JP2010219085A - Heat sink for natural air cooling - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heat sink capable of efficiently radiating heat from a heat-generating element even if it is a heat sink for natural air cooling which does not employ a blowing fan for forcible cooling. <P>SOLUTION: The heat sink for natural air cooling for cooling a heat-generating element in a casing has: a base plate having one surface thermally connected to the heat-generating element; and a heat radiating fin portion including a plurality of heat radiating fins whose lower ends are thermally connected to the other surface of the base plate. The fins each have one or more notches near to the upper end of a portion corresponding to the heat-generating element. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a natural air cooling heat sink that does not use a forced cooling fan or the like, and more particularly to a natural air cooling heat sink that causes natural convection and a natural air cooling cooling device using the same.

In recent years, ICs, CPUs, etc. have been used not only in special products such as personal computers but also in a wide range of fields such as home appliances. There is a need for a cooling device that can dissipate heat.
Conventionally, a heat sink has been used as one type of such a cooling device. In order to improve the performance of the heat sink, for example, as described in Patent Document 1, a heat radiating fin is joined to the other surface of the heat receiving plate to which the heating element is thermally connected to one surface. The electric fan is attached to the heat sink so that the cooling air passes between the heat dissipation fins, and the cooling air is forcibly sent between the heat dissipation fins by the rotation of the fan, and the heat transmitted from the heating element is dissipated into the atmosphere. Air-cooled heat sinks are used.

  In such a forced air cooling type heat sink, improvements such as a high-speed rotation of a fan or use of a large fan are being pursued in order to obtain a further excellent heat dissipation effect. For example, in the invention described in Patent Document 1, it is described that a cover is provided on a heat sink at a predetermined distance to increase the amount of air flowing between the fins and improve the cooling efficiency (FIG. 10). reference).

In addition, since heat sinks have been used in a wide range of home appliances and the like, there is a need for an efficient cooling device that is even lower in cost.
In order to reduce the cost of the heat sink, conventionally, a heat sink using an extruded aluminum material, which is inexpensive to manufacture, has been used. A heat sink made of an extruded material has been widely used because the heat receiving block and the heat radiating fin are integrally formed, and is easy to manufacture.

JP 2000-294695 A

  However, since the electric fan can forcibly send cooling air between the heat dissipation fins, the heat transmitted from the heat-generating parts to the heat sink can be effectively dissipated into the air and cooled, but the rotation of the fan In addition, there are problems such as the generation of noise and the high cost due to the installation of a fan.

  In addition, the heat sink made of extruded material is a heat sink having the same shape in cross section, and when trying to change the shape of the heat receiving block and the heat radiating fins according to various purposes, there is a problem of cost increase because grinding is required. .

  Such a heat sink made of an extruded material is designed with the maximum size according to the place where it is placed, such as the size of the housing, in order to enhance the heat dissipation performance. Therefore, since the heat sink is arranged so that the upper end of the fin is close to the inner wall of the housing, the air convection around the heat sink is limited between adjacent fins and the flow velocity is limited, effectively radiating heat. I couldn't.

  Accordingly, an object of the present invention is to provide a heat sink that can effectively dissipate heat from the heating element, even if it is a natural air cooling heat sink that does not use a forced cooling fan or the like.

  A first aspect of a natural air cooling heat sink according to the present invention is a natural air cooling heat sink for cooling a heat generating element in a housing, a base plate having one surface thermally connected to the heat generating element, and a lower end thereof. A heat radiating fin portion comprising a plurality of fins thermally connected to the other surface of the base plate, and the fin has one or more notches in the vicinity of the upper end portion of the portion corresponding to the heating element. It has the part.

  Another aspect of the natural air cooling heat sink according to the present invention is characterized in that the fin has a cut-and-raised portion corresponding to the shape of the notch on one side of the notch.

  In another aspect of the natural air cooling heat sink of the present invention, the notch has a rectangular shape with the upper side of the fin as one side, and the one side is one of the sides adjacent to the upper side. It is characterized by that.

  In another aspect of the natural air cooling heat sink of the present invention, the fin is a thin metal plate having a substantially L-shaped cross section including a heat receiving part thermally connected to the base plate and a heat radiating part rising from the heat receiving part. It is characterized by being.

  In another aspect of the natural air cooling heat sink of the present invention, the fin is formed near a top side of the fin, a heat receiving part thermally connected to the base plate, a first heat radiating part rising from the heat receiving part, It is a metal thin plate provided with the 2nd thermal radiation part thermally connected to a housing | casing, It is characterized by the above-mentioned.

