JP2012231017A - Heat sink - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the performance of a heat sink while avoiding an increase of a pressure loss.SOLUTION: On a radiation unit 3 of a heat sink 1, a plurality of fins 31 are disposed with predetermined gaps in an arrangement direction. Between the side faces of neighboring fins 31, a plurality of slit-shaped flow channels 30 having openings at each front end, rear end and tip end of the fins 31 are formed with sections to extend to a longitudinal direction. Each opening at the tip end of the slit-shaped flow channels 30 is virtually blocked by a duct inner wall 4. At least one side face of each fin 31, at least in an area on the tip end side excluding an area on the base end side, there is performed a heat transfer enhancement work 5 that enhances heat transfer by making a turbulent flow inside the slit-shaped flow channels 30.

Description

  The technology disclosed herein relates to a heat sink that cools a heating element.

  Conventionally, as described in, for example, Patent Document 1, a plurality of fins are attached to a base to which a heating element is attached, and cooling air flows through a slit-like channel formed between adjacent fins. A heat sink that dissipates the heat of the heating element by heat transfer through each fin is known. In such a heat sink, since the temperature of the fin decreases as it goes from the proximal end to the distal end, relatively increasing the flow rate on the proximal end side of the fin in each slit-like channel improves the performance of the heat sink. Will be advantageous. The base end of the fin is the end attached to the base, and the tip of the fin is the end opposite to the base end in the height direction of the fin standing on the base. In the heat sink described in Patent Document 1, as shown in FIGS. 3 and 4, a large number of other fins orthogonal to the fins are attached to the front end side of each fin, and thereby, in the slit-like flow path The distal end side has a smaller channel cross-sectional area, and the proximal end side has a larger channel sectional area. Due to the size of the cross-sectional area of the flow path, the flow rate ratio of the cooling air flowing into the flow path from the opening at the upstream end of the slit-shaped flow path is relatively small on the distal end side and relatively large on the proximal end side. Like that. In this configuration, although the flow rate is reduced on the tip side in the slit-like flow path and the heat transfer coefficient is reduced, the flow rate of the cooling air is reduced by increasing the heat transfer area with a large number of orthogonal fins attached to the tip side. To compensate.

  Further, in Patent Document 2, in order to avoid a decrease in the temperature of the fin on the tip side, the plate thickness on the base end side of each fin is relatively thick, while the plate thickness on the tip side is relatively thin. A heat sink is described. This configuration increases the overall heat transfer efficiency by efficiently conducting the heat received by the base to the tip of the fin, and relatively thins the plate thickness on the tip side. Since the flow path width of the path is not narrowed and the flow path cross-sectional area of the heat sink can be ensured more than a predetermined value, this is also advantageous for improving the performance of the heat sink.

  Furthermore, in Patent Document 3, a large number of triangular pyramid-shaped protrusions are regularly arranged over the entire surface from the proximal end to the distal end on each of both side surfaces of each fin. A heat sink is described in which the heat transfer rate is increased by turbulent flow. Patent Document 3 also describes a heat sink in which the above-described protrusion is provided on a fin whose plate thickness gradually decreases from the base end side toward the front end side, like the heat sink of Patent Document 2 described above.

  In addition, Patent Document 4 describes dimple processing, overhang processing, and offset processing as heat transfer enhancement processing that promotes heat transfer by making the flow in each slit-shaped flow path turbulent, A heat sink is described in which such heat transfer enhancement processing is performed on a part of each fin in the flow direction in accordance with the calorific value distribution of the heating elements arranged side by side in the cooling air flow direction.

