JP2003017878A - Heat sink - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat sink where a difference in temperature in a radiation surface of a radiation fin is reduced in a direction which is at right angles with respect to the arrangement direction of the radiation fins. SOLUTION: The heat sink comprises a base section 2 which can transmit and receive heat with a heating body, and a plurality of radiation fins 3 provided in the base section 2, with each radiation fin 3 being formed with radiation surfaces 5 on both sides in the arrangement direction of the radiation fins. The thickness of each radiation fin 3 is the arrangement direction of the radiation fins 3 is such, that the thickness T2 of a region, corresponding substantially to a center W2 of the heating body in the direction at right angles with the arrangement direction of the radiation fins 3, is larger than a thickness T3 of a region corresponding to parts other than those substantially at the center W2 of the heating body.

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat sink configured to radiate heat of a heating element from a radiation fin. [0002] Conventionally, it is known to use a heat sink to dissipate heat of a heating element into the air and to suppress a rise in the temperature of the heating element. The heat sink includes a plate-shaped base portion and a plurality of radiating fins integrally formed on the surface of the base portion and arranged at predetermined intervals. This heat sink is made of a metal material having excellent heat conductivity, for example, aluminum, an aluminum alloy, or the like. The heat sink is arranged so that the base and the heating element can exchange heat. Then, when the heat of the heating element is transmitted to the base portion, the heat is transmitted to the radiating fins, and heat exchange is performed based on the temperature difference at the surface of the radiating fins, that is, at the boundary surface between the radiating surface and the air. It is carried out. By such a heat transfer function, a rise in the temperature of the heating element is suppressed. It is desired to improve the heat radiation performance of the heat sink as described above without increasing the size of the heat sink. Therefore, the thickness of each heat radiation fin is set as thin as possible. In addition, a configuration is adopted in which the gap between the radiation fins is set as narrow as possible. By adopting this configuration, the total number of radiating fins within a predetermined area of the base increases, so that the radiating area of the entire heat sink is increased, and the heat transfer coefficient of the entire heat sink is improved. As described above, when adopting a configuration in which the radiation fins are made thinner and the radiation area is enlarged, the planar shape (cross-sectional shape) of the radiation fins in the arrangement direction of the radiation fins is as shown in FIG. It becomes almost rectangular. More specifically, each radiating fin 101 of the heat sink 100
Is set such that a thickness T1 in the arrangement direction is shorter than a length L1 in a direction orthogonal to the arrangement direction. In the length direction of the heat radiation fins, the heat radiation surfaces 103 forming the long sides of the heat radiation fins 101 are formed in a straight line over the entire length, and the heat radiation surfaces 103 are mutually parallel. That is, the thickness T1 is constant in the length direction of the radiation fin 3. As described above, in the heat radiation fin 101 having a substantially rectangular cross-sectional shape, when the heat of the heat generation center W1 is conducted around the heat radiation center 101 and reaches the heat radiation surface 103, the heat is transmitted from the heat radiation surface 103 to the air. You. Here, the heat conduction action in a plane in the arrangement direction of the radiation fins 101 will be described. The isotherm 104 indicating the temperature distribution inside the radiation fin 101 has a substantially elliptical shape centered on the heat generation center W1. Specifically, a single axis (not shown) of the elliptical isotherm 104 is located in the thickness direction of the radiation fin 101. When the isotherm 104 and the heat radiating surface 103 come into contact with the displacement of the elliptical isotherm 104, the temperature is based on the temperature difference between the air and the heat radiating surface in the region B1 where the isotherm 104 and the heat radiating surface 103 are in contact. Heat transfer takes place. [0006] However, as described above, the radiation fin 10 having a substantially rectangular cross-sectional shape as described above.
