Heat sink with heat pipes

A heat sink includes a first plate having a top portion and a bottom portion, a second plate projecting from the top portion of the first plate, and a plurality of fins thermally contacting the second plate. The second plate has a width larger than that of the first plate. The heat pipe includes a first portion embedded in the bottom portion of the first plate for directly contacting an electronic component to be cooled, and a second portion bent from one end of the first portion. The second portion is located at one side of the first plate, while the first portion of the heat pipe is located at a middle of the first plate.

FIELD OF THE INVENTION

The present invention relates to a heat sink for removing heat from heat-generating electronic devices, and more particularly to a heat sink having heat pipes embedded therein.

DESCRIPTION OF RELATED ART

Over the past few years, CPU's operation speeds have been increasing at a dramatic rate. In order to generate rapid speeds, a CPU must have more transistors, draw more power and have higher clock rates. This leads to a great deal of heat being produced by the CPU in the computer. If not been removed in time, the heat can accumulate and overheat the CPU, resulting in degradation of reliability and eventually in system malfunction.

Heat sinks have been added to all modern CPUs to alleviate the effect of the heat on the processor by enabling heat dissipation into the surrounding environment. A typical heat sink generally comprises a base contacting a CPU and a plurality of fins arranged on the base. Most of heat generated by the CPU is absorbed by the base, and is then conducted upwardly from the base to the fins. However, only a part of the base, usually the middle part, contacts the CPU. The heat originating from the CPU is directly absorbed by the middle part of the base and cannot be quickly spread to the other parts of the base. This results in an overheating of the middle part of the base, while the temperature of the other parts of the base is low. The fins on the other parts of the base away from the middle part are not efficiently used. It is therefore desirable to increase the efficiency of the heat sink by sufficient use of all of the fins on the base.

What is needed, therefore, is a heat dissipation device, which can overcome the above-described disadvantages.

SUMMARY OF THE INVENTION

A heat sink comprises a first plate having a top portion and a bottom portion, a second plate projecting from the top portion of the first plate, and a plurality of fins thermally contacting the second plate. The second plate has a width larger than that of the first plate. The heat pipe comprises a first portion embedded in the bottom portion of the first plate for directly contacting an electronic component to be cooled, and a second portion bent from one end of the first portion. The second portion is located at a side of the first plate. Heat generated by the electronic component is firstly received by the first portion of the heat pipe and then transferred to the side of the first plate of the heat sink via the second portion of the heat pipe, so that the heat can be evenly distributed over the first plate before it is dissipated to a surrounding environment through the fins.

DETAILED DESCRIPTION OF THE INVENTION

Referring toFIGS. 1-3, a heat sink100in accordance with a preferred embodiment of the present invention is illustrated. The heat sink100comprises a base110, a plurality of fins130vertically extending from the base110, and an S-shaped heat pipe150embedded in a bottom portion of the base110.

The base110is made of heat conductive material, such as aluminum, copper, and has a first plate112and a second plate114projecting upwardly from the first plate112for supporting the fins130. The first plate112is proximate to an electronic component, such as a central processing unit (CPU) to be cooled.

The first plate112has a width smaller than that of the second plate114, as a result, two steps (not labeled) are respectively formed at opposite sides of the first plate112. Three straight grooves1122are defined parallel and spaced apart in a bottom portion of the first plate112for accommodating the heat pipe150. Each of the grooves1122has a depth substantially the same as a height of the first plate112so that the second plate114is exposed to the grooves1122. One groove1122is located in a middle portion of the first plate112, and the other two grooves1122are positioned near respective opposite side ends of the first plate112.

The S-shaped heat pipe150comprises three parallel first portions152, and two second portions154interconnecting the neighboring first portions152. The second portions154are perpendicularly bent from opposite ends of a middle one of the first portions152along opposite directions, and extend between neighboring first portions152.

The first portions152of the heat pipe150are respectively retained in the grooves1122of the first plate112via riveting or pressing; as a result, the first portions152of the heat pipe150directly and tightly contact the first plate112and the second plate114without solder or other material. Thus, the heat resistance between the heat pipe150and the first plate112and the second plate114is reduced. Alternatively, the first portions152of the heat pipe150may be attached to the first plate112via welding or soldering.

After the first portions152of the heat pipe150are installed in the grooves1122of the first plate112, the second portions154of the heat pipe100are positioned at opposite sides of the first plate112, and parallel to sidewalls of the first plate112. Therefore, the second portions154of the heat pipe150are positioned in a space cooperatively defined by edges of the first plate112and edges of the second plate114, and the whole heat pipe150is positioned in a range defined by the edges of the second plate114. In this embodiment, the first portions152of the heat pipe100tightly abut against the first and second plates112,114, while the second portions154of the heat pipe150abut against the second plate114.

During operation, the heat sink100is positioned on a top surface of the CPU with one first portion152of the heat pipe100, particularly the middle one, aligned over the CPU. The middle first portion152of the heat pipe100serves to absorb heat originating from the CPU, and serves as an evaporator for the heat pipe100. The absorbed heat is then transferred to the rightmost and leftmost first portions152respectively via the second portions154along opposite directions. The heat of the rightmost and leftmost first portions152of the heat pipe150is conducted to the first and second plates112,114, and the rightmost and leftmost first portions152of the heat pipe150serve as two condensers for the heat pipe150. Finally, the heat accumulated at the base110is upwardly conducted to the fins130to be dissipated.

Thus, the heat originating from the CPU can be quickly absorbed by the first portion152, which is arranged at the central portion of the first plate112, and then be quickly spread to the other parts of the first plate112by the rightmost and leftmost first portions152of the heat pipe150. As a result, uniform temperature distribution over the whole first plate112is achieved. This serves to uniformly transfer the heat from the base110to the fins130and to improve the utilization of the fins130to dissipate the heat; thus, the efficiency of the heat sink100is promoted.

Moreover, each second portion154of the heat pipe150has one side abutting the second plate114and an opposite side exposed to ambient air. Therefore, the second portions154of the heat pipe150can transfer the heat to the second plate114and the ambient air, simultaneously. The provision of the two steps of the first plate112helps an airflow which can easily reach the first plate112, whereby the heat distributed over the first plate112can be more easily dissipated to the ambient air.

For facilitating mounting the heat sink100on the CPU, the heat sink100defines a channel160in a middle portion of the fins130for a clip being positioned therein.

FIG. 4shows a bottom plan view of a heat sink100ain accordance with another preferred embodiment. The heat sink100ahas a similar structure to the heat sink100as described above. The main difference is the arrangement of the heat pipes in the first plate112a. The heat sink100acomprises four straight grooves1122adefined on the first plate112aand two U-shaped heat pipes150a. Each heat pipe150ahas two parallel first portions152aembedded in the corresponding grooves1122aof the first plate112a, and a second portion154ainterconnecting the first portions152a. One of the first portions152aof each of the U-shaped heat pipes150ais located between the two first portions152aof the other U-shaped heat pipe150a. The second portions154aof the heat pipes150aare positioned at opposite sides of the first plate112a.

In this embodiment, the two heat pipes150aare so oriented that they open towards different directions, and each has one first portion152aextending into space defined by the other heat pipe150a. Moreover, the heat pipes150ahave two first portions152aclosely arranged in a center portion of the first plate112a, which is typically corresponds to a position for a CPU.