JP 2000-260916 A Japanese Patent Laid-Open No. 11-354694 JP 2001-332883 A Japanese Patent No. 4585881

  By the way, with regard to the performance of the heat sink such as reduction of the peak temperature, there is a demand for an improvement in performance over the heat sink described in each patent document. There is a limit. In particular, in a forced air cooling type heat sink in which a heat sink is disposed in a duct and cooling air from a blower source is supplied to the heat sink, it is also required to improve the performance and suppress the pressure loss to a predetermined level or less. Therefore, it is necessary to improve the performance of the heat sink while avoiding an increase in pressure loss. In this regard, the configuration in which the orthogonal fins are attached as described in Patent Document 1 increases the pressure loss significantly by reducing the cross-sectional area of the flow path when the area of the orthogonal fins is increased to improve the performance of the heat sink. become. In addition, a configuration in which a large number of protrusions are attached to the entire surface of both sides of the fin as described in Patent Document 3 to turbulently flow in the slit-shaped flow path is also used to improve the performance of the heat sink. Increasing the number greatly increases the pressure loss of the heat sink.

  The technology disclosed herein has been made in view of such a point, and an object thereof is to improve the performance of the heat sink while avoiding an increase in pressure loss.

  The technology disclosed herein includes a base having an attachment surface and a heat dissipation surface, and at least one heating element attached to the attachment surface, and a plurality of fins erected on the heat dissipation surface of the base. And a heat sink provided in a duct through which cooling air flows.

  And each said fin is extended toward the front-end | tip from the base end which contact | abuts to the said heat radiating surface so that it may protrude from the said heat radiating surface, From the front end corresponding to the upstream end in the flow direction of the said cooling air, It extends in the front-rear direction toward the rear end corresponding to the downstream end, and the plurality of fins are arranged at predetermined intervals in the arrangement direction orthogonal to the front-rear direction in the heat dissipation part. Between the side surfaces of adjacent fins, a plurality of slit-like channels that open at each of the front end, the rear end, and the tip of the fin are partitioned and formed so as to extend in the front-rear direction. The opening at the distal end of the fin is substantially closed by the inner wall of the duct, and at least one side surface of each fin has the slit at the distal end region excluding at least the proximal end region. Heat transfer enhancement processing to facilitate the heat transfer is applied by the flow of bets like passage to turbulence.

  Here, the heat transfer acceleration process may be a process for forming a protrusion protruding from the side surface of the fin by dimple processing, overhanging processing, offset processing, or the like as described in Patent Document 4, for example. Moreover, it is good also as a process which attaches such a protrusion to the side surface of a fin using various joining methods. The protrusions make the flow in the slit channel turbulent, and the effect of the turbulent flow promotes heat transfer. The heat transfer enhancement processing may be performed over the entire region from the front end to the rear end of the fin in the region on the front end side excluding the region on the base end side, or after the temperature of the cooling air increases in the region on the front end side. Even if heat distribution enhancement processing is applied only to the end part, the part from the central part to the rear end part, or the part where the heat generation amount is relatively high when the distribution of heat generation amount exists in the front-rear direction. Good.

  According to this configuration, at least one side surface of each fin that divides the slit-shaped flow path in the heat radiating portion of the heat sink has a flow in the slit-shaped flow path in a region on the distal end side except at least a region on the proximal end side. Heat transfer enhancement processing is applied to promote heat transfer by making the turbulent flow. In other words, since the heat transfer promoting process is not performed on the base end side region of the side surface, the base end side in the slit-like flow path has a relatively large flow path cross-sectional area, while heat transfer promotion is performed. The flow path cross-sectional area is relatively small on the tip side where the processing is performed. Thus, the flow path cross-sectional areas are different between the proximal end side and the distal end side in the slit-shaped flow path, so that the flow rate on the proximal end side is relatively large and the flow rate on the distal end side is relatively small. Since the flow rate on the base end side where the temperature of the fin is relatively high becomes large, this configuration is advantageous in improving the performance of the heat sink.

  In addition, turbulent flow is generated in the slit-like channel on the tip side where heat transfer enhancement processing is performed, and the heat transfer rate is improved. For this reason, although the flow rate of the cooling air is relatively small at the tip end side of the fin, a decrease in heat transfer efficiency is suppressed.

