling fin 4, and exits above the heat sink 1. That is, since the low-temperature cooling air flows into both the upper fin row 2 and the lower fin row 3, heat is efficiently radiated (cooled).

  Further, as shown in FIG. 3B, a part of the cooling air flowing from the lower side of the heat sink 1 passes through the lower fin row 3 and the upper fin row 2 and passes above the heat sink 1 as described above, and the remainder is It flows into the vertical air flow path 6, passes through the vertical air flow path 6, and exits above the heat sink 1. Further, a part of the cooling air flowing into the radial air flow path 15 (see FIG. 2C) between the two adjacent lower cooling fins 5 from the side of the lower fin row 3 passes through the upper fin row 2, It escapes above the heat sink 1, and the remainder flows into the vertical air flow path 6 and passes through the vertical air flow path 6 and above the heat sink 1. A part of the cooling air flowing into the radial air flow path 14 (see FIG. 2A) between the two adjacent upper cooling fins 4 from the side of the upper fin row 2 passes above the heat sink 1, and the remainder is vertical. It flows into the air flow path 6, passes through the vertical air flow path 6, and exits above the heat sink 1. As described above, the heat sink 1 has a portion where the cooling air stagnates, that is, a dead end, and does not have a shape like a narrow path, and therefore can efficiently radiate (cool) heat.

  Now, in order to confirm the performance of the heat sink 1, a numerical simulation for estimating the total thermal resistance was performed assuming the following 13 types of models (model Nos. 1 to 13). For comparison, a numerical simulation was also performed on a heat sink model (conventional product) according to the related art disclosed in Patent Document 2.

No. 1: Initial model no. 2: A model in which the fins are enlarged in the radial direction and the height direction, the inner diameter is reduced, and the outer diameter is substantially the same as the initial model.
No. 3: A model in which the fin is enlarged in the radial direction and the height direction, the inner diameter is the same as the initial model, and the outer diameter is increased.
No. 4: A model in which the fins are enlarged in the radial direction without changing the height of the fins, and the inner diameter is the same as the initial model.
No. 5: A model in which the fins are raised and the inner and outer diameters are the same as the initial model.
No. 6: No. A model based on 4 models with the lower fin raised 50mm.
No. 7: No. A model based on 4 models with increased ring thickness.
No. 8: No. This model is based on 4 models, and the height of the lower and upper fins is increased by 25 mm each.
No. 9: No. Deformed model based on 8 models.
No. 10: No. Based on 9 models, the number of fins is changed from 24 to 18.
No. 11: No. A deformation model based on 10 models.
No. 12: No. A deformation model based on 11 models.
No. 13: No. A deformation model based on 11 models.
Conventional product: a heat sink disclosed in Patent Document 2, Model having almost the same fin area as 2-5 model.

  Model No. Table 1 shows dimensions of 1 to 13 and conventional products. Refer to FIG. 4 for the meanings of dimensions and the like shown in Table 1.

  As is clear from Table 1, model no. The dimensions (outer diameter and height) of 1 to 13 are all smaller than the conventional product. Model No. Except for 6 and 8, the heat dissipation part weight of each model is smaller than the conventional product.

  Table 2 shows the results of the numerical simulation. 5 and 6 are graphs in which the total area of the cooling fins and the heat radiation part weight of the heat sink are plotted on the horizontal axis, and the result of the numerical simulation (total thermal resistance) is plotted on the vertical axis.