In the case of 1, at a certain point in the heat conduction process inside the radiation fin 101, that is, the process in which the isotherm 104 shifts to the outside, the radiation surface 103 is linear and the isotherm 104 is elliptical. Therefore, a plurality of isotherms 104 appearing on the heat radiation surface 103 exist. That is, on one heat radiation surface 103, the temperature is low at the end in the length direction orthogonal to the arrangement direction of the heat radiation fins 101, and the temperature is high at the center in the same length direction. There is still room for improvement from the viewpoint of improving. The present invention has been made in view of the above circumstances, and at a certain point in the heat conduction process of the radiation fin,
An object of the present invention is to provide a heat sink having good heat radiation efficiency by reducing the temperature difference on the surface of the heat radiation fin in a direction orthogonal to the arrangement direction of the heat radiation fins. [0008] In order to achieve the above object, the present invention provides a base capable of exchanging heat with a heating element and a plurality of heat radiators provided on the base. In the heat sink having fins and heat radiation surfaces formed on both sides in the arrangement direction of each heat radiation fin, the thickness of each heat radiation fin in the arrangement direction of the heat radiation fins is:
The thickness of a region corresponding to substantially the center of the heating element in a direction orthogonal to the arrangement direction of the radiation fins is set to be thicker than the thickness of a region corresponding to a region other than substantially the center of the heating element. It is characterized by having. In a plane in the arrangement direction of the radiating fins, an operation when heat conduction is performed from a region substantially corresponding to the center of the heating element inside the radiating fins is schematically described. Proceeds to expand. In the present invention, the thickness of the region corresponding to substantially the center of the heating element in the direction orthogonal to the arrangement direction of the radiation fins is thicker than the thickness of the region corresponding to a portion other than substantially the center of the heating element. At a certain point in the heat conduction process inside the radiation fin,
The number of contact points between one isotherm and the heat dissipation surface is reduced,
The temperature difference on the surface of the radiation fin in the direction orthogonal to the arrangement direction of the radiation fin is reduced. Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 2 is a perspective view showing the heat sink 1. The heat sink 1 is made of a metal material having excellent thermal conductivity, such as aluminum or an aluminum alloy. The heat sink 1 has a plate-shaped base portion 2 and a plurality of radiating fins 3 integrally formed on a single surface 4 side of the base portion 2. Each of the heat radiation fins 3 extends in the thickness direction of the base portion 2, and the heat radiation fins 3 are arranged at predetermined intervals. FIG. 1 is a schematic plan view showing the structure of the heat sink 1. As shown in FIG.
Has a predetermined length L2. The length of the radiating fins 3 means a dimension in a direction parallel to the surface 4 of the base portion 2 and perpendicular to the arrangement direction of the radiating fins 3. Further, the thickness of each heat radiation fin 3 differs depending on the position in the length direction of the heat radiation fin 3. The thickness of the heat radiation fins 3 is a direction parallel to the surface 4 of the base portion 2 and means a dimension in the arrangement direction of each heat radiation fin 3. In the embodiment shown in FIG. 1, the thickness of the heat radiation fin 3 is set substantially at the center in the longitudinal direction of the heat radiation fin 3,
The thickness T3 is set at both ends in the length direction. Here, the thickness T2 is thicker than the thickness T3, and the length L2
Is longer than the thicknesses T2 and T3. The thickness T2 is the maximum thickness of the radiation fin 3 and the thickness T3 is the minimum thickness of the radiation fin 3. Further, heat radiating surfaces 5 are formed on both sides in the thickness direction of each heat radiating fin 3. The heat radiation surface 5
In the longitudinal direction of the heat radiation fins 3, the heat radiation fins 3 are divided into a first heat radiation surface 6 and a second heat radiation surface 7. In a plane in the arrangement direction of the heat radiation fins 3, the first heat radiation surface 6 and the second heat radiation surface 7 are each formed linearly. The first heat radiation surface 6 and the sixth heat radiation surface 7 are continuous so as to form a predetermined angle. End faces 8 are formed at both ends of the radiation fin 3 in the length direction.
One end face 8 and the first heat dissipation face 6 are continuous, and the other end face 8 and the second heat dissipation face 7 are continuous. The thickness of a portion corresponding to a connection region between the first heat radiation surface 6 and the second heat radiation surface 7 is set to the thickness T2. In addition,
The thickness T3 is the same as the dimension of the end face 8 in the arrangement direction of the radiation fins 3. As described above, the radiation fin 3 shown in FIG.
It has an outer peripheral shape such that its thickness decreases from substantially the center in the length direction to both ends. That is, in a plane in the arrangement direction of the heat radiation fins 3, each heat radiation fin 3 has a substantially rhombic outer peripheral shape. In other words,
The thickness of the heat radiation fins 3 is gradually reduced from the center in the length direction to both ends. The heat sink 1 constructed as described above
Are arranged in a state in which heat can be exchanged between the base portion 2 and a heating element (not shown), for example, in a state in which the base portion 2 and the heating element are in close contact with each other. Examples of the heating element include a drive module for a motor that drives a blower for adjusting a flow rate of an automobile air conditioner. Here, as shown in FIG. 1, the heat generation center W <b> 2 of the heat generator contacts the base portion 2 in a region corresponding to substantially the center in the length direction of the radiation fin 3. When the heat of the heating element is transmitted to the base portion 2, the heat is transmitted from the base portion 2 to the radiating fins 3 and the surface of the radiating fins 3, that is, the radiating surface 5
Heat is transferred at the boundary between the end face 8 and the air, and the heat of the radiation fins 3 is radiated into the air. Thus, the temperature rise of the heating element is suppressed, or the heating element is cooled. Next, the heat conduction effect inside the radiation fins 3, particularly the heat conduction effect in a plane (cross section) in the arrangement direction of the radiation fins 3 will be described in detail. As described above, since the heat generation center of the heat generating element is in contact with the base portion 2 in a region corresponding to substantially the center in the length direction of the heat radiation fins 3, in each heat radiation fin 3, the region having the highest temperature, that is, The heat generation center W2 is located substantially at the center of the radiation fin 3 in the length direction. Inside each radiation fin 3,
The heat of the heat generation center W2 is conducted outward. In this case, the temperature distribution in the entire circumferential direction of the heat generation center W2 is substantially uniform, and if this is schematically observed, it can be shown as a substantially circular isotherm. However, the radiation fin 3 shown in FIG.