  Thus, the turbulent flow is generated at the front end side in the slit-shaped flow path, so that the cooling air flowing in the slit-shaped flow path is in a direction other than the front-rear direction (in other words, the flow direction of the cooling air in the duct). The velocity component in the direction from the proximal end of the fin toward the distal end and in the direction from the distal end of the fin opposite to the proximal end is also provided. Here, the heat sink is disposed in the duct, and the opening at the tip of the slit-like channel is substantially blocked by the inner wall of the duct, and the cooling air in the slit-like channel escapes through this opening. I can't. For this reason, in the slit-like flow path, the flow in the direction from the tip end of the fin to the base end is promoted by the generation of turbulent flow. That is, the flow velocity in the slit-like flow path on the proximal end side is promoted by promoting the flow in the direction from the front end to the proximal end in the slit-like flow path, in other words, in the middle of the flow path in the front-rear direction. Increased speed. As a result, as described above, the flow rate on the base end side is increased and the pressure loss is increased more than the effect of increasing the flow rate on the base end side obtained by the difference in the cross-sectional area between the base end side and the front end side as described above. Is avoided. Further, the above-described flow speed increase becomes remarkable particularly on the rear side of the heat sink, which is advantageous in reducing the peak temperature. Therefore, the performance of the heat sink having this configuration is improved while avoiding an increase in pressure loss.

  Each fin may have a thickness on the base end side that is thicker than a thickness on the tip side.

  By reducing the plate thickness on the base end side of the fin and relatively reducing the plate thickness on the tip side, it is possible to suppress the temperature of the fin from decreasing toward the tip. This is advantageous for improving the performance of the heat sink.

  Moreover, by making the plate | board thickness of the base end side of a fin comparatively thick, the flow path width of a slit-shaped flow path becomes narrow at the base end side. Therefore, although it becomes difficult for the cooling air to flow on the proximal end side of the slit-shaped flow path, as described above, the heat transfer enhancement processing on the distal end side causes the flow in the direction from the distal end to the proximal end inside the slit-shaped flow path. By promoting, it is possible to increase the flow rate on the proximal side. As a result, the performance of the heat sink is improved while avoiding an increase in pressure loss of the heat sink.

  As described above, the heat sink is subjected to heat transfer enhancement processing at least on the distal end side region except for the proximal end region on the side surface of each fin, so that the opening at the distal end of the slit-shaped channel is the inner wall of the duct. The flow in the direction from the tip end of the fin to the base end is promoted inside the slit-like channel, and the flow velocity on the base end side of the slit-like channel is increased. The flow rate can be further increased. As a result, the heat sink having this configuration is realized to avoid an increase in pressure loss, and the performance is improved by combining the increase in the flow rate on the proximal end side and the turbulent flow effect on the distal end side.

It is a perspective view of a heat sink. (A) Front view of heat sink, (b) Side view of heat sink, (c) Bottom view of heat sink. FIG. 3A is a front view of a heat sink having a different configuration from that of FIG. It is a figure explaining the process of the fin shown in FIG. (A) The contour figure of the velocity distribution in the slit-shaped channel which concerns on a comparative example, (b) The contour diagram of the velocity distribution in the slit-shaped channel which concerns on an Example.

  Hereinafter, an embodiment of a heat sink will be described based on the drawings. In addition, the following description of preferable embodiment is an illustration. FIG. 1 shows a perspective view of the heat sink 1, FIG. 2 shows a front view of the heat sink, (b) a side view of the heat sink, and (c) a bottom view of the heat sink. . The heat sink 1 is a cooler for cooling the heating element 2 such as a power semiconductor element used for driving a railway vehicle. However, it may be used for other purposes. Although not shown in detail, the heat sink 1 is disposed in a duct, and cooling air from a blower (not shown) connected to the duct is supplied to the heat sink 1. That is, the heat sink 1 is a forced air cooling type heat sink 1, and the heat sink 1 radiates the heat of the heating element 2 to cool the heating element 2. The heat sink 1 includes a base 11 to which the heating element 2 is attached, and a heat radiating unit 3 including a plurality of fins 31 erected with respect to the base 11.