  As is clear from Table 2, model no. The thermal resistance of 1 to 13 is 70% or less of the conventional product. That is, the heat resistance of the heat sink according to the present invention is smaller than that of the conventional heat sink, and is excellent in heat dissipation. Further, as apparent from FIG. 5, the total thermal resistance tends to decrease when the fin area is increased, but the thermal resistance is about half that of the conventional type even when the area of the cooling fin is equal to that of the conventional type. It is. Model No. The fin areas of 2 to 5 are almost the same, but the total thermal resistance is model no. 4 is the smallest. From this, it can be seen that if the fin area is substantially the same, the total thermal resistance decreases as the fin outer diameter increases. In other words, increasing the fin radius to increase the cooling fin area is more effective in reducing the total thermal resistance than increasing the fin height to increase the cooling fin area. I understand. Even if the height of the fin is increased, a boundary layer flow in which the cooling air rises along the surface of the fin develops, and the average temperature of the cooling air in contact with the fin increases. Moreover, even if the plate thickness of the fin is increased, the effect of reducing the total thermal resistance is low. The decrease in internal thermal resistance is considered not to have a significant effect on the decrease in total thermal resistance. Therefore, it is desirable to increase the fin area while leaving the plate thickness as it is, or to reduce the plate thickness and to increase the floating weight to increase the fin area.

  Further, since the weight of the heat sink is substantially proportional to the area of the cooling fin, as shown in FIG. 6, when the weight increases, the thermal resistance decreases, but the weight is comparable to the conventional product, and the thermal resistance is About half of the mold.

  Further, the thermal resistance of the heat sink 1 decreases when the fin row is arranged so as to overhang the annular member 9. In other words, when the heat sink 1 is viewed from above, the outer sides of the plurality of cooling fins constituting the fin row, that is, the outer ends of the vertical air flow paths 6 are further outside the outer edge of the annular member 9. In other words, if it is arranged so as to protrude in a direction away from the vertical air flow path 6, the performance of the heat sink 1 is improved.

  In order to verify the effect of overhang, three types of cooling fin arrays with different fin areas were set, and four types of models with different overhang amounts for each type (Examples 1 and 2, Comparative Examples 1 and 2). That is, a total of 12 types of models were set, and the thermal resistance of each model was calculated.

The following three types of cooling fin arrays were used for the calculation.
Type 1: 18 cooling fins having a width of 40 mm and a height of 60 mm.
Type 2: It has 18 cooling fins with a width of 50 mm and a height of 60 mm.
Type 3: It has 18 cooling fins with a width of 55 mm and a height of 60 mm.
The material of the cooling fins is copper, and the plate thickness is 3 mm.

  For the three types of cooling fin arrays, two types of models in which the cooling fin array overhangs, that is, Examples 1 and 2, and two models in which no overhanging occurs, that is, Comparative Examples 1 and 2 were set.

[Example 1]
FIG. 9 is a perspective view illustrating an outer shape of the heat sink 21 according to the first embodiment. As shown in FIG. 9, the heat sink 21 includes a cooling fin row 23 composed of 18 cooling fins 22 arranged radially, and an annular member 24 that is in heat transfer contact with the lower surface of the cooling fin row 23. The cooling fin row 23 (cooling fin 22) is fixed to the annular member 24. The material of the annular member 24 is aluminum, and the plate thickness is 8 mm.

  As shown in FIG. 10, the cooling fin row 23 and the annular member 24 are arranged concentrically, and the cooling fin row 23 overhangs the annular member 24. That is, the outer diameter Do of the cooling fin row 23 is made larger than the outer diameter Dbo of the annular member 24. In other words, when the heat sink 21 is viewed from above, the outer end portion of the cooling fin 22 is outside the outer edge of the annular member 24 (the side away from the center of the cooling fin row 23 and the annular member 24). Di is the inner diameter of the cooling fin row 23 and corresponds to the diameter of the vertical air flow path 6 (see FIG. 1C). A central hole 25 is formed at the center of the annular member 24, and Dbi is the diameter (inner diameter) of the central hole 25.

  As shown in FIG. 11, the heat sink 21 is used by being attached to a heating element 26 such as an LED substrate. The heating element 26 is attached to the lower surface of the annular member 24 by heat transfer, and the center hole 25 is closed by the heating element 26. In addition, H is a code | symbol which shows the height of the cooling fin row | line | column 23 (cooling fin 22).

[Example 2]
FIG. 12 is an elevation view of the heat sink 27 according to the second embodiment. The basic configuration and material of the heat sink 27 are the same as those of the heat sink 21, but differ in that the overhang of the cooling fin row 23 with respect to the annular member 24 is smaller than that of the heat sink 21. That is, the difference between the outer diameter Do of the cooling fin row 23 and the outer diameter Dbo of the annular member 24 is smaller than that of the heat sink 21.