Since the length L2 is set longer than the thicknesses T2 and T3, the heat conducted from the heat generation center W2 to the inside of the heat radiation fin 3 reaches the heat radiation surface 5 first, and then the end surface 8
To reach. That is, on the heat dissipation surface 5 side, the heat dissipation surface 5
While heat is transmitted between the air and the air, heat conduction inside the heat radiation fins 3 is continued in the area other than the heat radiation surface 5. As a result, rather than the heat transfer action near the heat radiating surface 5,
The heat transfer action in the region other than the heat radiating surface 5 proceeds faster, and the temperature distribution indicated by the isotherm becomes an elliptical shape centered on the heat generation center W2, as indicated by the isotherm D1 shown in FIG. Specifically, the temperature distribution is such that the single axis of the elliptical isotherm D1 is oriented in the thickness direction of the radiation fin 3. In this embodiment, the heat radiating surface 5 has the first heat radiating surface 6 and the second heat radiating surface 7, and the heat radiating fin 3 extends in the longitudinal direction from the region where the heat generating center W2 is located. The thickness of the radiation fin 3 is reduced toward the end face 8 side. The first heat radiating surface 6 and the second heat radiating surface 7 are continuous so as to form a predetermined angle. Therefore, when the elliptical isotherm D1 is generated, the isotherm D1
And the first heat radiating surface 6 and the second heat radiating surface 7 are almost simultaneously and at two places, in other words, two regions E1 and F1.
Touch with. That is, on one heat radiation surface 5, the substantial heat radiation regions E1, F1 are evenly distributed around the heat generation center W2, and heat is transmitted from the respective regions E1, F1 into the air. At a certain point in the heat conduction process corresponding to a predetermined isotherm, specifically, at a point in time when the isotherm and the heat radiating surface come into contact, the heat sink 1 of the embodiment and the heat radiating surface of the heat radiating fins are substantially The heat sink of the comparative example formed in a straight line, specifically, the heat sink 10 shown in FIG.
In comparison with 0, the number of contacts between one isotherm and the heat radiation surface is smaller in the example. That is, the heat sink 1 of the example has a smaller temperature difference on the heat radiation surface in a direction orthogonal to the arrangement direction of the heat radiation fins than the heat sink 100 of the comparative example. Therefore, the embodiment has a higher heat transfer coefficient and an improved heat dissipation performance. On the other hand, in the heat sink 1, the larger the temperature difference between the heat radiation surface 5 and the air, the higher the heat transfer coefficient. Then, air is sent in a direction parallel to the surface 4 of the base portion 2, for example, in the direction of the arrow H <b> 1 toward each space between the heat radiation fins 3 by a compressor or a blower. By generating forced convection in the above, it is possible to adopt a system for increasing the temperature difference between the heat radiation surface 5 and the air as much as possible. In this embodiment, each radiating fin 3
The thickness T3 at both ends in the length direction is set smaller than the thickness T2 at the center in the length direction of the radiation fin 3. In other words, the gap G1 between the radiation fins 3
In each of the radiation fins 3, both ends in the longitudinal direction are wider than the center in the longitudinal direction of the radiation fins 3. For this reason, when air is sent between the radiating fins 3 as described above, the amount of air colliding with the end face 8 and rebounding is reduced, and the amount of air entering the gap G1 can be increased as much as possible. In addition, a decrease in the flow velocity of the air can be suppressed. That is, the resistance when sending air into the gap G1 is reduced as much as possible. Therefore, the temperature difference between the heat radiating surface 5 and the air can be controlled more greatly,
The heat radiation performance of the heat sink 1 is further improved. As shown in FIG. 1, the thickness T2 at the center in the length direction of the radiation fin 3 is changed to the thickness T at both ends in the length direction.