  The base 11 is a flat plate having a predetermined thickness while extending in the front-rear direction corresponding to the direction of the duct and the direction orthogonal to the front-rear direction, and the mounting surface 111 on which the heating element 2 is mounted and the fins 31 stand upright. The heat dissipating surface 112 to be provided is configured to face in the thickness direction. A plurality of heating elements 2 are attached to the attachment surface 111 of the base 11 in contact with the attachment surface 111 with grease having high thermal conductivity interposed therebetween. In the illustrated example, a total of twelve heating elements 2 are arranged in a matrix so that there are four in the front-rear direction and three in the arrangement direction. The number of heating elements 2 and the arrangement thereof are not particularly limited.

  Also, a plurality of heat pipes 12 extending in the arrangement direction are embedded in the base 11 with a predetermined interval in the front-rear direction. In the illustrated example, a total of eight heat pipes 12 are embedded so that two heat pipes 12 correspond to one heating element 2. Here, as shown in FIG. 2C, the heating elements 2 arranged on one side (upper side in the figure) of the arrangement direction have a relatively large thermal load, while the other side ( The heat generating element 2 arranged on the lower side in the figure has a small heat load. As described above, combining the heat pipes 12 extending in the arrangement direction with the heating elements 2 having different heat loads is advantageous in order to equalize the heat generation elements 2 in the arrangement direction. The heating elements 2 arranged in the middle of the arrangement direction can have large, small, and medium heat loads.

  Each fin 31 is a flat plate having a certain thickness, and is perpendicular to the heat radiating surface 112 from the base end contacting the heat radiating surface 112 of the base 11 to the tip (that is, in the height direction). In addition to being erected on the heat radiating surface 112 so as to extend in the vertical direction, it extends in the front-rear direction. The shape of each fin 31 is not limited to the illustrated example, and the ratio of the height, the length in the front-rear direction, and the thickness can be set as appropriate.

  The plurality of fins 31 are arranged in parallel with the heat dissipating surface 112 of the base 11 at predetermined equal intervals in the arrangement direction. In the illustrated example, eleven fins 31 are arranged side by side, but the number of fins 31 of the heat dissipating unit 3 is not limited to this. A slit-like flow path 30 extending along the front-rear direction is defined between the side surfaces of the adjacent fins 31 in the heat radiating unit 3. Each slit-like channel 30 opens at each of the front end (the left front end in FIG. 1), the rear end (the right back end in FIG. 1), and the front end (the upper end in FIG. 1) of the fin 31. However, as virtually shown in FIGS. 2A and 2B, the opening at the tip of each slit-like channel 30 is closed by the inner wall 4 of the duct. It should be noted that the end of each fin 31 and the inner wall 4 of the duct are not only closed by the abutment of the inner wall 4 of the duct at the tip of each fin 31 but the opening of the end of each slit-like flow path 30 is completely closed. However, a configuration in which the opening at the tip of each slit-like channel 30 is substantially blocked may be employed. In addition, the channel width of the slit-shaped channel 30 can be set to an appropriate width, and is not limited to the illustrated example.

  The heat sink 1 is formed of a material having high thermal conductivity, such as aluminum or an aluminum alloy. The heat sink 1 may be formed by joining the fins 31 to the base 11 by various appropriate means such as welding, brazing, and adhesive.

  The most characteristic point of this heat sink is that one side of each fin 31, that is, one side, is subjected to heat transfer enhancement processing 5 that generates turbulent flow in the slit-like flow path 30 and promotes heat transfer. Yes. This heat transfer enhancement processing 5 is applied to the tip end region excluding the proximal end region of the fin 31 in the slit-shaped flow path 30 and from the center, excluding the front side in the front-rear direction in the illustrated example. It is given to the part over the back side. More specifically, when the fin 31 is divided into three in the height direction, the heat transfer promoting process 5 is applied to the region from the central portion to the tip portion, and when the fin 31 is divided into three in the front-rear direction. A heat transfer enhancement process 5 is generally performed in a region from the center to the rear.