[Comparative Example 1]
FIG. 13 is an elevation view of the heat sink 28 according to Comparative Example 1. FIG. The basic configuration and material of the heat sink 28 are the same as those of the heat sink 21, except that the cooling fin row 23 does not overhang with respect to the annular member 24. The outer diameter Do of the cooling fin row 23 is equal to the outer diameter Dbo of the annular member 24.

[Comparative Example 2]
FIG. 14 is an elevation view of the heat sink 29 according to Comparative Example 2. The basic configuration and material of the heat sink 29 are the same as those of the heat sink 21, except that the outer diameter Dbo of the annular member 24 is larger than the outer diameter Do of the cooling fin row 23.

[Each model of type 1]
The main dimensions of each type 1 model are as follows.

[Each model of type 2]
The main dimensions of each type 2 model are as follows.

[Each model of type 3]
The main dimensions of each type 3 model are as follows.

  When the above three types and 12 models were numerically simulated, the following results were obtained. In the numerical simulation, it was assumed that the ambient temperature was 298.15 ° K (25 ° C) and the heat generation amount of the heating element 26 was 70W. The “heating element temperature” in the following table is the temperature at the center of the lower surface of the heating element 26 when the heating value of the heating element 26 and the heat dissipation amount by the heat sinks 21 and 27 to 29 are balanced.

  FIG. 15 shows the relationship between the weight and thermal resistance of the 12 models. FIG. 15 shows that the thermal resistance decreases in the order of types 1, 2, and 3. That is, it can be seen that the thermal resistance decreases as the surface area of the cooling fin row increases. Moreover, it turns out that the thermal resistance of Example 1 is the smallest among the models of the same type. That is, it can be seen that when the cooling fin row 23 is overhanged with respect to the annular member 24, the thermal resistance is lowered. This is because the air below the heat sink 21 flows into the cooling fin row 23 through the overhang portion and cools the cooling fin row 23 efficiently. In addition, refer to FIG. 3B for the streamline of the air flowing into the cooling fin row 23 through the overhang portion.

  Further, according to FIG. 15, it is understood that when the cooling fin row 23 is overhanged with respect to the annular member 24, the weight of the heat sink 21 is reduced. That is, it can be seen that if the cooling fin row 23 is overhanged with respect to the annular member 24, not only the heat resistance of the heat sink 21 can be reduced, but also the weight of the heat sink 21 can be reduced.

  Although specific embodiments of the present invention have been described above, the technical scope of the present invention is not limited thereto. As long as the technical idea described in the scope of claims is applied, the invention can be freely modified and improved.

  For example, the heat sink 1 is not limited to one in which two rows of cooling fins are stacked. As shown in FIG. 7, the heat sink 1 may be configured with only one cooling fin row. Further, the shape of the heat sink 1 is not limited to the one configured as a column as a whole as shown in FIGS. 1 to 3. Various modifications are possible. Further, as shown in FIG. 8, the heat sink 1 may be formed in a prismatic shape as a whole so that the planar shape of the heat sink 1 is inscribed in a rectangular shape. Further, the planar shape (cross-sectional shape) of the vertical air flow path 6 is not limited to a circle.

  In the description of the above embodiment, the annular member 9 or the annular member 24 is shown as a specific example of the heat receiving member, but the heat receiving member is not limited to one having an annular planar shape. That is, the heat receiving member is not limited to one having an opening at the center. It may be a flat plate (for example, a circular plate) having no opening. Alternatively, the opening may be closed with another member.

  It goes without saying that the material of the heat sink 1 and the like can be arbitrarily selected according to the application and use environment.

  In addition, the present invention relates to the “demonstration of low energy consumption type light and fishery by low energy consumption type high brightness and small LED underwater lighting” related to the 2011 new industrial technology development project of the New Energy and Industrial Technology Development Organization. It is a product of “research”.