  According to another aspect of the heat sink for natural air cooling of the present invention, the fin includes an elastic deformation portion that relaxes stress applied between the heat receiving portion and the second heat radiating portion in the first heat radiating portion. And

  According to the present invention, even if it is a natural air cooling heat sink that does not use a forced cooling fan or the like, heat convection in the housing can be promoted, so that heat from the heating element is effectively radiated. be able to.

1 is a perspective view of a natural air cooling heat sink 100 according to a first embodiment of the present invention. It is a side view which shows an example of the state which has arrange | positioned the natural air cooling heat sink 100 of this invention in the housing | casing. It is sectional drawing which shows an example of the state which has arrange | positioned the natural air cooling heat sink 100 of this invention in the housing | casing. It is a perspective view which shows another aspect of the fin used for this invention. It is a front view which shows an example of the metal plate material for manufacturing the fin used for this invention. It is a perspective view which shows the heat sink 200 for natural air cooling which concerns on the 2nd Embodiment of this invention. It is a side view which shows an example which has arrange | positioned the natural air cooling heat sink 200 which concerns on the 2nd Embodiment of this invention in the housing | casing. It is a perspective view which shows one aspect | mode of the fin 20B used for the natural air cooling heat sink which concerns on the 2nd Embodiment of this invention. It is a side view which shows another aspect of the fin 20B used for the heat sink for natural air cooling which concerns on the 2nd Embodiment of this invention. It is a perspective view which shows the heat sink which concerns on a prior art.

  A natural air cooling heat sink according to a preferred embodiment of the present invention will be described in detail with reference to the drawings. In addition, about each structural part which has the same function, the same code | symbol is attached | subjected and shown for simplification of illustration and description.

(First embodiment)
FIG. 1 is a perspective view of a natural air cooling heat sink according to the first embodiment of the present invention. As shown in FIG. 1, the natural air cooling heat sink 100 is thermally connected to a base plate 10 whose one surface is thermally connected to a heating element (cooled element) (not shown) and the other surface of the base plate 10. The plurality of fins 20 are provided with heat dissipating fin portions erected in parallel. In addition, the fin 20 includes a notch portion 25 in the vicinity of the upper end portion 23 of the portion corresponding to the portion to which the heat generating element of the base plate 10 is attached.

The base plate 10 is formed of a metal plate (for example, copper, aluminum, copper-tungsten alloy, etc.) having a thickness of about 0.2 to 3.0 mm and excellent in thermal conductivity. Moreover, the fin 20 is formed with the metal plate excellent in heat conductivity of thickness about 0.1-1.0 mm, for example. The base plate 10 and the fins 20 are thermally connected by various methods to be described later.
The vertical and horizontal lengths of the base plate 10 and the fins are appropriately designed according to the shape of the heating element to be arranged, the size of the housing, and the like.

  As the notch 25 formed in the fin 20, various shapes such as a triangle, a quadrangle, a polygon such as a trapezoid, an arc, and the like can be adopted. Is particularly preferred. Moreover, the notch 25 should just be formed in the fin arrange | positioned at least in the part to which a heat generating element is attached, However, It is desirable to be formed in all the fins.

  2 and 3 are a side view and a front view (a cross-sectional view taken along the line II ′ in FIG. 2) showing an example of a state in which the natural air cooling heat sink 100 of the present invention is disposed in the housing. As shown in FIG. 2, a substrate 32 on which various members are mounted and a heating element 34 mounted on the substrate 32 are arranged inside the housing 30. The heat sink 100 for natural air cooling according to the present invention is fixed to the substrate 32 by a fixing method (not shown) provided on the base plate 10 or the fin 20 with one surface of the base plate 10 thermally connected to the heating element 34. .

  The fin 20 includes a heat receiving portion 27 that is thermally connected to the base plate 10 and a heat radiating portion 29 that rises substantially vertically from the heat receiving portion 27, and has a substantially L-shaped cross section. A plurality of such fins 20 are erected on the base plate 10 to form a heat radiating portion.

  As shown in FIG. 3, the fin 20 includes a notch 25 in the vicinity of the upper end 23. A plurality of arrows A <b> 1 to A <b> 4 in FIGS. 2 and 3 indicate the flow of air around the natural air cooling heat sink 100.

  Here, the movement of heat in the heat sink will be described. First, the heat of the heating element 34 moves to the base plate 10 and diffuses throughout the surface of the base plate 10. Next, the heat that has moved to the base plate 10 moves to the heat receiving portion 27 of the fin 20 thermally connected to the base plate 10, and further moves to the heat radiating portion 29 so as to move above the natural air cooling heat sink 100. .