  Specifically, the heat transfer enhancement processing 5 is configured by a plurality of convex portions 51 provided so as to protrude from the side surfaces of the fins 31. The convex portion 51 may be formed by press molding, for example. In this case, in each fin 31, a concave portion 52 is formed on the side surface opposite to the side surface from which the convex portion 51 projects.

  As shown in FIG. 2B, the plurality of convex portions 51 are arranged in a row by arranging three or four in the height direction, and the rows are arranged in front and rear. It is arranged so that four rows are formed at predetermined intervals in the direction. In the following, for convenience of explanation, the columns formed by the convex portions 51 are referred to as a first column, a second column, a third column, and a fourth column in order from the front side to the rear side.

  Each convex portion 51 is formed in a rectangular shape in a side view, and a predetermined gap is provided between the convex portions 51 adjacent to each other in the height direction in each row. Here, each of the first row and the third row is constituted by three convex portions 51, whereby the first row and the third row have two gaps, while the second row and the fourth row. Is constituted by four convex portions 51, whereby the second row and the fourth row have three gaps. For this reason, when it sees in the front-back direction, it arrange | positions so that the clearance gap of each row | line | column may become alternate in a height direction. Such an arrangement of the convex portions 51 is advantageous in increasing turbulent turbulence.

  In this way, the heat transfer enhancement processing 5 that promotes heat transfer by making the flow in the slit-like flow path 30 turbulent in the region on the distal end side excluding the region on the proximal end side on the side surface of each fin 31. As a result, the flow path cross-sectional area is relatively small on the distal end side in the slit-shaped flow path 30, while the flow path cross-sectional area is relatively small on the base end side where the heat transfer promotion processing 5 is not performed. (See FIG. 2A). As a result, the flow rate on the proximal end side is relatively large, the flow rate on the distal end side is relatively small, and the flow rate of the cooling air flowing on the proximal end side where the temperature of the fins 31 is relatively high is large. Therefore, the heat dissipation effect is enhanced, which is advantageous for improving the performance of the heat sink 1.

  In addition, although the flow rate of the cooling air is small on the front end side, the heat transfer rate is improved by the turbulent flow generated by the heat transfer promotion processing 5, and thus the decrease in heat transfer efficiency on the front end side is suppressed.

  Then, when turbulent flow is generated on the distal end side in the slit-shaped flow path 30, the cooling air flowing in the slit-shaped flow path 30 is supplied from the base end of the fin 31 in addition to the velocity component in the front-rear direction. It also has a velocity component in the direction toward the tip and in the direction from the tip of the fin 31 opposite to the tip toward the base. However, as described above, the heat sink 1 is disposed in the duct, and the opening at the front end of the slit-shaped flow path 30 is blocked by the inner wall 4 of the duct. You can't escape outside through. As a result, in the heat sink 1, the flow in the direction from the tip end to the base end of the fin 31 is promoted in the slit-like flow path 30. As a result, the flow on the proximal end side is accelerated, and the flow rate on the proximal end side of the slit-like flow path is increased more than making the flow path cross-sectional areas different between the distal end side and the proximal end side. Thus, the heat sink 1 can avoid an increase in pressure loss, and can improve performance while avoiding an increase in pressure loss.

  Further, by applying the heat transfer enhancement process 5 to the portion excluding the front side in the front-rear direction, the heat transfer rate can be increased on the rear side where the temperature of the cooling air is increased, and the rear side of the slit-like flow path 30 is increased. It becomes possible to increase the flow velocity. This is advantageous for reducing the peak temperature, and improves the performance of the heat sink 1 more effectively. In particular, as shown in FIG. 2 (c), combining with the soaking in the alignment direction by the heat pipe 12, it is further advantageous for the reduction of the peak temperature. Note that the heat pipe 12 can be omitted depending on the arrangement of the heating elements 2.

