US20070089869A1

US20070089869A1 - Heat sink

Info

Publication number: US20070089869A1
Application number: US11/309,067
Authority: US
Inventors: Ching-Bai Hwang; Xi-Jian Zhu
Original assignee: Foxconn Technology Co Ltd
Current assignee: Foxconn Technology Co Ltd
Priority date: 2005-10-21
Filing date: 2006-06-15
Publication date: 2007-04-26
Also published as: CN1953648A; CN100493317C

Abstract

A heat sink (10) includes a plurality of fins (12). Each of the fins includes a main body (122) and at least one bulge (126) disposed on the main body. The main bodies of two adjacent fins cooperatively define an air passage (121) therebetween, for allowing an airflow to pass therethough. The bulge has a varying projection height so as to form a streamline guide surface (127) thereon.

Description

FIELD OF THE INVENTION

The present invention relates generally to a heat sink, and more particularly to a heat sink for dissipating heat generated by electronic components, wherein fins of the heat sink project bulges therefrom for increasing heat dissipation efficiency of the heat sink.

DESCRIPTION OF RELATED ART

A conventional heat dissipating apparatus includes a heat sink thermally connected with a heat source for absorbing heat therefrom, and a heat dissipating fan for providing an airflow, which flows through the heat sink to take away heat therefrom. The heat sink includes a plurality of fins with two opposite planar surfaces. A plurality of air passages is formed between the fins allowing the airflow to flow therebetween.
When the airflow flowing through the air passages of the heat sink, the airflow is laminar or turbulent. Turbulent airflow increases heat convection efficiency between the fins and the airflow, which further increases heat dissipation efficiency of the heat dissipating apparatus. However, even if the airflow is turbulent, a laminar sublayer is still formed adjacent to the surfaces of the fins where the airflow contacts with the fins. The thickness of the laminar sublayer is gradually increased when the airflow flowing through the air passages of the heat sink. The increase in thickness of the laminar sublayer causes a decrease in heat convection efficiency. Therefore, reducing the laminar sublayer and so improving heat convection efficiency is key in increasing the heat dissipation efficiency of the heat dissipating apparatus.

SUMMARY OF THE INVENTION

The present invention relates to a heat sink for dissipating heat from a heat-generating electronic component. According to a preferred embodiment of the present invention, the heat sink includes a plurality of fins. Each of the fins includes a main body and at least one bulge disposed on the main body. The main bodies of two adjacent fins cooperatively define an air passage therebetween, allowing airflow to pass therethough. The bulge has a varying projection height so as to form a streamline guide surface thereon. Furthermore, the bulge facilitates creating turbulence on surfaces of the fin, thereby increasing heat dissipation effectiveness of the fin when an airflow flows through the fin.
Other advantages and novel features of the present invention will become more apparent from the following detailed description of preferred embodiment when taken in conjunction with the accompanying drawings, in which:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an isometric view of a heat sink according to a preferred embodiment of the present invention;
FIG. 2 is an isometric view of a fin of the heat sink of FIG. 1;
FIG. 3 is an isometric view of a fin of a heat sink according to a second embodiment of the present invention; and
FIG. 4 is an isometric view of a heat sink according to a third embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIGS. 1 and 2, a heat sink 10 according to a preferred embodiment of the present invention is shown. A heat dissipating fan (not shown) is disposed at one side of the heat sink 10, for providing an airflow passing through the heat sink 10 to take away heat therefrom as indicated by arrows of FIG. 1. The heat sink 10 includes a plurality of parallel fins 12 and a heat pipe 14 extending through the fins 12. The heat pipe 14 has two opposite ends respectively connecting with a heat-generating electronic component (not shown) and the fins 12, for transferring heat therebetween.
Each of the fins 12 includes a rectangular shaped main body 122, and two flanges 123 extending from two opposite ends of the main body 122. The fins 12 are stacked together with the flanges 123 of a rear fin 12 abutting against the main body 122 of a front fin 12. A plurality of air passages 121 are formed between two adjacent fins 12 to allow the airflow pass through. The main body 122 of each fin 12 defines a receiving hole 124 at a top portion thereof, for allowing the heat pipe 14 to extend therethrough. A collar 125 extends forwards from a periphery of the receiving hole 124, thus increasing the contacting areas between the fins 12 and the heat pipe 14. The heat convection between the fin 12 and the heat pipe 14 is thus increased due to the collar 125.
Each fin 12 projects a bulge 126 forwards from the main body 122 thereof. The bulge 126 extends from the bottom and right corner of the main body 122 toward the bottom and left side of the heat pipe 14. The extension direction of the bulge 126 is at an obtuse angle to the flow direction of the airflow. The joint of the bulge 126 and the main body 122 is rhombus-shaped in profile. The projection height of the bulge 126 gradually decreases from a center of the bulge 126 toward that of the joint. Two streamline guide surfaces 127 with arrow-shaped profiles are formed on the bulge 126. The guide surfaces 127 extend from two acute corners of the bulge 126 toward a middle portion thereof and join with each other thereat. The profile of the guide surface 127 reduces the air resistance of the bulge 126.
When the airflow reaches the bulges 126 of the fins 12, one part of the airflow strides over the bulges 126, going straight ahead, whilst the other part of the airflow moves towards the heat pipe 14 along the guide surfaces 127 of the bulges 126. There is more airflow flowing toward the heat pipe 14, which removes more heat from the heat pipe 14. The heat dissipation efficiency of the heat sink 10 is thus increased. Moreover, the airflow flowing through the air passages 121 of the fins 12 is deflected by the bulges 126 projecting from the main bodies 122 of the fins 12. The turbulence of the airflow reduces the thickness of the laminar sublayer, which increases the heat convection between the fins 12 and the airflow, and further improves the heat dissipation efficiency of the heat sink 10. In addition, the bulges 126 increase the heat dissipation areas of the fins 12, and further increase the heat dissipation efficiency of the heat sink 10.
Referring to FIG. 3, the fin 12 a of the heat sink 10 of the second embodiment of the present invention is shown. In this embodiment, the main body 122 of the fin 12 a projects three parallel bulges 126 a. The extension lengths of the bulges 126 a decrease from the left side of the main body 122 toward the right side thereof. The bulge 126 a at the left side of the main body 122 extends from the bottom and right corner of the main body 122 toward the bottom and left side of the collar 125, in a manner such that it can guide more airflow to flow toward the heat pipe. Referring to FIG. 4, the third embodiment of the heat sink 10 b of the present invention is shown. The difference between this embodiment from the second embodiment is that the extension directions of the bulges 126 b are different from each other. The bulges 126 b guide the airflow flowing toward the heat pipe 14 along different directions. Air turbulence is thus generated, which increases the heat convection of the fins 12 and the airflow near the heat pipe 14, and further improves the heat dissipation efficiency of the heat sink 10 b. Alternatively, the heat sink may include a plurality of heat pipes, whist the main body of each fin projects a plurality of bulges towards the heat pipes. When the main body of each of the fins projects more than two bulges, the bulges can be arranged on two opposite surfaces of the main body.
In the above mentioned embodiments of the present invention, the joint of the bulge 126 and the main body 122 of the fin 12 has been rhombus-shaped in profile. Alternatively, that joint may be ellipse-shaped or other shaped in profile. When the main body of the fin projects more than two bulges, the joints of the bulges and the main body may have the same or different profiles.
It is to be understood, however, that even though numerous characteristics and advantages of the present invention have been set forth in the foregoing description, together with details of the structure and function of the invention, the disclosure is illustrative only, and changes may be made in detail, especially in matters of shape, size, and arrangement of parts within the principles of the invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.