  Next, the flow of air around the natural air cooling heat sink 100 will be described. As shown in FIG. 2, the air heated in the vicinity of the base plate 10 of the natural air cooling heat sink 100 moves upward between the adjacent fins 20 (A1). At this time, the air is also warmed by the heat of the heat radiating portion 29 of the fin 20 while moving between the fins 20.

  Part of the air that has moved to the top of the natural air cooling heat sink 100 moves in a direction perpendicular to the heat radiating portion 29 of the fin 20 through the notch 25 provided in the vicinity of the upper end 23 of the fin 20. (A2). Further, as shown in FIG. 3, the other part of the air that has moved up to the top of the heat sink 100 moves in the surface direction of the heat radiating portion 29 of the fin 20 and escapes to the outside of the natural air cooling heat sink 100 (A3).

Along with the air flows A1 to A3, the air in the housing is introduced from the lower side of the natural air cooling heat sink 100 (A4). The air flows A1 to A4 circulate around the natural air cooling heat sink 100, whereby the heat of the heating element 34 can be efficiently dissipated to the air in the housing 30.
Here, since the natural air cooling heat sink 100 of the present invention includes the notch portion 25, the air moved to the upper portion of the heat sink 100 does not stay in the direction perpendicular to the heat radiating portion 29 of the fin 20. Since it moves, air circulation is further promoted, and efficient heat dissipation is possible.

  When there is no notch 25, most of the air (A4) introduced from the lower side of the heat sink 100 goes out from the upper side of the fin 20 (A3). For this reason, the flow velocity of the airflow (A1) at the center of the fin 20 (the portion corresponding to the heating element 34) is small, and the flow velocity of the airflow (A3) on the upper side of the fin 20 is large. In order to improve the heat dissipation efficiency, the notch 25 is installed at the center of the upper end 23 of the fin 20, and the airflow (A1) at the center of the fin 20 and the airflow (A2) passing through the upper end 23 of the fin 20 are generated. Facilitate.

  The cutout portion 25 may be provided at the upper end portion 23 of the fin 20 corresponding to the heating element 34. When installed on the side of the upper end portion 23 of the fin 20 (other than the portion corresponding to the heating element 34), the contact area between the air (A3) and the heat radiating portion 29, which originally has a high flow rate and a high heat transfer efficiency, is reduced. For this reason, the performance of the heat sink 100 as a whole may be deteriorated, which is not preferable.

  Next, the fin used for the natural air cooling heat sink of the present invention will be described in detail. FIG. 4 is a perspective view showing another embodiment of the fin used in the present invention. As illustrated in FIG. 4, the fin 20 </ b> A includes a cut-and-raised portion 25 a having a shape corresponding to the notch 25 in addition to the configuration of the fin 20 illustrated in FIG. 1.

  Although the manufacturing method of such a fin is not specifically limited, For example, as shown to Fig.5 (a), the metal plate 40A of the shape corresponding to the heat receiving part 27 and the thermal radiation part 29 is prepared. In the metal plate member 40A, a notch 41 corresponding to the notch 25 is formed at a predetermined position of the heat dissipating part 29. Thereafter, the heat receiving portion 27 and the cut and raised piece 25b are bent along the bent portion 42 so as to be substantially perpendicular to the heat radiating portion 29 by a press or the like, and used for the natural air cooling heat sink of the present invention. Fins can be formed.

  Here, as the shape of the cut and raised piece 25b, a quadrangular shape, a trapezoidal shape, a triangular shape, an arc shape, or the like as shown in FIGS. Here, the cut-and-raised part 25a is desirably formed along the air flows A1 to A3 described above.

  With such a configuration, the air around the heat sink can be circulated effectively without reducing the area of the heat radiating portion 29 of the fin 20A, so that heat can be radiated more efficiently.

(Second Embodiment)
FIG. 6 is a perspective view showing a natural air cooling heat sink 200 according to the second embodiment of the present invention. As shown in FIG. 6, in addition to the configuration of the fin 20A shown in FIG. 4, the fin 20B used in the natural air cooling heat sink 200 extends horizontally from the upper end portion 23 to the heat receiving portion 27, and is not shown in the figure. A second heat dissipating part 23a that is thermally connected to the body is provided. The second heat radiating portion 23a is connected to the second heat radiating portion 23a of another adjacent fin and forms a heat radiating surface.