  In addition, the range which performs the heat transfer acceleration | stimulation process 5 is not limited to the part from a center part to a rear side, as mentioned above, You may perform a heat transfer acceleration | stimulation process only to a rear side, Heat transfer enhancement processing may be performed over almost the entire direction. Moreover, in FIG. 2, when the fin 31 is divided into three in the height direction, the heat transfer promoting process 5 is applied to the region from the central portion to the tip portion. You may give the heat-transfer acceleration | stimulation process 5 to the part at the front end side when dividing into 2 in a height direction. Similarly, in the illustrated example, the heat transfer promoting process 5 is applied to the region from the center to the rear when roughly divided into three in the front-rear direction, but the rear part when divided into two in the front-rear direction The heat transfer acceleration processing 5 may be applied to the. In addition, in the front-rear direction, in addition to such divisions as three divisions and two divisions, if there is a heat generation distribution in the front-rear direction, the heat transfer enhancement processing 5 is applied to the portion where the heat generation amount is relatively high. You may give it.

  Moreover, the heat transfer acceleration | stimulation process 5 should just set the shape suitably not only in forming the rectangular convex part 51 as mentioned above. For example, a circular convex portion may be formed. In addition, as the processing method, dimple processing, overhang processing, and offset processing may be appropriately employed.

  Furthermore, the shape of the fin 31 is not limited to the plate thickness being constant in the height direction as described above, and the plate thickness may be changed in the height direction. FIG. 3 shows another configuration example of the heat sink 10, (a) is a front view, and (b) is a side view. In addition, the same code | symbol is attached | subjected about the part of the structure substantially the same as the heat sink 1 shown in FIG. As shown in FIG. 3, in each fin 310, the thickness of the region on the base end side where the heat transfer enhancement processing 5 is not performed is thicker than the thickness of the region on the distal end side where the heat transfer enhancement processing 5 is performed. . More specifically, the region on the proximal end side of each fin 310 is configured such that its plate thickness gradually decreases from the proximal end side toward the distal end side, while the region on the distal end side has its plate thickness. It is configured to be constant. In addition, the fin 310 is configured such that one side surface (the left side surface in FIG. 3A) is flat, and the base end side on the other side surface (the right side surface in the figure) Inclined so that the plate thickness is changed.

  Such a configuration is advantageous for processing the fin 310. That is, when the heat transfer enhancement processing 5 is performed by press molding, as shown in FIG. 4A, a flat side surface (hereinafter referred to as the lower surface) is placed on the lower press stand 71 in the press molding machine 7. Thus, it is possible to place the fin 310 before molding. Further, as shown in FIG. 4B, the punch 73 protrudes upward from the surface of the lower press stand 71 and the die 72 that presses the other surface (referred to herein as the upper surface) of the fin 310 is used. The convex part 51 which protrudes from an upper surface can be formed. Therefore, since only the concave portion 52 is formed on the lower surface of the fin 310, the fin 310 can be stably placed on the lower press stand 71 even after the convex portion 51 is formed. This makes it possible to transport the fin 310 before molding while sliding on the lower press table 71 and to transport the fin 310 after molding while sliding on the lower press table 71. Further, it is not necessary to provide the “escape” of the formed convex portion 51 on the lower press stand 71, and a general-purpose press molding machine can be used as it is. Furthermore, since the lower surface of the fin 310 is flat, there is also an advantage that the fins 310 can be easily arranged at regular intervals. As a result, there is an advantage that the processing cost of the fin 310 is reduced.

  Thus, while the plate thickness on the proximal end side of the fin 310 is relatively thick, the plate thickness on the distal end side is relatively thin, so that the temperature of the fin 310 decreases toward the tip. . As a result, it is advantageous for improving the performance of the heat sink 10.

  Further, as shown in FIG. 3A, the flow path width of the slit-shaped flow path 300 becomes narrower on the base end side as the fin thickness on the base end side of the fin is increased, and the cooling air is generated. It becomes difficult to flow. However, the heat transfer acceleration processing 5 applied to the tip side of the fin 310 can increase the flow rate on the base end side in the slit-like channel 300 and increase the flow rate. However, it is possible to further improve the performance while avoiding an increase in pressure loss.

Furthermore, the heat transfer enhancement processing is not limited to the one surface of the fins 31 and 310 but may be performed on both surfaces of the fins 31 and 310.