  The present application claims priority based on Japanese Patent Application No. 2012-125170 filed on May 31, 2012, including the specification, claims, figures, and abstract. The disclosure of this original patent application is hereby incorporated by reference in its entirety.

  INDUSTRIAL APPLICABILITY The present invention is useful as a heat sink that is attached to an electronic device or the like and releases heat generated from the electronic element or the like to the environment to cool the electronic element.

1 heat sink 2 upper fin row 3 lower fin row 4 upper cooling fin 5 lower cooling fin 6 vertical air flow path 7 first cylindrical member 8 second cylindrical member 9 annular member 10 planar heat pipe 11 heating element 12 upper module 13 Lower module 14 Radial air flow path 15 Radial air flow path 21 Heat sink 22 Cooling fin 23 Cooling fin row 24 Annular member 25 Center hole 26 Heating element 27 Heat sink 28 Heat sink 29 Heat sink

[0002]
Prior Art Literature Patent Literature [0006]
Patent Document 1: Japanese Patent Laid-Open No. 2002-368468 Patent Document 2: Japanese Patent Laid-Open No. 2003-100484 Summary of the Invention Problems to be Solved by the Invention [0007]
Certainly, in the air-cooled semiconductor heat sink disclosed in Patent Document 2, since the radiating fins are formed in parallel to the direction of gravity, the air flow caused by buoyancy is not hindered. However, the air received from the radiation fin near the lower end of the radiation fin flows along the radiation fin to form a boundary layer, and the temperature of the air forming the boundary layer rises toward the upper end of the radiation fin. Therefore, above the heat radiating fins, the heat radiating fins are enveloped in high-temperature air, so that no heat is radiated from the heat radiating fins to the air layer. Therefore, as shown in the drawing of Patent Document 2, even if the heat dissipating fins are extended in the height direction and the heat dissipating area of the heat dissipating fins is expanded, the increase in heat dissipating performance is small compared to the increase in the volume weight of the heat sink. Become. Therefore, there is a problem that the heat dissipation performance is low for the volume weight.
[0008]
The present invention has been made in view of the background as described above, and provides a heat sink having a high heat dissipation performance compared to the volume weight, that is, a heat sink having a desired heat dissipation performance and a small volume weight. Objective.
Means for Solving the Problem [0009]
In order to achieve the above object, a heat sink according to the present invention comprises a central vertical air flow path and a plurality of cooling fins radially extending around the central vertical air flow path, and the adjacent cooling fins. Between the cooling fins, an end vertical air flow path penetrating the cooling fins in the vertical direction is formed at an end portion of the cooling fin away from the central vertical air flow path. A plurality of radial air flow paths are formed between the fins, and the radial air flow paths are formed so as to connect the outer circumferential space of the cooling fin and the central vertical air flow path. And
[0010]
The lower surface of the plurality of cooling fins is connected to an object to be cooled in heat transfer

Claims (5)

In the heat sink,
A vertical air flow path;
A plurality of cooling fins arranged radially to surround the periphery of the vertical air flow path;
A plurality of radial air flow paths are formed between the adjacent cooling fins,
The said radial air flow path is formed so that the space of the outer periphery of the said cooling fin and the said vertical air flow path may be connected. The heat sink characterized by the above-mentioned. The heat receiving member that is coupled to the object to be cooled in heat transfer and mechanically couples the plurality of cooling fins in contact with the lower surfaces of the plurality of cooling fins. heatsink. 3. The heat sink according to claim 2, wherein, when the heat sink is viewed in plan from above, outer ends of the plurality of cooling fins protrude further outward than an outer edge of the heat receiving member. A plurality of sets of the cooling fins are provided,
The sets of cooling fins are stacked one above the other and are arranged offset around the central axis so that the upper cooling fins are positioned on the lower radial air flow path. The heat sink according to any one of claims 1 to 3. 5. The heat sink according to claim 4, further comprising an interlayer annular member that is disposed between adjacent sets of cooling fins that are stacked one above the other and that mechanically couples the two and thermally connects the two.

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