FIG. 7 is a side view showing an example in which a natural air cooling heat sink 200 according to the second embodiment of the present invention is arranged in a housing. As shown in FIG. 7, the natural air cooling heat sink 200 has one surface of the base plate 10 thermally connected to the heating element 34 and is attached to the substrate 32 by a fixing method (not shown) provided on the base plate 10 or the fin 20B. In addition, the heat radiating surface formed by the second heat radiating portion 23 a is thermally connected to the housing via a TIM (Thermal Interface Material) 36.

  According to the second embodiment of the present invention, since the second heat radiating portion 23a formed on the upper end portion 23 of the natural air cooling heat sink 200 and the housing 30 are thermally connected, the heat generating element 34 is provided. This heat can be dissipated through the housing 30, so that the heat radiation efficiency can be further improved.

  As the TIM used in the second embodiment of the present invention, a heat transfer sheet, a heat conductive grease, or the like having a predetermined thickness can be used. In the case of using a heat transfer sheet, the thickness is preferably 0.2 mm or more and 1.0 mm or less in order to maintain good heat conductivity.

  FIG. 8 is a perspective view showing one aspect of the fin 20B used in the natural air cooling heat sink according to the second embodiment of the present invention. As shown in FIG. 8, the fin 20 </ b> B includes a heat receiving portion 27 that is thermally connected to a base plate (not shown) and a heat radiating portion (first heat radiating portion) 29 that rises substantially vertically from the heat receiving portion 27. Further, the fin 20 </ b> B includes a second heat radiating part 23 a extending horizontally from the upper end part 23 with respect to the heat receiving part 27.

The second heat radiating portion 23a may extend in the same direction as the heat receiving portion 27 with respect to the first heat radiating portion 29, or may extend in the opposite direction.
When the second heat radiating portion 23a extends in the same direction as the heat receiving portion 27 with respect to the first heat radiating portion 29, the cross section is substantially U-shaped.

  By installing a plurality of such fins 20B in parallel on the base plate, a heat sink thermally connected to the base plate and the housing can be formed as shown in FIG.

  FIG. 9: is a side view which shows another aspect of the fin used for the heat sink for natural air cooling which concerns on the 2nd Embodiment of this invention. As shown in FIG. 9, the fin 20C is provided with a convex portion (or a concave portion) 29a in the first heat radiating portion 29, and the stress applied between the heat receiving portion 27 and the second heat radiating portion 23a due to elastic deformation of this portion. I try to relax. The shape of the convex portion (or concave portion) 29a is not particularly limited as long as it has a predetermined elastic force, and various shapes such as a U-shaped cross section, a triangular shape, and a semicircular shape can be adopted. Moreover, the part which elastically deforms should just be provided in one or more places, and may be provided with two or more.

100, 200 Natural cooling heat sink 10 Base plate 20, 20A-C Fin 23 (fin) upper end portion 23a Second heat radiating portion 25 Notch portion 25a Cut and raised portion 25b Cut and raised piece 27 Heat receiving portion 29 Heat radiating portion (first 1 heat dissipation part)
29a Convex part (or concave part)
30 Housing 32 Substrate 34 Heating element 36 TIM
40A-D Metal plate material 41 Cut 42 Bending part

Claims (6)

A heat sink for natural air cooling for cooling a heating element in a housing,
A base plate having one surface thermally connected to the heating element;
The lower end portion includes a heat dissipating fin portion composed of a plurality of fins thermally connected to the other surface of the base plate,
The natural air cooling heat sink, wherein the fin has one or more notches in the vicinity of an upper end of a portion corresponding to the heating element.   2. The heat sink for natural air cooling according to claim 1, wherein the fin has a cut-and-raised portion corresponding to a shape of the notch portion on one side of the notch portion. The notch has a rectangular shape with the upper side of the fin as one side,
The natural air cooling heat sink according to claim 1, wherein the one side is one of sides adjacent to the upper side. The fin is a heat receiving portion thermally connected to the base plate;
The natural air cooling heat sink according to any one of claims 1 to 3, wherein the heat sink is a thin metal plate having a substantially L-shaped cross section including a heat radiating portion rising from the heat receiving portion. The fin is a heat receiving portion thermally connected to the base plate;
A first heat dissipating part rising from the heat receiving part;
4. The thin metal plate having a substantially U-shaped cross section provided with a second heat radiating portion formed in the vicinity of the upper side of the fin and thermally connected to the housing. The heat sink for natural air cooling according to any one of the items.   The natural air cooling heat sink according to claim 5, wherein the fin includes an elastic deformation portion that relieves stress applied between the heat receiving portion and the second heat radiating portion in the first heat radiating portion.

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