Next, practical examples relating to the pressure loss and performance of the heat sink will be described. First, as evaluation regarding the region where heat transfer enhancement processing is performed, heat sinks according to the conventional example, the comparative example, and the example were created, and the pressure loss Δp and the performance of the heat sink were compared with each other. Here, the performance of the heat sink is evaluated by the temperature difference Δt at the downstream end of the base of the heat sink with respect to the temperature of the cooling air flowing into the heat sink. Although not shown in the drawings, the conventional example is an example in which heat transfer acceleration processing is not applied to the fin, the comparative example is an example in which heat transfer acceleration processing is applied to the entire fin from the base end to the tip, and the embodiment is a fin. In this example, heat transfer enhancement processing is not performed on the base end side, and heat transfer enhancement processing is performed only on the distal end side. In addition, about other conditions, a prior art example, a comparative example, and an Example are mutually the same. The results are as follows.
Example: Δp = 216 Pa, Δt = 40.8 ° C.
Comparative example: Δp = 273 Pa, Δt = 40.5 ° C.
Conventional example: Δp = 144 Pa, Δt = 44.4 ° C.
First, when the conventional example is compared with the examples and comparative examples, the performance of the conventional example is significantly lower, although the pressure loss is smaller than that of the examples and comparative examples. Next, when comparing the example and the comparative example, there is almost no difference in performance between the example and the comparative example, but the pressure loss is much smaller in the example than in the comparative example. In other words, the embodiment in which heat transfer acceleration processing is applied to the distal end side and not applied to the proximal end side has the same performance as the comparative example in which the heat transfer acceleration processing is performed over the entire length from the distal end to the proximal end, and is smaller. It can be achieved with pressure loss.

  Next, simulation was performed as evaluation regarding the speed-up effect on the base end side in the slit-like flow path by heat transfer enhancement processing. This simulation is an example in which the cross-sectional area of the flow path is changed between the front end side and the base end side of the slit-shaped flow path by providing orthogonal fins on the front end side of the fins as described in Patent Document 1 (comparison) Example) and a slit-shaped flow path in which the cross-sectional area of the flow path is changed between the distal end side and the proximal end side of the slit-shaped flow path by applying heat transfer enhancement processing to the front end side of the fin (Example) The flow velocity distribution inside is simulated. The slit-shaped channel has an opening at its front end (left end in FIG. 5) and rear end (right end in FIG. 5), and its tip (upper end in FIG. 5) is closed. Further, in the comparative example and the example, the conditions at the inlet of the slit-like flow path are made to coincide with each other, and the conditions are arranged so that the pressure loss also almost matches with each other. The pressure loss is 169 Pa in the comparative example and 163 Pa in the example.

  FIG. 5 shows a contour diagram of the velocity distribution according to the simulation result. This contour diagram shows the velocity distribution in the central section in the width direction of the slit-like flow path. Here, for the sake of easy understanding, focusing on the flow velocity on the base end side, only the portion (7. 88-13.79 m / s), (13.79-15.76 m / s), (15.76-17.73 m / s) and (17.73-19.7 m / s) It is attached.

  (A) of FIG. 5 relates to a comparative example, and as shown in the left figure, orthogonal fins 61 protruding from the side surfaces of the fins are arranged continuously extending in the front-rear direction. It arrange | positions so that it may become alternate in a height direction from each of a pair of fin side surface which divides and forms a slit-shaped flow path. In addition, the orthogonal fin 61 is arrange | positioned at the front end side except the base end side, and is arrange | positioned in the part from the center to the rear side except the front side in the front-back direction. On the other hand, FIG. 5B relates to the embodiment, and the convex portions 62 having the same shape as the convex portions 51 shown in FIG. 2 are provided in the same arrangement. 5A and 5B, the range in which the orthogonal fins 61 are provided in the comparative example and the range in which the convex portions 62 are provided in the embodiment are the same as each other. is there.