The radiating fin 3 set thicker than 3 is obtained by removing both ends of the radiating fin of the comparative example in which the thickness of the radiating fin is set to be uniform in the length direction of the radiating fin. Accordingly, the metal material can be reduced as compared with the heat sink of the comparative example, so that the manufacturing cost can be reduced, and the weight of the entire heat sink can be reduced by the amount of the removed metal material. FIG. 3 is a plan view showing another embodiment of the radiation fins 3. FIG. The heat radiating surfaces 5 of the heat radiating fins 3 are each set in a substantially arc shape. The thickness T2 of the central region in the length direction of the radiation fin 3 is
Is set to be thicker than the thickness T3 at both ends in the length direction. That is, the thickness of the heat radiation fins 3 gradually decreases from substantially the center in the length direction to both ends. Thus, the planar shape of the radiation fins 3 is set to be substantially elliptical. The other configuration of FIG. 3 is the same as the configuration of the embodiment of FIG. 1 and FIG. In the embodiment shown in FIG. 3, when the heat of the heat generating center W2 is transmitted to the surroundings, an isothermal line D indicating the temperature distribution thereof is obtained.
A part of the shape of the heat radiation surface 5 and a part of the shape of the heat radiation surface 5 substantially match over a predetermined length. In other words, in the embodiment of FIG. 3, the number of locations that substantially contributes to heat radiation on one heat radiation surface 5 is one in the region J1, but the length of the region J1 is as long as possible. Area J1
Is larger than the area of the region B1 substantially involved in heat dissipation in the comparative example shown in FIG. 4, and the heat transfer fin 3 of the embodiment has a lower heat transfer coefficient between the heat dissipation surface 5 and the air. high. In the embodiment of FIG. 3, the other operation and effects are the same as those of the embodiment of FIG. In the embodiment shown in FIGS. 1 and 3, the heat generation center W2 is located substantially at the center of the radiation fin 3 in the longitudinal direction.
Is set, the thickness T2 substantially at the center in the length direction of the radiating fin 3 is the maximum thickness of the radiating fin 3, but the center of heat generation is from the center in the length direction of the radiating fin.
If it is located near one of the ends, the thickness corresponding to the position of the heat generation center is set to the maximum in the length direction of the radiation fin, and the thickness of the area other than the position of the heat generation center is set to the maximum. Is set to be smaller than the thickness. in this way,
The position of the heat generation center is set in a region other than the center in the length direction of the heat radiation fin, the thickness of the region corresponding to the position of the heat generation center is set to the maximum, and the thickness of the other region is set to be greater than the thickness. 1 or 3, the number of contact points between the isotherm and the heat radiating surface is increased or the substantial heat radiating area of the heat radiating surface on one side is increased. Similar effects can be obtained. Here, the correspondence between the configuration of this embodiment and the configuration of the present invention will be described. The heat generating center W2 corresponds to the center of the heat generating element of the present invention. As described above, according to the present invention,
Since the thickness of the region corresponding to the center of the heating element in the direction orthogonal to the arrangement direction of the radiation fins is set to be thicker than the thickness of the region corresponding to the region other than the center of the heating element. At some point during the heat conduction process inside the radiating fin, the number of contact points between one isotherm and the radiating surface decreases, and the temperature difference of the surface of the radiating fin in a direction orthogonal to the arrangement direction of the radiating fins. Is reduced.
Therefore, the heat transfer coefficient is improved over the entire heat radiation surface of the heat radiation fin, and the heat radiation performance of the heat sink is improved.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic plan view showing an example of a heat sink according to the present invention. FIG. 2 is a perspective view showing an example of a heat sink according to the present invention. FIG. 3 is a schematic plan view showing an example of a radiation fin used in the heat sink of the present invention. FIG. 4 is a schematic plan view showing an example of a conventional heat sink. [Description of Signs] 1 ... heat sink, 2 ... base part, 3 ... radiation fins, 5 ... radiation surface, T2, T3 ... thickness, W2 ... heat generation center.

Claims (1)

Claims 1. A base unit capable of exchanging heat with a heating element, and a plurality of radiating fins provided on the base unit. In the heat sink on which the heat radiating surface is formed, the thickness of each of the heat radiating fins in the arrangement direction of the heat radiating fins is a thickness of a region corresponding to a substantially center of the heating element in a direction orthogonal to the arrangement direction of the heat radiating fins. The thickness of the heat sink is set to be thicker than that of a region corresponding to a region other than substantially the center of the heating element.