Claims

1. A heat sink comprising:

a plurality of fins each comprising a main body and at least one bulge disposed on the main body, the main bodies of two adjacent fins cooperatively defining an air passage therebetween for allowing an airflow to pass therethough, the at least one bulge having a varying projection height so as to form a streamline guide surface thereon.

2. The heat sink as described in claim 1, wherein the at least one bulge extends from the main body of the fin towards at least an adjacent fin.

3. The heat sink as described in claim 1, wherein the projection height of the at least one bulge is gradually decreased from a center of the at least one bulge toward the joint of the at least one bulge and the main body.

4. The heat sink as described in claim 1, wherein the profile of the joint between the at least one bulge and the main body is chosen from the group consisting of rhombus-shape, and ellipse-shape.

5. The heat sink as described in claim 1, further comprising a heat pipe thermally connected with the fins.

6. The heat sink as described in claim 6, wherein the at least one bulge extends from a corner of the main body of the fin towards an opposite corner adjacent to the heat pipe.

7. The heat sink as described in claim 1, wherein the extension direction of the at least one bulge forms an obtuse angle to the flow direction of the airflow.

8. The heat sink as described in claim 1, wherein the at least one bulge comprises more than one parallel bulge.

9. The heat sink as described in claim 1, wherein the at least one bulge comprises more than one bulge having a different extension direction.

10. A heat sink adapted for dissipating heat from a heat-generating electronic component comprising:

a plurality of fins each comprising a main body and at least one bulge extending from the main body, the at least one bulge having a projection height gradually decreased from a middle portion of the at least one bulge toward a periphery thereof.

11. The heat sink as described in claim 10, further comprising a heat pipe thermally connected to the fins.

12. The heat sink as described in claim 11, wherein the at least one bulge extends from a corner of the main body of the fin toward an opposite corner adjacent to the heat pipe.

13. The heat sink as described in claim 10, wherein the profile of the periphery of the at least one bulge is selected from the group consisting of rhombus-shape and ellipse-shape.

14. The heat sink as described in claim 10, wherein the at least one bulge has two arrow-shaped guide surfaces formed thereon.

15. The heat sink as described in claim 14, wherein the two guide surfaces have acute corners pointed toward opposite directions and met with each other at a middle of the at least one bulge.

16. A heat sink comprising:

a heat pipe having a first end section adapted for thermally connecting with a heat generating electronic component and a second end section; and

a plurality of fins stacked together, the second end section of the heat pipe extending through the fins and thermally connecting therewith, each of the fins having a main body with an elongated bulge thereon, wherein the elongated bulge extends from a corner of the main body toward the heat pipe.

17. The heat sink of claim 16, wherein the bulge has a height gradually increased from a periphery thereof toward a center thereof.

18. The heat sink of claim 17, wherein the main body comprises an additional bulge having a length smaller than that of the bulge and extending in a direction parallel to that of the bulge.

19. The heat sink of claim 18, wherein the bulge has one of rhombus shape and ellipse shape.

20. The heat sink of claim 17, wherein the main body comprises an additional bulge having a length smaller than that of the bulge and extending in a direction non-parallel to that of the bulge.