First, referring to FIG. 5A, in the comparative example, the flow velocity on the base end side where the orthogonal fins 61 are not formed at the position in the front-rear direction corresponding to the distal end of the orthogonal fins 61 in the slit-shaped flow path. The speed is increasing. This is because the cross-sectional area on the distal end side becomes relatively small due to the formation of the orthogonal fins 61, while the cross-sectional area on the proximal end side becomes relatively large. This is probably because the flow rate becomes large. Further, in the comparative example, the flow velocity on the tip side hardly changes. In other words, in the contour diagram, the range of (15.76-17.7.3 m / s) extends in the front-rear direction.

  Next, referring to FIG. 5 (b), in the example as well as in the comparative example, at the position in the front-rear direction corresponding to the tip of the convex portion 62 (the first row described above) in the slit-like flow path. The flow velocity on the base end side is increased. This is considered to be because the flow rate on the base end side becomes large due to the difference in the channel cross-sectional area between the tip end side and the base end side, as in the comparative example. However, in the embodiment, in the region on the base end side, the flow velocity is further increased in the vicinity of the position in the front-rear direction corresponding to the third row described above. That is, in the example, the range of the highest flow velocity (that is, 17.73 to 19.7 m / s) in the region on the base end side is wider in the front-rear direction than the comparative example, and the flow velocity at the rear side of the heat sink is Is clearly faster than the comparative example. This means that the example is more advantageous for reducing the peak temperature than the comparative example. Moreover, since the pressure loss is substantially the same between the example and the comparative example, it can be said that the example has higher performance than the comparative example.

  In the comparative example, the orthogonal fin 61 extends continuously in the front-rear direction, and the flow from the tip end side to the base end side of the fin is promoted with little or no turbulence occurring on the tip side. On the other hand, in the embodiment, by providing a plurality of convex portions in a predetermined arrangement, a strong turbulent flow is generated on the front end side in the slit-shaped channel, and the slit-shaped channel As a result, the flow from the tip side of the fin toward the base end side is promoted in the middle of the slit-like flow path, and the flow velocity at the base end side, particularly the rear side, is thereby closed. Will increase.

  Therefore, applying heat transfer enhancement processing that generates turbulent flow can reduce the flow rate on the base end side more than reducing the cross-sectional area on the front end side in the slit-like flow path by forming orthogonal fins or the like. Increased and more advantageous in avoiding increased pressure loss.

  As described above, since the heat sink disclosed herein can improve the performance of the heat sink while avoiding an increase in pressure loss, it is useful as a heat sink that is disposed in a duct and cools various heating elements. .

DESCRIPTION OF SYMBOLS 1 Heat sink 10 Heat sink 11 Base 30 Slit-like flow path 300 Slit-like flow path 31 Fin 310 Fin 4 Duct inner wall 5 Heat transfer promotion processing 51 Projection

Claims (2)

A base having an attachment surface and a heat dissipation surface, to which at least one heating element is attached to the attachment surface, and a heat dissipation portion including a plurality of fins standing on the heat dissipation surface of the base, A heat sink provided in a duct through which cooling air flows,
Each fin extends from the base end in contact with the heat radiating surface to the front end so as to protrude from the heat radiating surface, and from the front end corresponding to the upstream end in the cooling air flow direction to the downstream end thereof Extending in the front-rear direction toward the rear end corresponding to
In the heat radiating portion, the plurality of fins are arranged at a predetermined interval in an arrangement direction orthogonal to the front-rear direction, so that the front end and rear end of the fins are disposed between the side surfaces of the adjacent fins. A plurality of slit-like flow paths opening at each of the end and the tip are partitioned so as to extend in the front-rear direction,
The opening at the tip of each slit-shaped channel is substantially closed by the inner wall of the duct,
At least one side surface of each fin has heat transfer enhancement processing that promotes heat transfer by making the flow in the slit-like flow path turbulent at least in the region on the distal end side excluding the region on the proximal end side. The heat sink that has been applied. The heat sink according to claim 1.
Each of the fins is a heat sink in which the base end side plate thickness is thicker than the tip end plate thickness.

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